Abstracts from the 2014 Combined Scientific Meeting: Imaging and Radiation in Personalised Medicine. 4-7 September 2014, Melbourne Convention and Exhibition Centre, Melbourne, Australia. This supplement is a joint publication with the Journal of Medical Imaging & Radiation Oncology: Vol. 58, Suppl. 1, September 2014, Pages 1-352.

Journal of Medical Imaging and Radiation Oncology (2014) 58, 1–62 Journal of Medical Radiation Sciences (2014) 61, 1–62

Combined Scientific Meeting Imaging and Radiation in Personalised Medicine 4–7 September 2014 Melbourne Convention and Exhibition Centre

Thursday 4 September, 0820–1000 Combined Opening Plenary: Radiation and Personalised Medicine Too much of a good thing: The uncritical use of medical imaging B Hillman Departments of Radiology and Medical Imaging and Public Health Sciences, University of Virginia, Charlottesville, Virginia, United States of America

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Predicting radiation related morbidity J Overgaard Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark Practically all curative intended radiotherapy is limited in dose and indication by the risk of treatment related morbidity. We therefore need to have a clear understanding of the nature and risk of morbidity, including whether such risk is individual and may differ from patient to patient. Although there are increasing evidence for the latter has radiogenomic based strategies not yet been implemented in clinical practice. More successful have we been with technical approaches allowing dose sparing treatments. Thus, the newer technological developments in radiotherapy by IMRT and particle beam irradiation are strongly based on an argumentation of securing reduced morbidity. Not that the evidence for that exist to a large extend, but due to simple intuition (and then later hopefully some clinical data in support). We are therefore both guided and haunted by a diffuse risk of morbidity, without really knowing if we can predict a biological variation between individual patients. The presentation will be a reflection on some of these issues related to this situation, mainly by outlining the problems, rather than to point to a solution.

It is incontestable that the medical imaging innovations of the past forty years have made health care safer and more effective. However, the success imaging has enjoyed has made for an anti-imaging bias among payers and regulators who consider any growth in imaging to be wasteful. In fact, some growth in the use of imaging is not only appropriate but desirable. In most developed countries, the average age of the population is increasing. Given how effectively medical imaging is employed in diagnosing chronic conditions and monitoring changes with treatment, growth related to aging is appropriate and to be expected. If this were all there were to it, there would be no problem, however, a significant fraction of imaging use is inappropriate, related to aberrant incentives and uncritical patterns of use. The former includes abuse related to third party payment for care, self-referral by non-radiologist physicians, ‘churning’ on the part of radiologists, and defensive medicine practiced for fear of legal action. Perhaps most significant of all, however, is the failure to think critically about the likelihood of disease being present, the performance characteristics of the test, and the risks of testing before performing an imaging examination. The source of this behavior is traceable to how physicians are educated and trained. Medical students and registrars are largely educated and trained in academic medical centers, where faculty physicians are expected not only to provide clinical care but to conduct research, teach, and be responsible for administrative functions. The emphasis is on efficiency, and the students and registrars soon learn that doing something – even if the odds are low that imaging will benefit the patient – is preferable to watchful waiting. Upon leaving academe, the newly minted physicians often take this ‘shotgun’ approach to practices that have lower rates of disease and acuity index, making uncritical use even more wasteful. To reduce unnecessary and inappropriate imaging, radiologists must reassume their consultative role, teach rigorous critical reading and thinking, and act solely in the best interest of their patients.

Journal of Medical Imaging and Radiation Oncology and Journal of Medical Radiation Sciences © 2014 Combined Scientific Meeting

2 First do NO harm – A framework for safe care in radiology P Cavanagh

Oral Abstracts

Thursday 4 September, 1030–1230 Concurrent Session: New Technologies (collaborative)

Musgrove Park Hospital, Taunton, Somerset, United Kingdom

MR guided hippocampal sparing whole brain radiotherapy

Aim: The aim of this presentation is to consider what are the key primary drivers that, if addressed effectively, will deliver a safer environment for patients and the healthcare professionals who provide the services. Despite the best endeavors of individuals who set out to help and not harm the patients they look after, there are every day reminders of the fact that all humans make errors and some of these run the risk of devastating results. Safety is a systems property and there for any system must have in place well understood process that pro-actively seek out potential risk and put in place actions that will protect from such error and where this is not possible mitigate against the potential harm it may result in. The presenter with an appointed patient safety advisor has developed a framework that imaging departments could use as an aid to improve their safety systems. The four key drivers this model highlights are: • Leadership and teamwork • Safety monitoring and learning systems • Patient focused and responsive care • Professional and organizational resilience The presentation will give an overview of how these noble aims can be turned into meaningful actions.

WA Tomé Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York, United States of America Aim: It has been hypothesized that cognitive decline following whole brain radiation therapy might be mitigated using intensity-modulated hippocampal avoidance WBRT (HA-WBRT). We present various planning techniques that allow one to successfully achieve the dosimetric objectives set forth in RTOG 0933 and arrive at acceptable plans that meet all protocol constraints. Methods: 5 anonymized patient data sets containing gold standard hippocampus contours that where generated using the RTOG 0933 contouring atlas where planned to receive HA-WBRT to 30 Gy in 10 fractions. The dose is prescribed to cover 90% of the whole brain planning target volume (PTV) by the prescription dose, while keeping maximum dose to 2% of the PTV (D2%) to 37.5 Gy, and the minimum dose to 98% of the PTV (D98%) to no less than 25 Gy. The planning objectives for the hippocampus are such that 100% of the hippocampus should not receive more than 9 Gy, and the maximum dose of the hippocampus should be kept to less than 16 Gy. In addition, the maximum dose to optic nerves and chiasm should be constrained to less than 37.5 Gy. For each of the 5 patients a conventional 9 field IMRT plan using two protocols recommend field arrangements, a coplanar and non-coplanar VMAT plan, a VMAT plan using a PTV subvolume technique, and a Rapid Arc plan using the PTV subvolume technique combined with a Arc subdivision technique, as well as a Tomotherapy plan using protocol recommended planning parameters was generated. Results: Using various planning techniques detailed above all dosimetric constraints could be met for each delivery technique. However, to further improve VMAT plans it was found that a PTV subvolume technique did yield improved results, while for Rapid Arc it was found that in addition to the PTV subvolume technique a subdivision of the Arcs into a superior and inferior arc overlapping on the PTV subvolume containing the Hippocampus was necessary in order to meet protocol constraints. Conclusion: We have shown that independent of delivery technique treatment plans that meet all protocol constraints can be consistently generated.


Oral Abstracts

3

An overview of the role of MRI in radiotherapy

Australia’s first CyberKnife: Preliminary experience

treatment planning, delivery and treatment

R Kearvell, P Podias, S Condron, J Lane, G Grogan,

response – Current status and future directions

S Bydder, C Tang, D Waterhouse, C Harper, B Yap,

G Delaney

M Ebert and M Kedda

Liverpool Cancer Therapy Centre, Sydney, Australia

Sir Charles Gairdner Hospital, Western Australia, Australia

Aim: To provide an overview of the current status and future directions of the use of MRI in the radiotherapeutic management of cancer. This will include discussing the basics of MRI terminology and the various different sequences, providing an overview of the use of MRI in the diagnosis of malignancy, current use in planning and the possible future direction of MRI simulation, with reference to the current literature. Method: A literature review was performed to assess the current role of MRI in radiotherapy1. A description of that overview will be provided. Results: MRI has an increasing role to play in radiation oncology management, including improved delineation of tumours and organs at risk2, the exclusion of sensitive structures, and possibly in the use of functional imaging and perhaps real-time targeted radiotherapy using an MRI-linac3. The current status of the Australian MRI linac program will be described as well as the other international efforts to use MRI in real-time targeting. Conclusion: MRI has a very important and increasing role in the radiotherapeutic planning, treatment delivery and response assessment of cancer care. MRI holds significant future potential as clinical expertise and the research-base expands in the radiation oncology community.

Aim: The CyberKnife combines a manufacturing robot with a linac and imaging system to enable the user to track the target, detect a mismatch and correct the position of the linac repeatedly throughout treatment. Australia’s first CyberKnife was installed at Sir Charles Gairdner Hospital in January 2014 with the first patient treated in early April. This report will describe the preliminary experiences using the CyberKnife to treat a variety of tumour sites. Method: Installment to first treatment was 12 weeks. In that period, workflow from consult to treatment was defined, as was patient information, policy and procedural documentation. Commissioning was also completed and the modulator cupboard redesigned. Staff had 2 weeks training in the US and onsite training was provided the week before “go live.” Patients are triaged for CyberKnife treatment according to tumour site, size, and pathology and performance status. The dose and fractionation are biologically equivalent to established external beam prescriptions. Information such as demographic, treatment plan and toxicity for each patient is recorded and reported in the RSSearch database maintained by the International Stereotactic Radiosurgery Society. Results: A number of patients with brain, prostate, lung, and liver lesions have been treated using the CyberKnife since April 2014. This has allowed the full capabilities of the CyberKnife to be utilised and helped staff to become familiar with the range of treatments, which the device is capable of delivering. Conclusion: This unique piece of radiation therapy equipment has required a steep learning curve to ensure its successful implementation into the clinical setting. A conscientious assessment of the technology will require both the monitoring of short to intermediate-term patient outcomes as well as assessment of the impact of the technology on workflow processes. The ultimate outcome will be quantification of the cost-effectiveness of radiotherapy delivery with the device.

References 1. Metcalfe P, Liney GP, Holloway L, Walker A, Barton M, Delaney GP, Vinod S, Tome W. The potential role for MRI in radiation therapy treatment planning. Technology in Cancer Research and Treatment 2013; 12(5): 429–46. 2. Liney GP, Moerland MA. Magnetic resonance imaging acquisition techniques for radiotherapy planning. Sem Rad Onc 2014 (in press). 3. Keall PJ, Barton M, Crozier S. The Australian MRI-Linac Program. Sem Rad Onc 2014 (in press).


4

Oral Abstracts

Ultrasound transit time spectroscopy for improved tissue

First clinical implementation of Calypso-guided MLC

characterisation and imaging

tracking

C M Langton and M-L Wille

J Booth,1,2 E Colvill,1,3 P Keall,3 F Alfieri,1 L Bell,1

Queensland University of Technology, Brisbane, Australia

H Vaithianathan,1 A Kneebone1 and T Eade1 1

Aim: To test the hypotheses that Ultrasound Transit Time Spectroscopy may a) reliably estimate the solid volume fraction (SVF) of cancellous bone replica models, and b) improve image fidelity (IF) by identifying signal locations that have otherwise been lost in noise. Method: We recently proposed that ultrasound wave propagation in complex media such as cancellous bone may be described by a concept of parallel sonic rays, the transit time of each ray defined by the proportion of bone and marrow propagated [1]. Through deconvolution of the transmitted and received ultrasound signals, a Transit Time Spectrum (TTS) plots the proportion of sonic rays having a particular transit time [2]. SVF: Ultrasound signals were recorded in ten simplistic acrylic: water step-wedge cylindrical models; a range of transit time lateral inhomogeneities achieved by varying the thickness of solid component. IF: Two coaxially-aligned ultrasound transducers (transmitter and receiver) were positioned in a water bath, the water-air interface acting as a reflector; the received ultrasound signal consisted of the ultrasound wave from the direct path between the two transducers and a secondary ultrasound wave reflected from the water-air interface. The ability of deconvolution to identify the two separate transit time paths was compared with the standard technique of matched-filtering. Results: SVF: Agreement (R2) between true (geometric calculation) with both predicted (computer simulation) and experimentally-derived values were 99.9% and 97.3% respectively. IF: Although the two peaks were indeterminable in the raw data, both the matched-filtering and the deconvolution approaches provided transit time spectra with two distinct peaks at the expected values. While matched-filtering has a better accuracy (0.13 μs vs. 0.18 μs standard deviation), deconvolution has a 3.5 times improved side-lobe to main-lobe ratio. Conclusion: Ultrasound Transit Time Spectroscopy offers a new analytical tool with the potential to provide improved sample characterisation and image fidelity.

Northern Sydney Cancer Centre, Royal North Shore

Hospital, 2School of Physics, University of Sydney, 3School of Medicine, University of Sydney, New South Wales, Australia Aim: MLC tracking presents a paradigm shift in radiotherapy, allowing the widespread application of real-time adaptation during treatment delivery and promising a new level of dose conformity. The first prostate cancer patients have been treated with Calypso-guided MLC tracking, as part of a 30-patient clinical trial to demonstrate feasibility (NCT02033343). The purpose of this work is to present the development of novel clinical processes to ensure safe delivery of this pioneering technique and lessons learned from initial patients. Method: The MLC tracking system consists of an electromagnetic transponder tracking signal and in-house MLC tracking software combined with VMAT delivery. Planned analysis includes fractions successfully adapted, geometric accuracy and dosimetric accuracy of delivered versus planned dose accumulation. Failure Mode and Effects Analysis (FMEA) was applied to evaluate the safety of the MLC tracking system prior to the first treatment. Patient-specific quality assurance tests and novel clinical processes were developed by process mapping and FMEA to ensure safe patient treatment delivery. Results: Application of FMEA QA framework produced measurement of system latency as 230 ± 20 ms; coordinate system and scaling were correct; all anomalous situations were detected and initiated a beam hold. We implemented checklists to ensure the additional processes were completed. To date, six patients have been treated, all fractions have successfully adapted and DVH’s show the tracking delivery is more reproducible than untracked. The average treatment time for the dual-arc VMAT delivery was 114 ± 2 s. With MLC tracking, there is no need for a pre-treatment couch shift or intra-treatment couch corrections of observed motion, thus improving patient flow further.

References Langton C M & Wille M-L; 2013; Experimental and computer simulation validation of ultrasound phase interference created by lateral inhomogeneity of transit time in replica bone:marrow composite models; Engineering in Medicine; 227(8), 890–895. Langton C M, Wille M-L, Flegg M B; 2014; A deconvolution method for deriving the transit time spectrum for ultrasound propagation through cancellous bone replica models; Proc IMechE Part H: J Engineering in Medicine; 228(4) 321–329.


Oral Abstracts Biodosimetry for synchrotron microbeam radiation therapy at the European Synchrotron Radiation Facility

5

Thursday 4 September, 1030–1230 Concurrent Session: Neuroradiology

J Crosbie,1 O Nuta,2 C Nowell3 and P Rogers1 1

University of Melbourne, Dept of Obstetrics & Gynaecology,

Imaging of the spondyloarthropathies: What the

Melbourne, Australia, 2King Faisal Specialist Hospital &

rheumatologist wants. What the radiologist needs

Research Centre Riyadh, Saudi Arabia, 3Faculty of

to know

Pharmacy, Monash University, Parkville, Victoria, Australia

M Leech1,2 and P Naidoo1,2,3 1

Aim: The aim of this study is to biologically assess the dose delivered to the ‘valley’ regions between microbeam peaks for different cell lines. We propose a bio-dosimetry method based on the γ-H2AX immunohistochemical marker to measure radiation-induced DNA double strand breaks in cells and skin tissue, from microbeam and broad beam exposures. Method: We sub-cultured two types of mouse cell lines: 4T1.2 mouse mammary tumour cells and L929 mouse mammary fibroblasts. We irradiated chamber slides containing the cells on the ID17 bio-medical beamline with the following in-beam MRT doses: 20, 50, 100, 150 Gy. These MRT doses were selected to ensure the valley dose remained below 5 Gy. We also irradiated the cells with known doses (0.5, 1.0, 2.0, 3.5 Gy) of conventional X-rays with a similar energy spectrum as the MRT beam, in order to provide us with a calibration curve. The slides were formalin-fixed approximately 45 mins post-irradiation and stained with the phosphorylated-H2AX antibody. Results: We photographed the irradiated regions using highresolution (×63 oil immersion objective lens) fluorescence microscopy. The cells irradiated with low dose BB radiation showed a classic dose response; increasing foci observed with increasing dose. The γ-H2AX signals were saturated in the microbeam peak regions whereas low level foci were observed in the valley region, thus allowing us to quantify the valley dose. Conclusion: There is currently no single dosimeter with the dynamic range and spatial resolution to adequately measure the twodimensional MRT dose distribution. An accurate, measurement-based system of dosimetry will undoubtedly contribute to the MRT knowledge base and importantly is essential if MRT is ever to be clinically accepted. The bio-dosimetry method has very high spatial resolution (foci dimensions are sub-micron) and provides accurate measures of biological dose distribution from an MRT beam.

Monash University, Melbourne, Australia, 2Monash Health,

Melbourne, Australia, 3Imaging Independently, Melbourne, Australia To discuss the key clinical features of the spondyloarthropathies, with particular emphasis on areas that relate to accurate diagnosis and staging of these diseases in a time of increasingly complex disease classification and more sophisticated targeted therapies. The perspectives of an experienced Rheumatologist, and Radiologist both of whom participate in a large MDT, will be shared with the audience in this session. Real cases will be used to illustrate important clinical features pertaining to this group of diseases, in conjunction with imaging approaches, key findings, and pitfalls.


6

Oral Abstracts

Pars stress fractures overview. Assessment of 3T MRI

Stump the stars or read with the expert

with 3D T1 VIBE sequence as the primary investigation

S Stuckey and S Khangure

for pars stress fractures compared to CT AH Rotstein,1 F Malara,1 T O’Shea,1 J Roebert,1

Abstract not available at time of publication.

M Schneider-Kolsky,2 A Kountouris3 and A Robertson1 1

Victoria House Medical Imaging, Melbourne, Australia,

2

Monash University, Melbourne, Australia, 3Cricket Australia,

Melbourne, Australia Aim: Assess the performance of 3T MRI with T1 3D VIBE sequence in the detection and grading of pars stress fractures compared to CT. Method: Retrospective audit of 70 pars interarticularis at 35 vertebral levels in 24 patients by 4 clinically blinded radiologists. The MRIs and CTs were reviewed separately. On CT, each pars was assessed for fracture and sclerosis. On MRI, each pars was assessed for fracture, sclerosis and bone marrow oedema. Fractures were graded into incomplete and complete on both MRI and CT. For each imaging finding, the statistical performance of each radiologist and the radiologists as a consensus group was derived. The performance of MRI compared to CT was reviewed. Results: Excellent agreement between individual radiologists and the consensus radiologists’ opinion for MRI compared to CT for pars fractures and sclerosis. Specific results will be presented in the lecture. Conclusion: 3T MRI with T1 3D VIBE sequence has excellent performance as the initial investigation for pars stress fractures when compared to CT.


Oral Abstracts My (practical) approach to white matter disease C O’Donnell Abstract not available at time of publication.

7

Thursday 4 September, 1030–1230 Concurrent Session: Quality and Safety Cross-sectional post-mortem imaging 2014 W Bailey1,2,3,4,5,6 1

University of Salford, Manchester, 2University of Bangor,

Wales, 3Manchester Royal Infirmary, Manchester, 4

Bridgewater Hospital, Manchester, 5College of

Radiographers, UK, 6Society of Radiographers London, UK Cross-sectional post-mortem imaging has been used to varying levels over the last 20 years. In a world where people’s perceptions are changing, post-mortem is not the ideal choice on both moral and cultural reasons. I relay my experiences in participation in the U.K.’s largest study, look at what the study showed, evaluate the results and discuss potential new developments and innovations in the future.


8

Oral Abstracts

Investigating errors in medical imaging: Lessons for

In vivo dosimetry program at the William Buckland

practice from closed cases in the Radiology Events

Radiotherapy Centre, The Alfred

Register (RaER)

L Smith

T Schultz,1 S Goergen,2 A Deakin1 and B Runciman1

Alfred Health, Melbourne, Victoria, Australia

1

Australian Patient Safety Foundation, Adelaide, South

Australia, Australia, 2Monash Health, Victoria, Australia Aim: Medico-legal cases are a particularly helpful data source for providing information on rare and serious adverse events in healthcare. Although some medical disciplines (notably anaesthesia) have proactively analysed these data, others, including radiology, have yet to fully exploit these data to improve patient safety. The aim of this study was to analyse the modality and error types contained in a radiology medico-legal dataset in the Radiology Events Register (RaER) to better understand these data and inform practice and standards development in radiology. Method: We analysed a total of 443 medico-legal (closed case) incidents provided to the Radiology Events Register (RaER) against two criteria: (i) 12 relevant patient safety fields and (ii) the imaging modality for comparison against Medicare data collected over the corresponding time period (1994–2007). Results: Analysis was restricted to 401 complete incident reports. The analysis indicated that the level of detail contained in the claims was only fair, with a mean of 5.8 ± 1.8 (SD) patient safety fields (range 2–10) discernible. Modality was apparent in 315 incidents (79%); the mean number of modalities per incident was 0.88 ± 0.55 (range 0–3). Radiography accounted for just over half of modalities measured, ultrasound for 26%, CT for 16%, MRI for 4% and nuclear medicine for 2%. We encountered difficulties in obtaining further granular detail about sub-modality suitable for cross-matching against the Medicare data. Conclusion: We conclude that despite some limitations, medico-legal data deserve further attention of patient safety analysts.

Aim: To describe a project to establish and implement an in vivo dosimetry program for all patients commencing megavoltage external beam treatment at WBRC to improve quality and safety for patients and to assess the feasibility of Allied Health Assistants (AHAs) supporting radiation oncology medical physics (ROMPs) and radiation therapy (RT) staff in delivering the program. Method: Funding was obtained from Department of Health Victoria to support the development and implementation of a 1-year project. Two Allied Health Assistants with AHA Certificate 3 and 4 were recruited and trained by a medical physicist and radiation therapists over a 3-month period in in vivo dosimetry equipment, procedures and patient care as it relates to radiation therapy. Treatment bunkers were cabled up to provide for streamlined measurement processes and new software was written to facilitate data collection and analysis. Action levels were established to define when repeat measurements are required and normal corrective action applies if discrepancies between predicted and measured doses occur. Results: The first in vivo measurements were successfully performed with support from ROMPs and RT staff in early May 2014. The AHAs have proven competent and sufficiently skilled to effectively and efficiently assist in the programme and are expected to operate with little or no supervision in the near future. Conclusion: The program has to date demonstrated the important role AHAs are able to play in delivering an in vivo dosimetry program at The Alfred. It is envisaged that the in vivo program will be ongoing and other assisting roles for the AHAs may be investigated in the future.


Oral Abstracts

9

The ACDS pilot: Summary of outcomes from the bespoke

A Steward,1 S Broeren,1 M Schneider-Kolsky2 and L Bentley1

design 1

1

I Williams, J Lye, J Lehmann, 1

1

5

1,2

J Kenny,

1,3

1,4

1

6

Victoria, Australia

L Dunn,

5

A Alves, A Cole, P Johnston, D Butler and T Kron 1

A snapshot of a week in radiology Western Health, Melbourne, Australia, 2Monash University,

Australian Clinical Dosimetry Service, Melbourne, Victoria,

Australia, 2University of Sydney, Sydney, Australia, 3

Radiation Oncology Queensland, Queensland, Australia,

4

Olivia Newton-John Cancer and Wellness Centre,

Melbourne, Victoria, Australia, 5Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Victoria, Australia, 6Peter MacCallum Cancer Centre, Brisbane, Australia Aim: The Australian Clinical Dosimetry Service (ACDS) is a pilot programme to enable the Australian Government to determine whether this design of an audit programme was suitable. The outcomes from the 3 years of operations will be presented and discussed with a focus on the whether the pilot requirements were met and why. Method: Designed over 2010/11 by experts drawn from the three professions in consultation with the national Department of Health, a list of outcomes required over a 3-year time frame was formulated. These outcomes were central to a Memorandum of Understanding, (MoU) between Health and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), which hosted the ACDS. The MoU defined the operational and reporting requirements for the ACDS and the need for external advisors drawn from the hospitals: the Clinical Advisory Group (CAG). Results: The ACDS has achieved all the MoU requirements. This paper describes how the staff within the ACDS engaged with the professional clinical workforce and provided a successful and functioning audit service. It identifies the strengths and weaknesses within the MoU and the ACDS structure and how the ACDS resolved a number of conflicting issues. It identifies the successes within the ACDS and how these were achieved. It provides details to assist and advise those seeking to design or modify national or regional auditing programmes. Finally, the paper reviews the potential future for the ACDS. Conclusion: The raw number of audits and outcomes indicate that the ACDS has met the MoU auditing requirements. The reasons for the ACDS’ success are highly dependent on: attracting quality staff who can respond with agility to changing situations, a high level of communication with the professional community, and a high level of engagement by the community.

Introduction: Radiology plays a vital role within the modern healthcare system; it involves communication between medical imaging staff, referrers and other hospital staff. There are worldwide studies that suggest communication problems in hospitals, between radiology and other departments, particularly with the ability to transfer and exchange important patient information. This leads to the question of ‘Are radiology request forms being adequately filled out with all necessary information?’ and ‘Are radiologists providing useful information back to referrers?’ With this research project, we hope to identify common inadequacies in communication with regard to the completeness of the request form while also identifying any deficiencies in the subsequent radiology reports. We have retrospectively reviewed all request forms and radiology reports in a period of 1 week at a three campus major hospital in Melbourne. Our goal is to provide a snapshot of radiology in Australia. We hope this research will provide useful data that can be beneficial to future research and to promote the importance of communication between medical professionals. Methods: This study was a retrospective analysis of all request forms and radiology reports tendered to our department over a 1-week period. The extensive data collected were analysed with SPSS version 21 statistical software. Results: More than 1,700 request forms and subsequent radiology reports were reviewed. A clinical question was not provided in more than 17% of cases with other information deemed relevant omitted in more than 30% of cases. Conclusion: This study has shown that there exist significant inadequacies in the completion of radiology request forms and thus, communication between radiology and referrers within Australian hospitals is substandard. There is a need to improve on the effectiveness of communication between referrer and radiology in order to utilise radiology to its full potential in the diagnosis and management of patients.


10 Development of a dynamic scheduling tool to reduce waiting room times at Liverpool and Macarthur Cancer Therapy Centres?

Oral Abstracts

Thursday 4 September, 1030–1230 Proffered Papers: Radiation Therapy and Oncology: Breast

D Moretti Liverpool Cancer Therapy Centre, New South Wales,

Predictive value of immunohistochemical 4+clinical

Australia

treatment score in determining risk of locoregional recurrence in early breast cancer

Aim: The aim of this project was to test if the development of a dynamic scheduling tool would reduce the patient waiting room times at Liverpool and Macarthur Cancer Therapy Centres (LMCTC). Method: This project retrospectively analysed patients treated at LMCTC from the 1 October 2010 to 31 December 2012. Using Mosaiq 2.30, Crystal reports 11 and Microsoft Excel 2007, the project monitored waiting room times before and after the implementation of a new scheduled duration (SD) tool, built specifically to analyse SD and to aid in dynamic scheduling. The report was run weekly and the staff were asked to monitor each patient’s appointments and adjust the duration. The data were analysed to test the new SD tool against the previous BTE model such as Delaney et al., 2005 and to determine if any other factors influenced the SD, such as patient factors or changes in radiotherapy trends and technology. Results: The implementation of this SD tool has aided LMCTC in a reduction of the overall waiting room time by 2 minutes per patient. The proportion of patients treated within 10 minutes of their scheduled appointment time has increased from 54% to 68%. The patient factors that were found to have a significant influence over the SD were inpatient status (increase of 2.7 minutes) and patient age (range of +/−1.5 minutes). Changes in radiotherapy trends and technology such as treatment delivery and CBCT also had some impact. Conclusion: The results have indicated that LMCTC has benefited from developing a dynamic scheduling tool. If this tool was applied to other cancer therapy departments, it could aid them in reducing patient waiting room times, reducing stress levels for staff and improving efficiency. Reference Delaney GP, Shafiq RJ, Jalaludin BB. The development of a new basic treatment equivalent model to assess linear accelerator throughput. Clinical Oncology 2005; 17: 311–8.

R Lakhanpal,1 T Phillips,2 B Shadbolt,3 G Bennett,4 M Brown5 and A Rezo6 1

Department of Radiation Oncology, The Canberra Hospital,

2

Department of Pathology, The Canberra Hospital,

3

Statistician, The Canberra Hospital, 4Department of

Pathology, The Canberra Hospital, 5Department of Pathology, The Canberra Hospital, 6Department of Radiation Oncology, The Canberra Hospital, Australian Capital Territory, Australia Aim: Genomic tools to predict risk of locoregional recurrence (LRR) in breast cancer are evolving. Immunohistochemical 4 (IHC 4) +Clinical Treatment Score (CTS) is an inexpensive alternative to Oncotype Dx, which predicts for distant recurrence.1 Given LRR is a significant predictor for risk of distant recurrence, our hypothesis is that this score also predicts for LRR. Method: This is a prospective cohort study on women with early breast cancer who did not receive adjuvant radiation post-breast conserving surgery (BCS) (study group) identified from the local database from July 1997 to June 2010. The scores were calculated using the appropriate formulae and patients were categorised into low, intermediate and high risk using the cut offs used in the study by Cuzick et al.1 The secondary endpoint was to determine the differences between this study group and women with early breast cancer who had adjuvant radiation post BCS (control group). Results: Using cox regression, there was a statistically significant association between this score as a continuous variable and LRR. Inflection point analysis found critical inflection points similar to the cut offs derived from the original study on distal recurrence.1 Applying these cut offs to LRR produced a significant difference between the low risk and the high risk group (p = 0.03). The relative risk of LRR between the intermediate risk and high risk group was not significant (p = 0.9). These results suggest this score has most of its utility in predicting patient with low risk of LRR. Study group included predominantly elderly, postmenopausal, rural patients with low grade, node negative tumours compared to the control group. Conclusion: This is the first study to demonstrate a statistically significant association between the IHC4+CTS and risk of LRR in women with early breast cancer, which can be used to identify women at low risk of LRR. Reference 1. Cuzick J, Dowsett M, Pineda S et al. Prognostic value of a combined estrogen receptor, progesterone receptor, Ki-67, and human epidermal growth factor receptor 2 immunohistochemical score and comparison with the Genomic Health recurrence score in early breast cancer. Journal of Clinical Oncology 2011 November 10; 29 (32): 4273–8.


Oral Abstracts

11

The influence of pretreatment 18F-FDG PET/CT in

Setup error in tangential breast radiotherapy:

radiation therapy management for patients with locally

Comparison of electronic portal image and cone-beam

advanced breast cancer: A prospective comparison with

computed tomography

conventional imaging

V Batumalai,1,2 P Phan,1 C Choong,1 L Holloway1,2,3,4

1

1

2

S Ng, S David, M Alamgeer and V Ganju

2

and G Delaney1,2

1

Peter MacCallum Cancer Centre, Melbourne, Australia,

1

2

Monash Cancer Centre, Melbourne, Australia

NSW, New South Wales, Australia, 2University of New South

Liverpool Cancer Therapy Centre and Ingham Institute,

Wales, New South Wales, Australia, 3Centre for Medical Aim: To evaluate the diagnostic performance of pretreatment 18Ffluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and its impact on radiation therapy treatment decisions in patients with locally advanced breast cancer. Method: Patients with locally advanced breast cancer with good performance status and no contraindication to neo-adjuvant chemotherapy, surgery and adjuvant radiation therapy were enrolled on a prospective trial. All patients had pretreatment conventional imaging (CI) performed including bilateral breast mammography and ultrasound, bone scan, and CT chest, abdomen and pelvis performed. Informed consent was obtained prior to enrolment. Pretreatment whole body 18F-FDG PET/CT scans were performed on all patients and results were compared to CI findings. Results: One hundred forty-six patients with locally advanced breast cancer with no clinical or radiological evidence of distant metastases on CI were enrolled. Median age was 49 (range:26–70). PET/CT detected distant metastatic disease and/or locoregional disease not visualised on CI in 31 (21.2%) patients. Distant metastatic disease was detected in 17 (11.6%) patients – 6 (4.1%) had bony metastases, 5 (3.4%) had intrathoracic metastases (pulmonary/ mediastinal), 2 (1.4%) had distant nodal metastases, 2 (1.4%) had liver metastases, 1 (0.7%) had pulmonary and bony metastases, and 1 (0.7%) had mediastinal and distant nodal metastases. Of the remaining 129 patients, nodal disease outside conventional radiation therapy fields was detected on PET/CT in 14 (10.9%) patients, with involvement of ipsilateral internal mammary nodes in 12 and ipsilateral level 5 cervical nodes in 2. One patient had an FDG-avid liver lesion detected, which was subsequently classified as non-metastatic on triple phase CT abdomen. Conclusion: PET/CT scan provides superior diagnostic and staging information in patients with locally advanced breast cancer compared to CI, which has significant therapeutic implications with respect to radiation therapy management. Consideration will be given when designing radiation therapy fields to include the involved locoregional nodal sites.

Radiation Physics, University of Wollongong, New South Wales, Australia, 4Institute of Medical Physics, University of Sydney, New South Wales, Australia Aim: Electronic portal imaging (EPI) is gradually being replaced by cone-beam computed tomography (CBCT) for target localisation with a major advantage of three-dimensional (3D) visualisation of the patient’s anatomy, especially for internal organs. However, the utility of CBCT over EPI in breast radiotherapy has not been thoroughly evaluated and involves additional financial costs and radiation exposure to the patient, with these patients having high rates of long-term survival. The aim of this study was to quantify the differences in setup errors detected with the CBCT and EPI for breast radiotherapy. Method: Twenty-five patients undergoing tangential breast radiotherapy were randomly selected to participate in the study as per the sample size calculation. All patients had a routine planning computed tomography (CT) scan in the supine position. Large patients were excluded due to setup and machine limitations. CBCT scans were acquired prior to fractions 2, 7, 12, 17 and 22. The CBCT scans were rigidly registered to the planning CT using bony anatomy. Digitally reconstructed radiographs (DRR) were generated from CBCT to simulate EPI using treatment planning system (Focal, Xio v4.64). The simulated EPI images were compared to the planning DRR using bony anatomy in the superior-inferior (SI) and anterior-posterior (AP) directions. Systematic error (Σ) and random error (σ) were measured for EPI and CBCT. A paired Student’s t-test was used to compare results. Results: The setup errors between EPI and CBCT were comparable (Table 1). The largest discrepancy between the two imaging modalities was 1.1 mm for random error in the AP direction. The differences were not statistically significant. Table 1. Comparison of setup errors between EPI and CBCT EPI

Σ (mm) σ (mm)

CBCT

SI

AP

SI

AP

4.4 6.2

3.7 4.9

4.3 6.8

3.3 6.0

Conclusion: The overall setup errors measured for CBCT and EPI were comparable. CBCT was not superior to EPI in measuring setup error in breast radiotherapy. Unless other studies show different results, we recommend against routine CBCT for patient setup in tangential breast radiotherapy.


12

Oral Abstracts

Deep inspiration breath hold for left-sided breast Ca:

Gene expression signature for late radiation effects in

Our experience

breast cancer

G Osbourne, S David and D Phillips

M McKay,1 H Forrester,2 J Li,3 T Leong4 and C Sprung2

Peter MacCallum Cancer Centre, Victoria, Australia

1

Sydney University and North Coast Cancer Institute,

Sydney, Australia, 2Centre for Innate Immunity and Aim: To describe the implementation of deep inspiration breath hold clinically into our department, the issues encountered and the current practice, including patient selection and the impact on the department. Method: Left-sided breast cancer patients are selected for deep inspiration breath hold technique (DIBH) based on the planning CT scan acquired in treatment position. The determining factors for DIBH include heart position and mean cardiac dose (MCD), and breast tissue dose coverage, in combination with other clinical considerations. Patients selected to have DIBH will have a 4DCT using bellows to assess breathing motion, with patient breathing training occurring before the DIBH CT scan. Treatment planning was completed on the DIBH scan and MCD was assessed – if there is a benefit derived from the DIBH scan, treatment was given employing DIBH. Treatment utilises the Varian RPM system on the Linear Accelerator to assess the patient breathing pattern. Daily imaging was used to assess reproducibility. Results: Twenty-six patients have completed treatment using DIBH. Preliminary analysis of the data indicates that the MCD for the plans with free breathing was 4.4 Gy (+/−1.3) and when using DIBH, the MCD reduced to 2.2 Gy (+/−0.7). While minimum dose coverage to breast tissue for the free breathing plans was 93.8% (+/−12.6) and the DIBH plans 99.5% (+/−1.2) Conclusion: DIBH demonstrates a significant reduction in MCD for left-sided breast cancer patients, while maintaining breast tissue coverage. The early identification of patients that require DIBH by utilising previous diagnostic imaging will eliminate the need for the free breathing planning CT scans. Furthermore, other clinical areas would particularly benefit from using this technique, especially any radical breast/mediastinal treatment where MCD is an ongoing survival issue.

Infectious Disease, Monash Institute of Medical Research, Monash University, and MIMR-PHI Institute of Medical Research, Clayton, Victoria, Australia, 3Division of Division of Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia, 4Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia Aim: Individuals with heightened normal tissue sensitivity restrict the doses at which therapeutic radiation can be delivered for the treatment of breast and other cancers. Likely sensitive individuals cannot currently be detected prior to radiotherapy, with the exception of those with some rare recessive genetic disorders, such as ataxiatelangiectasia compound heterozygotes. Genetic variation is a likely source for normal tissue radiosensitivity and hence understanding the involved genetic factors has been an intense focus of radiation research for many years. Recent advances in biotechnology have enabled interrogation of biological samples with unprecedented precision and scope. Method: We used the approach of exon expression microarrays to compare the genome-wide basal gene expression profiles of primary fibroblast cell lines derived from six late fibrosis breast cancer sufferers and six matched controls without fibrosis. These data were confirmed with quantitative reverse transcriptase-PCR and RNA-seq, the latter being another genome-wide technique. Results: We identified an 8-gene expression signature of the late radiosensitive phenotype. The signature genes comprised FBN2, FST, NOTCH3, PLCB1, DDIT4L, DPT, GPRC5B and SGCG. Analysis after removal of any of the included genes increased p-values and two of the genes, FST and GPRC5B, could in isolation also predict radiosensitivity. Both the exon array and RNA-seq data showed that the 8-gene expression prediction capacity was recapitulated when the same cells were irradiated (ionising radiation; 10 Gy, 4 hr), supporting the validity of the basal results. Most of the signature genes are related to fibrosis, by virtue of their regulation by TGFβ or retinoic acid. Conclusion: This novel gene expression signature may ultimately have utility in the clinical management of breast cancer radiotherapy patients.


Oral Abstracts

13

An Australian first guideline: Recommendations for the

An imaging evaluation of the simultaneously integrated

management of early breast cancer in women with an

boost (SIB) breast radiotherapy technique

identified BRCA1 or BRCA2 gene mutation or at high risk

J Turley

of a gene mutation

Chris O’Brien Lifehouse Radiation Oncology, New South

L Kenny,1 J Toohey,2 J Kirk,3 A Nelson,4 T Dalton,4

Wales, Australia

F Webster,4 O Care4 and H Zorbas4 1

Royal Brisbane and Women’s Hospital; Central Integrated

Regional Cancer Service, Brisbane, Queensland, Australia, 2

Sydney Breast Cancer Institute, New South Wales,

Australia, 3Familial Cancer Service, Westmead Hospital, Sydney, New South Wales, Australia, 4Cancer Australia, New South Wales, Australia Aim: Ensuring currency of cancer clinical practice guidelines is essential for making timely, evidence-based information available to health professionals. Approximately 5–10% of breast cancers are due to germline mutations in genes including BRCA1 and BRCA2.1 With input from key Australian stakeholders, we identified the management of early breast cancer in women with an identified BRCA1 or BRCA2 gene mutation or at high risk of a gene mutation as a priority area requiring updated clinical guidance. Method: A multidisciplinary working group was formed to develop the evidence-based clinical practice guideline. The guideline was based on a systematic review of the evidence covering research questions on surgical management, adjuvant and neoadjuvant systemic therapies and surgical risk-reducing strategies. Results: The guideline recommends that radiotherapy after breast conserving surgery in women diagnosed with breast cancer with a BRCA1 or BRCA2 mutation is offered to decrease the risk of ipsilateral breast cancer. The guideline also recommends that women diagnosed with breast cancer with a BRCA1 or BRCA 2 mutation are offered a choice of either breast-conserving treatment or mastectomy as both are effective in terms of survival. Clinicians should discuss contralateral risk-reducing mastectomy with these women to substantially decrease the risk of contralateral breast cancer. Clinicians should also discuss risk-reducing salpingo-oophorectomy with these women to improve overall survival and substantially decrease the risk of ovarian/fallopian tube cancer. The use and type of neoadjuvant/ adjuvant chemotherapy and of selective estrogen receptor modulators (SERMs) in women diagnosed with ER (estrogen receptor) positive breast cancer should be based on similar considerations for women with breast cancer and no BRCA1 or BRCA2 mutation. Conclusion: Cancer genetics is a rapidly emerging area and the guideline provides updated clinical guidance to assist clinicians with treatment recommendations for this unique group of women.

Aim: To evaluate the in-field megavoltage (MV) imaging of the SIB breast fields to determine its efficacy in treatment verification for the SIB breast radiotherapy technique. Method: During the course of treatment for 10 patients undergoing the SIB breast technique, in-field MV imaging of the SIB fields were acquired on days that regular treatment verification imaging (TVI) were performed. Wire was placed along the scar during simulation CT scanning of the patient and placed on the scar during TVI for offline matching purposes. The in-field images were then matched offline according to the scar wire on the digitally reconstructed radiograph (DRR). These images were assessed on their usefulness in measuring the SIB technique’s treatment accuracy. The offline image correction results were then applied to the Van Herk’s margin recipe formula as used by Van Herk et al.1 to calculate safe margins that account for the random and systematic uncertainties in position of the boost volume when an offline correction protocol has been applied. Results: After the offline assessment of the images acquired, 90 per cent were within our current department imaging protocol. Retrospectively, performing the maximum position deviations on the Eclipse treatment planning system demonstrated the CTV boost received a minimum dose percentage difference of −0.4%. Furthermore, applying our results to Van Herk’s margin formula (2.5□ + 0.7σ) as used by Van Herk et al.1 to ensure that 90% of patients receive 95% of the prescribed dose, the calculated CTV margins were comparable to the current department procedure used. Conclusion: Based on the in-field boost images acquired and the application of these results to the Van Herk margin formula, we can safely assume that the current CTV-PTV margins used are appropriate for the correct treatment of the SIB boost volume. Reference 1. Van Herk M, Remeijer P, Rasch C, Lebesque JV. The probability of correct target dosage: dose-population histograms for deriving treatment margins in radiotherapy. Int J Radiation Oncology Biol Phys 2000; 47 (4):1121–35.

Reference 1. Gage M, Wattendorf D, Henry LR. Translational advances regarding hereditary breast cancer syndromes. Journal of Surgical Oncology 2012; 105 (5):444–51.


14

Oral Abstracts

An audit of heart and lung doses for deep inspiration breath hold and free breathing left-sided whole breast

Thursday 4 September, 1030–1230 Concurrent Session: RANZCR Update

radiotherapy A Michalski, B Done, E Seymour, R David, F Hegi-Johnson,

Imaging guidelines – The RCR experience

A Windsor and K Nguyen

P Cavanagh

Central Coast Cancer Centre, Gosford Hospital, New South

Musgrove Park Hospital, Taunton, Somerset, UK

Wales, Australia Aim: The Central Coast Cancer Centre (CCCC) has clinically implemented deep inspiration breath hold (DIBH) for left-sided breast patients. This study aims to compare the heart and lung doses between DIBH and free breathing as a comparison to available Australian data. Method: At CCCC, all left-sided breast patients undergo a free breathing and DIBH scan. Standard tangential radiotherapy is planned on both scans to a prescription of 50 Gy in 25 fractions. The heart V25 Gy, mean and maximum radiation dose and distance in the treatment field are recorded as well as the V20 Gy, V30 Gy and mean ipsilateral lung dose. Treatment proceeded on the DIBH plan provided there was any reduction in dose to the heart and dose constraints to the lung were met. Results: Since implementation of the DIBH protocol in November 2013, three patients have been planned on the DIBH and free breathing scans. The doses to the heart and ipsilateral lung are presented in Table 1. Table 1. Heart and lung doses during DIBH and free breathing left sided breast radiotherapy Organ

Constraint

DIBH

Free breathing

Heart

V25 Gy (%) Mean (Gy) Maximum (Gy) Max heart distance (cm) V20 Gy (%) V30 Gy (%) Mean (Gy)

0.69 1.3 42.1 0.6 14.5 13.0 8.2

7.3 4.8 52.3 2.3 17.2 15.6 9.4

Ipsilateral lung

Aim: This presentation will outline the role the Royal College of Radiologists of the UK has had in the development and use of referral guidelines in diagnostic radiology over the last 20 years and highlight the learning that is now influencing our current approach. It will cover the motivation to produce guidelines and the challenges faced in the production and utilisation of the current version “IRefer”. The final section will take the lessons from the experience so far and suggest potential directions for the future. The main initial drive for guideline production was the need to ensure patients’ exposure to ionising radiation was appropriate. During this period there has been a major expansion in the number of guidelines produced in each edition with a developing sophistication of the review methodology and the focus is far more on the ensuring the right test at the right point in the patient pathway. The key challenge in production has been the resource intensity of this process and the heavy reliance on the goodwill and commitment of members of the college. Ensuring referrers actually use guidelines is becoming the major obstacle to their effective usage, although the presentation will reference recent audits that show appropriate use of the latest edition in certain situations can be achieved by active justification To solve the challenge of usage, the RCR believes that IRefer must be freely available at the point of referral and this would be most effectively delivered by the use of decision support algorithms embedded in the order-communication systems that are now regularly used. Options for how this would be achieved will be considered as well other drives for improved utilisation including education and feedback, incentives and sanctions.

For all patients, the DIBH plan resulted in a reduction in heart dose, with one patient resulting in a slight increase in lung dose. Conclusion: DIBH results in a large reduction in all heart dose constraints and a moderate reduction in lung dose, which is comparable to results reported in the literature1. The results from a larger prospective cohort of patients will further statistically validate the results from this study. Reference 1. Hayden AJ, Rains M, Tiver K. Deep inspiration breath hold technique reduces heart dose from radiotherapy for left-sided breast cancer. Journal of Medical Imaging and Radiation Oncology 2012 August; 56 (4):464–72.


Oral Abstracts

15

Network radiology and teleradiology: The changing

RaER 2014: Update on incident reporting in radiology

practice of radiology

C Mandel

F Parrish

Peter MacCallum Cancer Centre, East Melbourne, Australia

I-TeleRAD, Melbourne, Australia The advancement of radiology from film (analogue) to a digital environment is almost complete within the Australasian environment. This talk will examine the processes and challenges of digital radiology and discuss further potential changes in the practice of radiology in Australasia.

Aim: Incident reporting is an integral part of any safety system. Generic healthcare incident reporting systems do not always reflect the needs of radiology. The Radiology Events Register (RaER) is a radiology-specific incident reporting database established in 2006 by the Royal Australian and New Zealand College of Radiologists and funded by the Australian Federal Government’s Department of Health and Ageing. This paper presents current developments in RaER, a summary of the data that has been collected so far, and a comparison with selected incident reporting systems elsewhere. Method: The database has been reviewed to present the current numbers of reports, sources, and trends. Radiology incident reporting initiatives and results from selected other regions were reviewed to determine similarities with and differences from RaER. Results: Over 4000 incidents have been recorded, including those derived from data sharing with medical defence organisations, state health departments and radiation regulation authorities. In July 2013 the reporting interface was upgraded and a new website launched (www.raer.org.au). The number of incidents being reported is increasing slowly, by approximately 20/month, mostly from trainee reports. Given the large numbers of tests and treatments provided by radiologists and the small number of reports recorded, many incidents are either not recognised or not recorded. Other incident reporting systems either restrict access to published information to members via password-protected log in or only look at restricted areas, such as radiation incidents and are, therefore, neither comprehensive in scope nor reach. Case reports are being used to highlight problems identified and provide a platform to provide education and information to radiologists and others working in medical imaging. Conclusion: Incident reporting is a key element of a patient safety system. Developing an understanding of its importance and value is part of creating a safety culture which, ultimately, increases safety in healthcare.


16

Thursday 4 September, 1030–1230 Proffered Papers: Brachytherapy

Oral Abstracts Clinical implementation of in vivo source position verification for high dose rate (HDR) prostate brachytherapy using a flat panel imager

Advances in brachytherapy – So why the decline in

R Smith,1,3 J Millar,1,3 B Matheson,1 B Hindson,1

utilisation?

A Haworth,2,3 M Taylor,3 L McDermott3 and R Franich3

A Haworth1,2 1

Peter MacCallum Cancer Centre, Melbourne, Victoria,

1

William Buckland Radiotherapy Centre, The Alfred Hospital,

Melbourne, Australia, 2Physical Sciences, Peter MacCallum

Australia, 2Sir Peter Mac Department of Oncology, University

Cancer Centre, East Melbourne, Australia, 3School of

of Melbourne, Melbourne, Victoria, Australia

Applied Sciences, RMIT University, Melbourne, Australia

Aim: Exciting advances in technology provide increasing opportunities for external beam radiotherapy (EBRT) to safely deliver tightly conformal fields in smaller numbers of fractions. But we’ve been doing this in brachytherapy (BT) for a long time. So, why is the utilisation of BT declining worldwide? Method: The technology behind the delivery of BT treatments is relatively simple and cheap compared with EBRT. For appropriately selected patients, treatments are effective and safe when delivered by appropriately trained and experienced teams. Several publications have reported alarming declines in the use of brachytherapy(1,2) Results: In a review of >1800 publications, Grimm et al.(3) noted brachytherapy for appropriately selected prostate cancer patients offers superior clinical outcomes compared with EBRT. This presentation will question ‘Do we need more technology in brachytherapy to reverse the decline in utilisation?’ It will also review recent developments in introducing advanced imaging techniques into brachytherapy, advanced dose calculation algorithms, new treatment approaches such as focal treatments for prostate cancer, the use of robotic systems to accurately deliver LDR radioactive sources, and advancements in in-vivo dosimetry systems to provide real-time assurance of treatment delivery accuracy. Conclusion: Escalating costs in healthcare are a worldwide concern, yet declining rates of brachytherapy have been reported despite the proven effectiveness of relatively simple, low-cost, low-technology brachytherapy options. We question the reasons why, and ask if broadening the education of health professionals along with the offer of automated systems has the potential to reverse these trends.

Aim: To clinically implement our novel position-sensitive sourcetracking system based on a flat panel imager. Method: We monitored the treatment delivery of four prostate HDR brachytherapy patients (eight treatment fractions) in this initial study. The imaging system, mounted under carbon fibre couch top (Fig. 1), was used to image the implant with x-ray dwell position markers and then HDR source dwells during delivery. The images acquired were processed to determine the position of the source in the patient. Source positions measured were compared to the treatment plan for verification. Results: Relative dwell spacing within and between catheters in the coronal plane were verified, typically within 2.0 mm (0.2 mm–3.3 mm, s.d. 0.8 mm) of the planned positions (Fig. 2). Discrimination between larger dwell intervals and catheter differentiation was clear. Important delivery attributes were confirmed, such as correct transfer tube connection, source step size, relative catheter positions and therefore overall correct plan delivery. Conclusion: The novel, non-invasive HDR brachytherapy treatment verification system was used clinically with minor impact on workflow. The system allows verification of correct treatment delivery, free of most potential human-related errors identified in ICRP 97.

References 1. Han K et al. Trends in the utilization of brachytherapy in cervical cancer in the United States. Int J Radiat Oncol Biol Phys 2013 Sep 1; 87 (1): 111–9. 2. Martin JM et al. The rise and fall of prostate brachytherapy: Use of brachytherapy for the treatment of localized prostate cancer in the National Cancer Data Base. Cancer 2014 Apr 15; 120 (14): 2114– 2121. 3. Grimm P et al. Comparative analysis of prostate-specific antigen free survival outcomes for patients with low, intermediate and high risk prostate cancer treatment by radical therapy. Results from the Prostate Cancer Results Study Group. BJU Int 2012 Feb; 109 (Suppl 1): 22–9.

Patient Implant

Couch Top

Pelvis

*

Legs

Flat Panel Imager

Fig. 1. Geometry of imaging system relative to implant.


Oral Abstracts

17 Phase I/II clinical trial of a 3D real-time array dosimeter to determine in vivo the dose to the rectum for pelvic brachytherapy N Suchowerska,1,2 P Liu,2 C Milross,1,2 J Toohey1 and D McKenzie2 1

Radiation Oncology, Chris O’Brien Lifehouse, New South

Wales, Australia, 2School of Physics, University of Sydney, New South Wales, Australia

Fig. 2. Measurement vs plan for 2 dwells in each of 5 catheters from a patient treatment fraction.

Aim: Radiation proctitis can occur years after radiotherapy, accounting for over 75% of gastrointestinal injury. Patient embarrassment leads to under-reporting, despite the profound impact these symptoms cause on quality of life. Consequently, clinicians frequently constrain the prescribed dose in pelvic radiotherapy to spare the rectum. As a dose limiting structure, any uncertainty in the rectal dose is a barrier to dose escalation and improvement of patient outcomes. We will report on the use of a customised rectal applicator with embedded dosimeters to measure the dose to the rectal wall in order to validate the delivery of the prescribed treatment and to avoid the risk of an undesirably high rectal dose or even a radiation accident. Method: An array of scintillation dosimeters was positioned in a rectal phantom applicator designed in a CAD program and built using Objet 3D printing. A lumen in the centre of the applicator permitted a five diode array to be inserted. The scintillation dosimeters were optically interfaced to an array of photomultiplier tubes kept outside the treatment room. LabVIEW software was used to record the dose for a range of real-time displays. Results: The dose profiles along the anterior, posterior, right and left lateral walls of the rectum were recorded in real time for 10 gynaecological insertions with a Nucletron HDR (Ir192) afterloader. On the completion of treatment, the measured doses were found to be consistent with those of the rectal diodes. Conclusion: The 3D array system enabled definitive in-vivo dosimetric assessment, with high spatial resolution, alerting intervention if required and was well tolerated by patients. The measured dose distribution provides valuable input data to correlate subsequent organ at risk complications with the actual pattern of dose deposition. Planned improvements in HDR practice will use the dosimeter array as both a dosimeter and imaging reference. The authors acknowledge funding from an NHMRC project grant.


18

Oral Abstracts

Pre-treatment verification in HDR brachytherapy at the

Biologically based inverse planning for low dose rate

Chris O’Brien Lifehouse: Physics experience

boost focal brachytherapy of the prostate

M Whitaker, A Lovett, S Kaldas, R Hill and G Hruby

A Haworth,1,2 C Mears,3 H Reynolds,1,2 J Betts,3 G Tack,3

Chris O’Brien Lifehouse, New South Wales, Australia Aim: Mis-administrations in high dose rate (HDR) brachytherapy are often errors in procedure prior to treatment.1 Other sources of error in the planning and treatment delivery of brachytherapy have largely been well documented and managed.2,3,4 However, procedural errors prior to treatment are difficult to eliminate due to the human factor but may be mitigated by appropriate protocols and the training of personnel involved in the treatment process.2,3 At the Chris O’Brien Lifehouse, a transitioning environment led to the review and update of our current pre-treatment verification procedures. The role of the medical physicist in designing and developing a pre-treatment verification procedure is integral to the maintenance of quality and safety of the treatment.2,3 Method: The multidisciplinary brachytherapy group reviewed all treatment sites to identify the sensitive points at which procedural errors could potentially occur. This included a review of the current protocols for each site, a systematic approach in assessing the hazards and determining associated risks. The medical physics staff identified hazards by the possibility of an error occurring due to the lack of a record and verify system, and its risk was assigned by the likelihood of the error occurring. Results: Protocols and procedures were re-designed and a number of pre-treatment tasks were identified to be performed by the medical physicist to minimise risks. In this high-consequence environment, it is essential that medical physicists be familiar with all aspects of the end-to-end treatment process in order to provide meaningful contributions. Conclusion: Sensitive points within our brachytherapy treatment have been identified and managed through the design and documentation of revised pre-treatment verification protocols for all sites treated. The advantage of a multidisciplinary group approach cannot be overstated in the risk management process, and a culture of safety and quality management is essential for all staff groups involved in patient treatment. References 1. Thomadsen B, Lin S-W, Laemmrich P et al. Analysis of treatment delivery errors in brachytherapy using formal risk analysis techniques. Int J Radiat Oncol Biol Phys 2003; 57 (5): 1492–1508. 2. Valentin J (ed). ICRP Publication 97: Prevention of High-Dose-Rate Brachytherapy Accidents. Elsevier, Amsterdam, 2005. 3. Gerbaulet A, Potter R, Mazeron J-J, Meertens H, Van Limbergen E. The GEC ESTRO Handbook of Brachytherapy. ESTRO, Brussels, 2002. 4. Dempsey C, Smith R, Nyathi T et al. ACPSEM brachytherapy working group recommendations for quality assurance in brachytherapy. APESM 2013 December; 36 (4): 387–96.

K Kevin3 and M Ebert4,5 1

Peter MacCallum Cancer Centre, Victoria, Australia,

2

Sir Peter Mac Department of Oncology, University of

Melbourne, Melbourne, Victoria, Australia, 3Faculty of Information Technology, Monash University, Victoria, Australia, 4Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, 5School of Physics, University of Western Australia, Western Australia, Australia Aim: To demonstrate the application of a biologically based inverse optimisation algorithm to achieve high rates of tumour control probability (TCP) with minimal dose to normal tissues. Method: The treatment plans for 10 patients treated with a conventional approach to low dose rate brachytherapy (LDR, 145 Gy to entire prostate) were compared with plans for the same patients created with a biologically based inverse optimisation planning process. The biological optimisation considered a non-uniform distribution of tumour cell density through the prostate based on known and expected locations of tumour(1). A range of optimisation objectives were considered based on maximising the TCP and minimising dose to the urethra and the volume of tissue posterior to the prostate. The robustness of the plans was tested in the presence of random and systematic displacement of seeds. Results: Initial results indicate that on average, the volume of the urethra receiving 125% of the conventional dose prescription (145 Gy) may be reduced from 64% to 40% while maintaining high values of TCP through use of a biological optimisation approach. With this conservative approach, the average number of planned seeds was reduced from 85 to 73 and in all cases; the robustness of the plans was not inferior to the conventional plans when considering clinically realistic seed displacements. Future work will incorporate functional imaging techniques to populate the radiobiological model with patientspecific tumour characteristics. Conclusion: A biologically based inverse planning approach to LDR treatments has the potential to maintain high rates of tumour control while minimising dose to healthy tissue. Reference 1. Haworth A, Williams S, Reynolds H, Waterhouse D, Duchesne GM, Bucci J et al. Validation of a radiobiological model for low-dose-rate prostate boost focal therapy treatment planning. Brachytherapy 2013 Nov–Dec; 12 (6): 628–36.


Oral Abstracts Simulated learning in emergency training for high dose rate brachytherapy

19

Thursday 4 September, 1030–1230 Proffered Papers: Detectors and QA

Y Tran, T Nguyen and V Seshadri Epworth Radiation Oncology, New South Wales, Australia

A commissioning standards analysis of static and rotational beam deliveries using a commercial diode

Aim: During a high dose rate (HDR) brachytherapy treatment, the likelihood of the source failing to retract or source detachment is very low due to the safety mechanisms built into the HDR unit. However, AAPM TG 591 recommends that all departments providing HDR brachytherapy should have emergency procedures in place and routinely test and practice the procedures. A simulated learning programme has been developed to provide training and feedback to the brachytherapy staff in the case of an HDR emergency. Method: Using a Laerdal SimMan Essential Patient Simulator™, an HDR emergency was simulated with the Nucletron® applicator and remote afterloader. The simulation was recorded on five cameras, with four members of the brachytherapy team performing the documented emergency procedure. Critical review of the simulation was undertaken against the documented procedure and feedback provided to staff between each simulation. Results: Four simulations were carried out and after each simulation, a debriefing took place. Gaps within the emergency procedures were identified and processes were instigated to improve and refine the emergency procedures. Reviewing the simulations, it was clear that staff movement throughout the emergency situation required improvement and highlighting the importance of communication. The sequential simulations and feedback loop enabled an improvement to total emergency response time of 18% from the first to final simulation. Conclusion: HDR remote afterloader systems are designed to minimise the possibility of non-retraction of the 192Ir source; however, staff must be well versed in the emergency procedure with regular training sessions. A simulated learning programme has been developed that can provide feedback on timeliness, success and potential improvement in the emergency system. Using simulation is a novel learning tool for brachytherapy avoiding dose to staff and patients. Reference 1. Kubo HD, Glasgow GP, Pethel TD, Thomadsen BR, Williamson JF. High dose-rate brachytherapy treatment delivery: Report of the AAPM Radiation Therapy Committee Task Group No. 59. Medical Physics 1998; 25 (4): 375–403.

array dosimetry system M Gargett,1 J McNamara,2 M Bailey,3 P Metcalfe1 and M Carolan3 1

Centre for Medical Radiation Physics, University of

Wollongong, New South Wales, Australia, 2Shoalhaven Cancer Care Centre, New South Wales, Australia, 3Illawarra Cancer Care Centre, Wollongong Hospital, New South Wales, Australia Aim: To use a diode array dosimetry system to assess external beam radiation therapy planning and delivery chains. Method: The Delta4® (ScandiDos) was used to assess static (IMRT) and rotational 6 MV linac beam delivery using tests outlined in the AAPM Task Group 119 document.[1] The tests are designed to simulate common clinical scenarios, covering both the planning and delivery aspects of treatment. There are set dose contours of target and normal structures as well as beam arrangements to be adhered to. A benchmark standard for IMRT commissioning is defined in the document according to a confidence limit, which was calculated based on the outcome of these tests (see Equation 1, where ‘mean’ refers to the average gamma pass rate and σ is the standard deviation). Ionisation chamber measurements were performed concurrently using a cc13 chamber (Scanditronix/Wellhofer). Plans were generated using Pinnacle3® Radiation Therapy Planning software v.9.0 (Philips Radiation Oncology Systems).

CL = 100 − Mean + 1.96σ

(1)

Results: The confidence limit for IMRT commissioning, calculated using the Delta4® dosimetry system, is outlined in Table 1. The locally obtained confidence limit (1.6%) was confirmed by ionisation chamber measurements (1.4%). The confidence limit is well within the bounds stated in the TG119 document (7%) for adequate commissioning of IMRT delivery. Results for rotational delivery also adhere to this standard with a confidence limit of 0.1% obtained using the Delta4®, although ionisation chamber measurements suggest a confidence limit of 1.3%. Table 1. IMRT confidence limit, where the “overall” value is an average of Delta4 ® results for all plans. Results published in the AAPM report are included for comparison.[1] Plan Multitarget Mock prostate Mock H&N C-shape Overall CL

Local mean

Local σ

99.3 0.1 98.9 0.3 99.0 1.3 99.9 0.1 99.3 0.4 1.6 (98.4% passing)

TG119 mean

TG119 σ

97.8 3.5 98.6 2.4 98.1 2 97.4 2.8 97.9 2.5 7 (93% passing)

Conclusion: Results obtained using the Delta4® dosimetry system were well within the confidence limits specified by the TG119 document, confirming a satisfactory commissioning standard for IMRT at our local centre. The confidence limits calculated locally for dynamic


20

rotational deliveries are small and comparable to those obtained for IMRT, implying the dynamic approach does not impede the accurate delivery of planned dose distributions. Reference 1. Ezzell, Burmeister, Dogan et al. IMRT commissioning: multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119. Medical Physics 2009 October 27; 36: 5359–73.

Oral Abstracts A novel automated method of linac source alignment QA J Chojnowski Crown Princess Mary Cancer Centre, Westmead, New South Wales, Australia Aim: To facilitate the process of verifying the coincidence of radiation and mechanical isocentres. Method: One of the recommended annual tests for medical linear accelerators (e.g. in TG-142) is the verification of coincidence of radiation and mechanical isocentres. In general, it is a time-consuming test that requires a mechanical pointer and performing many mechanical rotations of the collimator, gantry and couch. Analysis of this test reveals that the best match of two isocentres occurs only when there is perfect alignment of the radiation source position with the collimator axis of rotation. If the radiation source is aligned with the collimator axis of rotation, then the radiation isocentre position determined by the collimator rotation (star shots) is independent of the type of field collimation used: Jaws or MLCs. However, if the radiation source is misaligned with the collimator axis of rotation then the radiation isocentre position does depend on the type of collimation (see Fig. 1), because the physical position and distance of Jaws and MLCs are different in relation to the radiation source. The misalignment of the radiation source can be determined from two parameters. The first one is a constant value (for the particular linac model) and depends on the linac head geometry only, while the second depends on the difference between two radiation isocentres defined by XY jaws and MLC respectively. The proposed method utilises the EPID and in-house developed image analysis software to determine the value of the second parameter. Results: The QA results of linac source misalignment of three linacs at our department are on average 0.07 mm ± 0.04 mm (one standard deviation) (a fourth linac has significantly larger misalignment of 0.46 mm). The new method has been compared with an independent chamber-based method and agreed within ± 0.01 mm. Conclusion: An automated method of linac source alignment QA using the EPID is very quick and accurate and it gives equivalent results to verifying the coincidence of radiation and mechanical isocentres by traditional, manual methods.

Fig. 1. An example of the source misalignment error (6 MV) based on measured linac radiation isocentres defined by XY JAWS and MLC on a Varian 21iX linac.


Oral Abstracts

21

Effects of changing modulation factor and pitch

Characterisation of GafchromicTM EBT3 dosimetric film for

parameters on tomotherapy delivery quality

use at high dose levels in commissioning of radiosurgery

assurance plans

R Jones,1 R Artschan,1 D Thwaites2 and J Lehmann1,2

D Binny, S Sylvander, C Lancaster and S Harris

1

Royal Brisbane and Women’s Hospital, Queensland,

Newcastle, New South Wales, Australia, 2Institute of Medical

Australia

Physics, University of Sydney, New South Wales, Australia

Aim: To investigate delivery quality assurance (DQA) discrepancies observed for helical tomotherapy plans Method: Six tomotherapy plans that initially failed gamma analysis using film were selected for this investigation. While most plans passed ion chamber measurements (IC) for a set tolerance of 3%, the fluence analysis showed larger deviations from the 3% 3 mm gamma tolerance. Each plan was then re-optimised and batch processed using increasing and decreasing values of modulation factors (MF) and pitch to reassess the fluence in a circumferential plane using the Sun Nuclear ArcCheck diode array. Point doses, fluences, leaf opening times (LOT), sinograms and conformities were compared for each DQA plan. In order to ensure that the treatment constraints remained the same, the dose volume histograms (DVHs) of all the modulated plans were compared to the initially approved plan. Patient sites like breast, prostate, abdomen and brain were included in this study. Results: In contrast to the vendor’s recommendation, it was observed that increasing modulation factors did not significantly improve DVH uniformity but reduced the set fluence pass rates. This increased treatment time and delivery monitor units by decreasing the ratio of multiple leaf collimators maximum to mean LOTs. Also, decreasing the pitch did not always reduce treatment time and delivery accuracy as many other factors like complexity of treatment plan, and treatment area played an important role. Conclusion: The impact of leaf timing inaccuracies on plans with higher MFs that had larger mean LOTs were seen to be significant. Point dose measurements were seen to be within ±3% for all plans except for one where the largest MF was chosen. Slight increase in MF does improve plan delivery quality. Conformity analysis of plans with increasing MF showed small variations in the isodose distribution for plans even when no changes were made to the actual planning constraints.

Aim: A robust tool is required for the dosimetric verification of high dose small fields associated with stereotactic radiosurgery (SRS) and hypo-fractionated radiotherapy (SRT). The response characteristics of EBT3 have been determined for the high dose range. The application of the film in SRS/SRT quality assurance testing has been evaluated. Method: The response characteristics of EBT3 (Lot# 07221303) were examined using an Epson Expression 10000XL flatbed scanner in combination with ImageJ and RIT software. Red, green and blue channel responses were analysed for 0–40 Gy. Green channel inter and intra film uniformity, dose rate dependence and post exposure darkening were characterised at high doses. Film uniformity was compared using two films from the same batch, each divided into 16 equal pieces and irradiated with 15 Gy. The characterisation was complemented by verifying a cranial SRS treatment with the film positioned in a LucyTM phantom. Results: The dose response curves of the three colour channels were compared across a 0–40 Gy dose range. Green channel analysis was found to be optimal for doses above 10 Gy due to its wider dynamic range. The dose response curves of two 6 MV beams delivered at 1000 MU/min and 600 MU/min rep rate across a 0–40 Gy dose range were found to agree with a maximum variation of 1.3%. The postirradiation darkening of EBT3 for 10, 15 and 25 Gy was determined. The dose distribution of an iPlanTM SRS treatment was verified. Conclusion: The new generation EBT3 film is suitable for use with high doses up to the manufacturer’s recommended limit of 40 Gy. Analysis with the green channel is recommended. Calibration at the dose rate used for delivery should be considered.

Department of Radiation Oncology Calvary Mater


22

Oral Abstracts

Dosimetric verification of prostate VMAT SBRT boost

Patient plan-specific quality assurance using Gafchromic

using a new 3D EPID method

EBT3 film for VMAT hippocampal avoidance whole brain

K Legge, P Greer and J O’Connor

radiotherapy

University of Newcastle, New South Wales, Australia

S Roderick and A Quinn Radiation Oncology, Royal North Shore Hospital, New South

Aim: The PROMETHEUS trial proposes to deliver a prostate radiotherapy boost consisting of two 9.5 Gy fractions using stereotactic body radiation therapy (SBRT). Careful quality assurance of this boost dose is required to ensure patient safety. The aim of this work is to verify the three-dimensional (3D) SBRT dosimetry using an electronic portal dosimetry (EPID) technique. Method: The EPID method derives a 3D composite dose distribution in a virtual water-equivalent cylindrical phantom from EPID images measured in air. It uses correction of backscatter artefacts produced by the EPID support arm, conversion to fluence and then calculation of dose in the phantom. The 3D dose is compared to a treatment planning system verification plan calculated on the phantom. A patient SBRT plan was delivered and cine images acquired, each image with the average of 12 frames. Individual frames from a research framegrabber system were also acquired for comparison. The 3D dose was constructed from the cine images and compared to the treatment planning system dose. Results: The isocentre dose from the EPID method was 1.7% higher than the Eclipse dose. Gamma comparisons using 2D coronal, sagittal and axial dose planes through the isocentre gave pass rates over 98.8% (3%, 3 mm, 10% threshold). When compared to the images acquired with the framegrabber, it was found that four cine image frames were dropped and this must be accounted for in the EPID to dose conversion. Conclusion: A quality assurance method has been developed for use on an SBRT prostate boost using 3D EPID dosimetry. This will be supported with in-vivo dosimetry measurements and on-line real-time IGRT during patient treatment. The technique used here should also be applicable to other centres in this trial where cine-imaging with EPID is available.

Wales, Australia Aim: Hippocampal avoidance whole brain radiotherapy for brain metastases is treated at NSCC with an adaptation of RTOG-0933 using a VMAT technique with two full arcs in neutral couch position and one apex arc. This protocol limits dose to the centrally located hippocampal region of the brain to 6 months, n = 2), there is evidence of further delayed local dose effects compared to 3-month SPECT/CT.


Oral Abstracts

25 Reducing imaging dose in 4D cone-beam computed tomography using patient respiratory signals B Cooper,1,2 R O’Brien,2 J Kipritidis2 and P Keall2 1

The Canberra Hospital, Australian Capital Territory,

Australia, 2The University of Sydney, New South Wales, Australia

Conclusion: This study presents evidence showing the effects of local tissue sparing in low dose regions and preserved global kidney function after SABR to primary RCC. There is a relationship between lost renal cortical function and volume of highly-irradiated tissue. Greater global loss in renal function was observed in patients prescribed 42 Gy in three fractions compared to a single fraction of 26 Gy.

Aim: Radiotherapy patients who undergo thoracic 4D cone-beam CT receive an unwanted but necessary imaging dose. This work takes that patient’s respiratory signal to drive the 4D CBCT image acquisition using a “respiratory triggered 4D CBCT” (RT 4D CBCT) technique1 with the goal of reducing the necessary imaging dose and maintaining image quality. Method: Image acquisition simulations using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique were generated from a database of oversampled Rando phantom CBCT projections. One-hundred-and-eleven free breathing lung cancer patient respiratory signal files were used to create matching pairs of RT 4D CBCT and conventional 4D CBCT image datasets from realistic simulations of a 4D RT CBCT system. Each of these image datasets were compared to a ground truth dataset from which a root mean square error (RMSE) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation was counted and is assumed as a surrogate for imaging dose. Results: RT 4D CBCT gave an average imaging dose reduction of 53% based on needing fewer projections (average 617, Fig. 1a) compared to conventional 4D CBCT (1320 projections, Fig. 1b) and image quality was minimally reduced by 7.6%. Conclusion: The simulation studies, using a wide range of patient breathing traces, have demonstrated that the RT 4D CBCT method can potentially offer an average saving in imaging dose of 53% compared to conventional 4D CBCT with a small impact on image quality.

References 1. Scheenstra AEH, Rossi MGR, Belderbos JSA, Damen EMF, Lebesque JV, Sonke JJ. Local dose-effect relations for lung perfusion post stereotactic body radiotherapy. Radiotherapy and Oncology 2013; 107: 398–402. 2. Goshar D, Embon OM, Frenkel A, Front D. Renal function and technetium-99m-dimercaptosuccinic acid uptake in single kidneys: the value of in vivo SPECT quantitation. Journal of Nuclear Medicine 1991; 32 (5):766–8.

Fig. 1a. 617.


26

Oral Abstracts Co-registration of V-SPECT and radiotherapy planning CT: Evaluation of pre- and post-stereotactic ablative body radiotherapy treatment scans for lung cancer patients K West,1 J Barber1 and F Hegi1,2

Fig. 1b. 1320. Reference 1 Cooper BJ, O’Brien RT, Balik S, Hugo GD, Keall PJ. Respiratory triggered 4D cone-beam computed tomography: A novel method to reduce imaging dose. Medical Physics 2013; 40: p041901.

1

Nepean Cancer Care Centre, New South Wales, Australia,

2

Central Coast Cancer Care, New South Wales, Australia

Aim: To determine if Technegas Ventilation Single Photon Emission Computed Tomography (V-SPECT) scans can successfully be registered with radiotherapy planning Computed Tomography (CT) and identifying the potential uses of the co-registration in relation to radiation therapy sequelae. Method: Five patients treated with Stereotactic Ablative Body Radiotherapy (SABR) ,for non small cell lung cancer, at Nepean Cancer Care Centre were scanned pre-treatment with a 4D planning CT and were also sent for a V-SPECT scan to determine lung function. After the completion of radiotherapy, a follow up V-SPECT scan was performed. Imaging data were transferred into VelocityAI (Velocity Medical Systems), an image registration program used in both radiotherapy and medical imaging, and each patient was evaluated in relation to lung function and treatment area. Dose related outcomes (changes in function against planned dose) were examined and the role of V-SPECT as a tool for personalised radiotherapy planning evaluated. Results: V-SPECT scans were successfully registered to the average intensity projection of the planning CT, using B-Spline deformable image registration. High and low functioning regions of lung were defined globally, and locally in the treatment area. Changes in ventilation related to the treatment plan is at this stage inconclusive – initial results show moderate correlation across V-SPECT time series and weak correlation of changes in lung ventilation with treatment dose. Conclusion: A series of V-SPECT scans can be used to track lung function and its changes. Future use of this information will look at whether pre-treatment scans can indicate likely radiation therapy sequelae, with the goal of function-guided radiotherapy planning.


Impact of MRI geometric distortion on tangential IMRT 4

breast plans A Walker,1,2,3 V Batumalai,2,4 K Dundas,1,2,3 G Delaney,2,4,6,7

13.6 G% 25.4% 2.3 Gy 8.4 Gy*

27

81.5% 52.8 Gy

Oral Abstracts

M Boxer,2,6 E Koh,2,4,7 M Yap,2,3,4,6,7 P Metcalfe,1,2,3

Research, Liverpool Hospital, Sydney, New South Wales, Australia, 4University of New South Wales, Sydney, New South Wales, Australia, 5Institute of Medical Physics, School of Physics, University of Sydney, Sydney, New South Wales,

3

7.2% 15.4% 3.4 Gy 3.8 Gy

Liverpool and Macarthur Cancer Therapy Centres, New

South Wales, Australia, 3Ingham Institute for Applied Medical

15.8% 31.5% 1.4 Gy 4.2 Gy

2

2

Wollongong, Wollongong, New South Wales, Australia,

95.4% 54.2 Gy

Centre for Medical Radiation Physics, University of

‘Distorted’ plan on original CT

1

93.4% 53.1 Gy

G Liney,1,2,3,5 J Dowling8 and L Holloway1,2,3,4,5

Australia, 6Collaboration for Cancer Outcomes Research and Evaluation, Liverpool Hospital, Liverpool, New South

9.6% 20.5% 1.5 Gy 4.0 Gy *Exceeded both ideal and acceptable criteria limits.

8.4% 16.7% 3.8 Gy 4.6 Gy 17.1% 33.1% 1.4 Gy 4.4 Gy 8.0% 19.0% 0.8 Gy 3.0 Gy

96.6% 54.4 Gy 97.0% 54.3 Gy 97.7% 56.4 Gy

PTV prescription ≥95% of PTV ≥ 47.5 Gy Maximal 1 cc ≤ 55 Gy Constraints ≤15% Ipsilateral lung ≥ 20 Gy ≤50% Ipsilateral lung ≥ 5 Gy Heart, mean ≤ 4 Gy Contralateral breast, max 1 cc ≤ 3.1 Gy

3 1

Plan on distorted CT Dose Criteria Prescription 50 Gy

Table 1: DVH data for plans created on the distorted CT and that plan on the original CT

Aim: Geometric distortions in magnetic resonance imaging (MRI) present a potential technical barrier in its widespread application in radiotherapy treatment planning. The aim of this retrospective study is to investigate the impact of geometric distortion on whole breast supine radiotherapy treatment plans. Method: A grid phantom developed for determining MRI distortion was scanned on a Siemens 3T Skyra with a spin echo (SE) sequence and a CT scanner. The CT and MR images were non-rigidly registered to obtain a deformation field representing geometric distortion. This field was then applied to four original breast CT datasets with corresponding contours. Tangential IMRT plans were created on the distorted CT images to mimic planning from MR images (the intended plan). These plans were then transferred to the original CT images to identify dosimetric differences due to geometric distortion (the delivered plan) and all plans were reviewed by four radiation oncologists. Results: Geometric distortion in the SE sequence ranged from 0–8.5 mm, with distortions greatest in the peripheral FOV. Planning target volume (PTV) coverage was compromised with the delivered plans (Table 1). Patients with the larger separation (patients 2,3) had the smallest reduction in PTV coverage with the delivered plan still within dose criteria limits and doses to organs at risk (OAR) reduced. The largest reduction in PTV coverage and a large increase in OAR dose was seen in the smallest patient (patient 4), despite the distortions observed being smaller within the image for this patient. Delivered and intended plans were only assessed as comparable for patients 1 and 2. Conclusion: Preliminary results have indicated that clinically significant differences may occur between delivered and planned (intended) dose distributions when treatment plans are created using geometrically distorted MR images. Variations depend on patient size, shape and target and OAR volumes. A more extensive investigation is ongoing.

4

Research Centre, Brisbane, Queensland, Australia

96.0% 53.3 Gy

Patient

Organisation Computational Informatics, Australian E-Health

8.1% 19.0% 0.9 Gy 3.0 Gy

Commonwealth Scientific and Industrial Research

2

8

1

Sydney, Sydney, New South Wales, Australia,

96.9% 56.6 Gy

Wales, Australia, 7School of Medicine, University of Western


28

Oral Abstracts

Quantifying prostate and lung tumour rotation using

Radiosurgery beyond cancer: Real-time target localisa-

kilovoltage intrafraction monitoring

tion and treatment planning for cardiac radiosurgery

C Huang,1 J Tehrani,1 J Booth2 and P Keall1

under MRI guidance

1

The University of Sydney, 2Royal North Shore Hospital,

New South Wales, Australia

S Ipsen,1,6 O Blanck,2 B Oborn,3 F Bode,4 G Liney5 and P Keall6 1

University of Luebeck, Germany, 2University Clinic

Aim: Tumour positional uncertainty is a major issue that deteriorates the efficacy of radiotherapy. Tumour rotational movement which is not well understood can result in significant geometric and dosimetric inaccuracies. The objective of this study is to investigate prostate and lung tumour rotation by utilising a novel tumour monitoring method known as kilovoltage intrafraction monitoring (KIM)[1]. Method: Intrafractional tumour rotation was calculated for 267 fractions over 10 prostate patients and 50 fractions over three lung patients. Continuous kilovoltage (kV) projections on tumour with gold fiducial markers were acquired during radiotherapy for 10 prostate patients and immediately prior or after radiotherapy when patients were on couch for three lung patients. Marker 2D position and 3D coordinates were determined by KIM. Rotations about each axis (LR, SI and AP) with the centroid of the markers as the pivot were then calculated using the iterative closest point algorithm. Different methods and thresholds were applied to accept data and filter noise. Results: There were large variations in the magnitude of the tumour rotation among different fractions and patients. Various rotational types were observed. Rotation about LR was predominant among three axes for prostate patients and SI for lung patients. The average prostate rotation angles around the LR, SI and AP axes were 1.0 ± 5.0, 0.6 ± 3.3 and 0.3 ± 2.0 degrees respectively. For lung patients, the average LR, SI and AP rotation angles were found to be 0.8 ± 4.2, −0.8 ± 4.5 and 1.7 ± 3.1 degrees respectively. Conclusion: For the first time, continuous tumour rotation has been calculated utilising the KIM method. In prostate and lung cancer patients, tumours were found to undergo rotations of more than 5° for almost a third of the total treatment/imaging time indicating the need for intrafractional adaptation during radiation delivery. Using the KIM method, real-time tumour rotation adaptation would reduce treatment margins [2]. References 1. Ng JA et al. Kilovoltage intrafraction monitoring for prostate intensity modulated arc therapy: first clinical results. Int J Radiat Oncol Biol Phys 2012; 84 (5): e655–61. 2. Li JS et al. Gains from real-time tracking of prostate motion during external beam radiation therapy. Int J Radiat Oncol Biol Phys 2009; 75 (5): 1613–20.

Schleswig-Holstein (Radiation Oncology), Germany, 3

Illawarra Cancer Care Centre, Wollongong, Australia,

4

University Clinic Schleswig-Holstein (Electrophysiology),

Germany, 5Ingham Institute for Applied Medical Research, Liverpool Hospital, Liverpool, Australia, 6University of Sydney, Sydney, Australia Aim: Atrial fibrillation (AF), the most common cardiac arrhythmia, is affecting >2.5 M Americans and >4.5 M Europeans. AF is usually treated with catheter ablation, a minimally-invasive and timeconsuming technique. Radiosurgery surrounding the pulmonary veins (PV) has been proposed for AF treatment, however the complex respiratory and cardiac motion patterns present a challenge. We hypothesise that an MRI-linac could accomplish the difficult real-time targeting and adaptation tasks. In this study we quantified target motion ranges on cardiac MRI and analysed the dosimetric benefits of margin reduction assuming real-time MRI tracking was applied. Method: Four human subjects underwent real-time cardiac MRI in orthogonal plane orientations under free breathing. The left atrial target motion was analysed with a template matching algorithm on coronal and axial cine planes. The treatment planning study required the definition of an ablation line at each PV antrum as target on an AF patient scheduled for catheter ablation. Different safety margins, ranging from 0 mm (perfect tracking) to 8 mm (untracked motion), were added to define the PTV and 30 Gy single fraction IMRT plans were generated. The influence of a 1T magnetic field on treatment beam delivery was calculated to simulate the impact of MRI guidance on dose distributions. Results: The mean respiratory motion of the target on orthogonal MRI planes was 8.4 mm (SI), 1.7 mm (AP) and 0.3 mm (LR). Cardiac motion was small (100%. The magnetic field had little impact on the dose distribution.

Fig. 1. Results from template matching in the coronal plane. The detected template is outlined in both breathing phases (left: endexhale, right: end-inhale). Conclusion: Our results indicate the feasibility to track the AF targets with real-time MRI. Accurate image guidance for high-dose AF radiosurgery is essential since safety margins covering untracked target motion will result in unacceptable plans.


Oral Abstracts

Thursday 4 September, 1330–1500 Concurrent Session: Chest

29 Educational cases from the thoracic clinic-radiologic MDT (non-lung cancer) F Thien1 and P Naidoo2

Imaging of large and small airway disease P Cronin

1

Eastern Health and Monash University, 2Dandenong

Hospital and Monash Health, Melbourne, Australia

Department of Radiology, Division of Cardiothoracic Radiology, University of Michigan, Ann Arbor, Michigan, United States of America Aim: A variety of inflammatory, infectious, and neoplastic diseases can affect the large airways. Multidetector computed tomography (MDCT) is the diagnostic tool of choice for noninvasive evaluation of the large airways. MDCT can provide both diagnostic information and serve as a guide for planning bronchoscopic interventions. This presentation describes the CT techniques for imaging the large airways, illustrates the CT findings of focal and diffuse tracheobronchial disease, and demonstrates the utility of advanced airway imaging techniques for diagnosis and intervention. Small airways measure ≤2 mm in diameter, are mostly comprised of bronchioles, and are also distinguished by the lack of cartilage and submucosal glands in their walls. This presentation will also review small airway anatomy and the most common small airway diseases, stressing their direct and indirect manifestations on CT imaging including HRCT. The main small airways diseases such as infectious bronchiolitis, panbronchiolitis, follicular bronchiolitis, aspiration bronchiolitis, hypersensitivity pneumonitis (HP), respiratory bronchiolitis (RB), and constrictive bronchiolitis are reviewed with illustrative cases.

Multidisciplinary team (MDT) discussion with clinico-radiological correlation is standard of care in thoracic oncology and has, in recent years, also become central in the diagnosis and management of interstitial lung diseases. The multidisciplinary discussion process integrates complementary clinical perspectives with radiological expertise to aid differential diagnosis and formulation of optimal management plans. This has benefits beyond oncology and interstitial lung disease across the full spectrum of respiratory diseases. The session will use interactive educational cases to demonstrate the multidisciplinary clinicradiological discussion process in focusing radiological differential diagnosis and in optimising clinical management.


30 Pulmonary manifestations of systemic diseases P Cronin Department of Radiology, Division of Cardiothoracic

Oral Abstracts

Thursday 4 September, 1330–1500 Proffered Papers: Radiation Therapy and Oncology: Prostate

Radiology, University of Michigan, Ann Arbor, Michigan, United States of America

Clinical evaluation of a polymer marker for radiotherapy – The POLYGOLD trial

Aim: Many systemic diseases have thoracic manifestations. In some patients the initial presentation of the disease can be abnormality on chest radiograph or chest CT. Only some of the more common diseases are covered in this presentation. The aim of this presentation is to describe the pulmonary manifestations of systemic diseases such as the seropositive arthropaties (rheumatoid disease) and seronegative arthropaties (ankylosing spondylitis), as well as the manifestations of the collagen vascular diseases (systemic lupus erythematosus, scleroderma, polymyositis/dermatomyositis, sjögren syndrome and mixed connective tissue disease). The pulmonary manifestations of the vasculitides (Wegener Granulomatosis and Churg-Strauss Syndrome) are also described. In this presentation, lung diseases such as usual interstitial pneumonia (UIP), non-specific interstitial pneumonia (NSIP), organizing pneumonia and bronchiolitis obliterans which are associated with the collagen vascular diseases are also reviewed. Reference Cronin P. Pulmonary Manifestations of Systemic Diseases in Cardiopulmonary Imaging. Barry H. Gross. Lippincott Williams & Wilkins, 2004.

D Smith,1 D Lim Joon,1 M Wada,1 S Sengupta,2 N Lawrentschuk,2 A Lim1 and V Khoo3 1

Austin Health Radiation Oncology, Melbourne, Victoria,

Australia, 2Austin Health, Department of Urology, Melbourne, Victoria, Australia, 3Department of Clinical Oncology, Royal Marsden NHS Trust, London, United Kingdom Aim: Implanted fiducial markers are regularly used to aide in the safe and accurate delivery of radiotherapy. Image artifact on x-ray imaging may affect identification and delineation of both marker and anatomy. We compare a polymer fiducial marker with respect to visibility and artifact, on x-ray imaging and MRI, to the standard gold marker. Method: A prospective matched cohort study of 14 patients was undertaken following promising results from an earlier phantom study. 14 patients with polymer fiducials inserted into the prostate were matched based on BMI and prostate size to a group of patients with gold fiducials inserted. All patients underwent MRI & CT imaging as part of standard planning procedures, as well as CBCT image verification at treatment. Images were assessed both qualitatively and quantitatively for artifact and visibility. Results: Polymer fiducials produce less artifact on x-ray based imaging than gold and are comparable in their appearance on standard MRI sequences. Insertion was well tolerated and comparable to the ‘standard’ gold group. Conclusion: Polymer fiducial markers provide a potential improvement in radiotherapy target definition and treatment verification over the standard gold.


Oral Abstracts

31

Developing an MRI-based prostate planning method:

High dose rate brachytherapy boost for intermediate

The HIP-MRI project

and high risk prostate cancer: Medium term follow-up

P Pichler,2 J Dowling,1 J Sun,3 D Rivest-Henault,1 S Ghose,1 J Martin, 1

2,3

1

J Fripp, C Wratten

2,3

2,3

and P Greer

Australian E-Health Research Centre, Commonwealth

A Bece,1,2 N Patanjali1 and G Hruby1 1

Chris O’Brien Lifehouse, 2Royal Prince Alfred Hospital,

New South Wales, Australia

Scientific and Industrial Research Organisation, Brisbane, Australia, 2Radiation Oncology, Calvary Mater Hospital, Newcastle, Australia, 3University of Newcastle, Australia Aims: 1. To develop an MRI planning workflow. 2. To determine anatomical and dose variations during radiation therapy of the prostate using weekly MRI scans and MRI-based dose calculations. 3. To investigate deformable image registration (DIR) methods to auto-segment organs and map electron densities. Method: Forty patients had eight planning MRIs during the course of their radiation therapy treatment. A Siemens Skyra 3T MRI scanner with laser bridge and flat couch top was used. Scans included a large field of view (LFOV) T2w pelvis, prostate T2w, T2w gold seed sequence and a T1w flip angle 80 sequence. On these scans, the gold fiducials, bladder, rectum, bones, heads of femur, prostate (CTV) and external (BODY) contours were completed. Scans were uploaded to a CSIRO cloud site. An improved method for creating substitute CT (sCT) scans from whole-pelvic MR scans was developed. Agreement of HU number with the patient CT scan was assessed. Assessment of dose agreement between plans created directly on sCT and the same plan calculated on the CT scan is in progress. Results: The mean absolute error (MAE) in Hounsfield units (HU) between the sCT and patient CT data were 213 ± 114 (mean ± 1 SD) over a HU range from −1000 to 1000. The MAEs are less than 100 HU in the soft-tissue range from −100 to 100 HU. This can be compared to results using a previous average atlas approach of 392 ± 200 HU1. The automatic gold fiducials were identified with 98% accuracy from the T1w small field of view scans when compared to manual contours. Preliminary results show that agreement between sCT and CT isocentre point dose is within 1%. Conclusion: These methods provide the tools for MRI-alone and adaptive prostate radiation therapy. An MRI-only workflow for prostate radiation therapy is feasible, and removes any errors between CT and MRI image registration.

Aim: To report medium term outcomes and toxicities of high dose rate (HDR) brachytherapy boost in the treatment of localised intermediate and high risk prostate cancer. Method: One hundred twenty patients were treated for prostate cancer using HDR brachytherapy boost, followed by external beam radiotherapy (46 Gy in 23 fractions). Between February 2003 and March 2006, 68 patients were treated with a HDR boost of 6.5 Gy × 3 fractions with a single implant; and between May 2006 and October 2008, 52 patients were treated with 2 fractions with separate implants two weeks apart. The dose of the two-fraction brachytherapy course was escalated over that period from an initial 8.5 Gy × 2 (40 patients) to 9.0 Gy × 2 (12 patients). One hundred ten patients received androgen deprivation for 6 months or more. Toxicity was scored using CTCAE 4.0. Results: Our cohort included 81 intermediate and 39 high risk patients. At a median follow up of 6.2 years, 22 patients (18.3%) developed biochemical (N = 14, 11.7%) or clinical (N = 8, 6.7%) recurrence. 7-year actuarial disease-free survival for intermediate and high risk groups was 84.7% and 66.8%, respectively. There have been no local failures to date. 20 patients (16.7%) developed a urethral stricture requiring endoscopic or surgical intervention (grade ≥ 2). Median time to stricture formation was 3.5 years (0.2–7.7 years). The 4- and 7-year cumulative rates of grade 2 or higher urinary toxicity were 12.4% and 21.4%, respectively. Six patients (5%) had grade 2 rectal toxicity. There were no grade 3 rectal toxicities. Conclusion: Treatment of intermediate and high risk prostate cancer with HDR brachytherapy boost shows excellent disease control after 7 years follow up. Toxicities compare favourably with other published series. Urethral strictures continue to develop beyond 5 years, highlighting the importance of long term follow up.

Reference 1. Dowling JA, Lambert J, Parker J, et al. An atlas-based electron density mapping method for magnetic resonance imaging (MRI)alone treatment planning and adaptive MRI-based prostate radiation therapy. International Journal of Radiation Oncology, Biology, Physics 2012 May 1; 83 (1):e5–11.

Fig. 1. Kaplan-Meier disease free survival for intermediate and high risk patients.


32

Oral Abstracts Real-time image-guided adaptive prostate radiotherapy using rectal diameter as a surrogate of motion R Oates,1 A Brown,2 A Tan,2 S Gill,1,3 F Foroudi,1,3 M Lim Joon,1 T Kron,1,3 M Bressel1 and M Schneider4 1

Peter MacCallum Cancer Centre, Melbourne, Victoria,

Australia, 2Townsville Cancer Centre, Townsville, Queensland, Australia, 3Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia, 4Department of Medical Imaging and Radiation Sciences, Monash University, Melbourne, Victoria, Australia

Fig. 2. Cumulative incidence of late urinary toxicity (grade ≥ 2).

Aim: To investigate if a relationship exists between rectal diameter and prostate motion during treatment, with a view to reducing planning target volume (PTV) margins required for an adaptive radiotherapy protocol. Method: In part one of the study 194 post-treatment cone-beam CT (CBCT) images of 10 patients were retrospectively analysed to relate rectum diameter on CBCT to intrafraction prostate displacement. A threshold rectal diameter was used to model the impact of an adaptive PTV margin on rectum and bladder dose during treatment. The potential dose escalation with an adaptive protocol using a 6 mm uniform margin was modelled and compared to our standard PTV margin of 1 cm expansion of the clinical target volume (except 6 mm posterior). Part two of the study will assess 2100 pre-treatment CBCT images of 55 patients using a logistic regression to determine the rectal diameter where the probability of prostate displacements of 4mm or less is at least 0.9. Results: Of 194 fractions, 104 (54%) had a maximum rectal diameter of ≤3.5 cm. Intrafraction prostate displacement was ≤4 mm in 102 of those fractions (98%). The adaptive PTV would have reduced the volume of rectum receiving 25 Gy, 50 Gy, 60 Gy and 70 Gy by 12, 9, 10 and 15% respectively and the volume of bladder by 21, 27, 29 and 35% respectively. The average potential dose escalation with an adaptive protocol was 4.2 Gy while maintaining the rectal dose constraints. Preliminary part two study results indicate that the maximum rectal diameter was ≤3.5 cm in 796 of 1239 fractions (64%) from 33 patients. Conclusion: Our study proposes an improved method of daily adaptive prostate radiotherapy by describing a relationship between prostate motion and the rectal diameter on CBCT. This method may allow implementation of an adaptive margin from the first fraction and offer the potential for reduced treatment toxicity and/or dose escalation.


Oral Abstracts

33

Predicting late urinary toxicity after prostate

Maintaining personal space – A prospective study

radiotherapy: Dosimetric and clinical factors,

evaluating the efficacy of SpaceOAR® hydrogel in

including medication intake

reducing interfraction target motion for patients with

A Yahya,1,2 M Ebert,1,3 M Bulsara,4 A Steigler,5

prostate cancer undergoing radiotherapy

D Joseph1 and J Denham5

L Nguyen, A See and Y Aarons

1

Epworth Healthcare, Victoria, Australia

University of Western Australia, Western Australia, 2

3

Australia, National University of Malaysia, Malaysia, Sir Charles Gairdner Hospital, Western Australia, Australia, 4

University of Notre Dame, Australia, Western Australia,

Australia, 5University of Newcastle, New South Wales, Australia Aim: Knowledge of factors predicting toxicity may help the decision making process for a more tailored treatment and patient care. Using carefully collected RADAR (TROG 03.04) trial data, we aim to explore dosimetric and clinical factors, including medication intake, impacting late urinary toxicity after prostate radiotherapy. Method: Bladder dose-surface histograms (reduced with principal component analysis), data describing clinical factors including medication intakes and late urinary toxicity evaluation for 754 patients accrued during RADAR were available. Urinary toxicity endpoints derived from physician-reported LENT-SOMA and the International Prostate Symptom Score (IPSS) questionnaire were analysed with univariate and multivariate analysis (MVA) with an extended bootstrapping technique. Patients with pre-treatment symptoms were excluded from analysis. Results: In MVA, the impact of acute symptoms were strongest for all endpoints; IPSS5 (increase of ≥5 IPSS points from baseline) (odds ratio (OR):2.78, 95% confidence interval (CI):1.87–4.13, p < 0.001), dysuria (OR:3.21, CI:2.01–5.07,p < 0.001), incontinence (OR:4.84,CI:2.97–7.77,p < 0.001), frequency (OR:2.91, CI:1.96– 4.30,p < 0.001) and haematuria (OR:7.67,CI:2.28–22.81,p < 0.001). Except for incontinence (which did not relate to dosimetric factors), the first principal component (PC1), which was highly correlated to low and intermediate doses, was important. Poorer ECOG performance status affected IPSS5 (OR:1.64,CI:1.01–2.62,p = 0.041) and incontinence (OR:1.70,CI:1.06–5.30,p = 0.025) while pre-treatment bowel condition increased dysuria (OR:2.64,CI:1.43–4.70,p < 0.001) and haematuria (OR:2.31,CI:1.17–4.31,p = 0.008). Non-steroidal anti-inflammatory drugs intake affected dysuria (OR:1.67,CI:0.97–2.82,p = 0.049). Increased age, higher BMI, cerebrovascular condition and smoking significantly increased one endpoint each. Conclusion: Clinical factors predominate in most endpoints, while low and intermediate doses were the most important dosimetric factors. Some significant factors are consistent with previously published results while some other factors have previously rarely been studied requiring further validation to produce accurate predictive tools.

Aim: Through the use of real-time tracking and online imaging, it has been shown that application of an endo-rectal balloon during radiotherapy can reduce intra-fraction prostate motion1. This study evaluated the immobilising effect of a hydrogel spacer in reducing inter-fraction target motion in men throughout a course of radiotherapy for clinically localised prostate cancer. Method: Twenty patients receiving IMRT from 78 to 82 Gy in 2 Gy fractions were enrolled on this prospective, non-randomised study. Ten underwent transperineal implant of three gold marker fiducials into the prostate gland along with SpaceOAR® hydrogel into the retro prostatic space, while the other ten received fiducials alone. The stability of the target was evaluated across 10 kilovoltage Cone Beam CT (CBCT) verification scans by comparing displacement of prostate centroid position relative to (i) hydrogel centroid position (ii) anterior rectal wall (iii) posterior rectal wall and (iv) isocentre position against measurements taken from simulation CT and MRI (T2 weighted) scans. Results: Patient baseline characteristics along with analysis of interfraction target motion of patients with SpaceOAR hydrogel® compared to those without will be presented.

Fig. 1. Axial images from the same patient (a) pre implant CT, (b) post implant CT, (c) post implant MRI (T2 weighted) and (d) pre treatment CBCT. Conclusion: An immobilising effect in patients with SpaceOAR® hydrogel implants was observed. Further analysis quantifying this reduced interfraction motion is required in a larger patient cohort working towards the ultimate goals of margin reduction and dose escalation for prostate cancer. Reference 1. Smeenk RJ, Laouwe RJ, Langen KM, Shah AP, Kupelian PA, van Lin EN et al. An endorectal balloon reduces intrafraction prostate motion during radiotherapy. IJROBP 2012; 83: 661–9.


34

Oral Abstracts

Achieving the best prostate IMRT/VMAT plan – Working towards an individualised approach

Thursday 4 September, 1330–1500 Proffered Papers: Radiobiology

H Caine,1 A Kneebone,1,2 P McCloud,3 T Eade1,2 and D Whalley1 1

The effect of increasing radiation doses on normal and

Northern Sydney Cancer Centre, Royal North Shore

Hospital, New South Wales, Australia, 2University of Sydney, 3

malignant cell migration J Crosbie,1 R Aharon,2 C Lo,3 C Nowell,4 I Mohammed,1

Sydney, New South Wales, Australia, McCloud Consulting

F Klebaner,2 K Hamza2 and P Rogers1

Group, New South Wales, Australia

1

University of Melbourne, Dept of Obstetrics & Gynaecology,

2

School of Mathematics, Monash University, 3Monash

Aim: To retrospectively analyse radiotherapy variables in definitive prostate IMRT/VMAT planning and determine their relationship to plan quality. Method: One hundred and one definitive dose-escalated prostate patients were treated with IMRT or VMAT between October 2012 and January 2014. Patients received 80 Gy in 40 fractions to 95% of the high dose PTV created by a 7 mm uniform CTV expansion except 5 mm posteriorly. Of these patients, 44 received simultaneous pelvic lymph node treatment to 60 Gy. The following structures were used for analysis: prostate PTV and CTV, lymph node treatment (y/n), bladder volume, rectal volume, and overlap of bladder (%OB) and rectum (%OR) within the PTV. Univariate and multivariate linear regression was performed to assess plan quality as defined by bladder and rectal DVH constraints and tumour coverage objectives. Results: All plans achieved PTV D95 = 80 Gy, with no significant relationship between dosimetric coverage and size of prostate or organ at risk volumes. On univariate and multivariate analysis there was a highly significant relationship between the predictors %OR and %OB (p < 0.001) and response variables of 1 cc maximum dose, V40 and V65 of the respective organs. Lymph node irradiation was significantly associated with increasing bladder and rectal V40 and bladder V65 (p < 0.001) but not rectal V65 (p = 0.313 univariate; p = 0.608 multivariate). There were significant linear relationships between bladder volume with V40 and V65, and between rectal volume and V65, but %OR and %OB appeared to be stronger predictors. Thirty-two patients also had rectal spacers (SpaceOAR) which improved all rectal endpoints significantly, although %OR was a stronger variable. Conclusion: We have demonstrated that baseline radiotherapy planning variables can be used to differentiate patients who are less likely to meet DVH constraints. These variables can be combined to create individualised DVH objectives and used to improve plan quality and workflow in the planning process.

Institute of Medical Research, Monash University, 4

Department of Pharmacy, Monash University, Victoria,

Australia Aim: The aim of the project is to investigate how normal and malignant cell migration is influenced by conventional radiotherapy doses as well as by experimental treatments such as microbeam radiation therapy (MRT). Radiation-induced tumour cell migration is a recognised phenomenon that can occur when cells are sub-lethally irradiated. Our group previously demonstrated that tumour cells showed extensive migration 24 hours post-MRT. Method: We irradiated well chamber slides containing cultured normal (L929 mouse fibroblasts) and malignant cells (4T1.2 mouse mammary tumour) with a range of doses (2, 5, 10 Gy) using a conventional, Cobalt- 60 source. The dose range was comparable to the ‘valley’ dose in synchrotron MRT. We used time-lapse microscopy (live cell imaging) and image processing techniques to track individual, fluorescentlylabelled cells within the well chamber slides for up to 48 hrs post-RT. Results: Statistical analysis of the live cell microscopy data for quasiisolated cells showed there was a notable increase in the variance over all cell displacements in the x and y direction at a given time t, when cells were irradiated with doses of 2 Gy or 5 Gy of conventional radiation. We observed; (a) an increase in variation of movement of 4T1.2 cells over time with 0 Gy, likely due to not only cell movement but also asynchronous cell cycling and proliferation, subsequently dampened with increasing dosages of radiation. (b) We noted a bi-phasic response with 5 Gy in both cell lines with the initial ‘hit’ of radiation generating an immediate response which switches over to a longerterm response when the damage finally takes its toll on the cells and they slow down to die. Conclusion: The cells’ migratory capacity was clearly affected or modulated by the conventional radiation doses. This modulation could be important for MRT studies since the low, ‘valley’ dose may leave cells sub-lethally irradiated.


Oral Abstracts

35

Effects of synchrotron microbeam radiotherapy on

Collagen and hypoxia-related gene expression associated

tumour-associated neutrophil and macrophage

with CT texture parameters in non-small cell lung cancer

recruitment in a mouse breast cancer model

A Cormican and K Miles

Y Yang,1 A Swierczak,2 M Ibahim,1 P Paiva,1 A Stevenson,3

Princess Alexandra Hospital, Queensland, Australia

J Crosbie,1 R Anderson2 and P Rogers1 1

University of Melbourne Dept of Obstetrics and 2

Gynaecology, Division of Research Peter MacCallum Cancer Centre, 3The Imaging and Medical Beamline, The Australian Synchrotron, Victoria, Australia Aim: Conventional radiotherapy (CRT) is a routine treatment for up to 50% of breast cancer patients. However, CRT may compromise antitumour responses by triggering inflammatory responses, increasing immune repressive molecules, and recruiting tumour-associated neutrophils (TANs) or macrophages (TAMs) to tumours. Synchrotron Microbeam radiotherapy (MRT) is a novel preclinical RT, in which synchrotron-generated X-rays are segmented by a collimator, producing intense microbeams. Animal studies have demonstrated that MRT ablates tumours but causes little or no damage to the surrounding normal tissues compared to CRT. In this study, we investigated the effects of MRT/CRT on the recruitment of TANs and/or TAMs to tumours.We hypothesised that MRT induces a different immunological response in the tumour microenvironment, which leads to less TAN/ TAM recruitment compared to CRT. Method: Balb/c mice were inoculated with 5 × 105 EMT6.5 mouse mammary tumour cells in the right hind leg. Tumours were irradiated with MRT (112 and 560 Gy peak dose) or CRT (5 and 9 Gy) and excised at 24, 48 and 120 hr post-irradiation. Flow cytometry analysis, quantitative real-time PCR and immunohistochemistry were applied to quantify TAN or TAM recruitment, and production of chemokines/ cytokines responsible for immune cell recruitment. Results: We found that there was a significant difference in both TAN and TAM recruitment in tumours irradiated with MRT and CRT at 48 hr post-irradiation. MRT induced significantly less TAN and TAM recruitment when compared to CRT (p < 0.01). There was less chemokine (C-C motif) ligand 2 (CCl2) expression in tumours irradiated by MRT than CRT, which may be one of the mechanisms responsible for reduced tumour-associated immune cell recruitment. Other mechanisms such as increased macrophage proliferation may also play an important role. Conclusion: Our results suggest that MRT may show advantages over CRT for improving tumour control through its effect on immune cell recruitment to tumours.

Aim: Regional variations in CT attenuation quantified by CT texture analysis (CTTA) have been shown to be prognostic in Non-Small Cell Lung Cancer (NSCLC), and are likely to relate to areas of collagenisation (high attenuation) or necrosis (low attenuation) within tumours.1 This study utilises a publically available image archive with corresponding DNA microarray data to characterise collagen and hypoxia-related gene expression associated with CTTA Parameters in NSCLC.2,3 Method: CTTA comprised the filtration-histogram method applied to the CT component of archived PET-CT images from 26 NSCLC patients. Texture parameters (entropy, standard deviation, kurtosis) for filter values up to 6 mm radius were correlated with the expression of 13 and 8 genes associated with collagenisation and hypoxia respectively. Spearman correlations

Abstracts of the 2014 combined scientific meeting: Imaging and Radiation in Personalised Medicine, 4-7 September, 2014. Melbourne, Australia.

Abstracts of the WFH 2014 World Congress, May 11-15, 2014, Melbourne, Australia.

Abstracts of the ESCP 9th Scientific and Annual Meeting, 24-26 September 2014, Barcelona, Spain.

Abstracts of the Seventh Scientific Meeting of The TMJ Association, 7-9 September 2014, Bethesda, Maryland.

Abstracts of the EAO 23rd Annual Scientific Meeting, September 25-27, 2014, Rome, Italy.

September 2014.

Occupational Therapy Australia, 26th National Conference and Exhibition, 1-3 July 2015, Melbourne Convention and Exhibition Centre.

Continuing medical education: september 2014.

Abstracts of the Australian and New Zealand Society for Geriatric Medicine Annual Scientific Meeting, 28-30 May 2014, Melbourne, VIC, Australia.

Abstracts from the FEBS EMBO 2014 Conference, 30 August-4 September, 2014, Paris, France.

Abstracts from the 2014 ISDE World Congress, September 22-24, 2014, Vancouver, Canada.

The Australasian College of Dermatologists 47th Annual Scientific Meeting, 18-21 May, 2014, Melbourne, Victoria.

Genomic resources notes accepted 1 August 2014-30 September 2014.

Abstracts of the 50th Annual Scientific Meeting of the Australian and New Zealand Society of Nephrology, 25-27 August, 2014, Melbourne, Australia.

Abstracts of the XXXII Annual Scientific Meeting of the British Blood Transfusion Society, 24-26 September 2014, North Yorkshire, UK.

Editor's perspectives--September 2014.

Abstracts from the 12th Annual Scientific Meeting of Medical Imaging and Radiation Therapy, Perth, Australia, 24-26 March 2017.

Multimodality imaging: bird's eye view from The European Society of Cardiology Congress 2014 Barcelona, August 30-September 3, 2014.

Abstracts of the 2014 SGI 61st Annual Scientific Meeting, March 26-29, 2014, Florence Italy.

Abstracts of the 2014 AUGS-IUGA Scientific Meeting, July 22-26, 2014, Washington DC.

Abstracts from the Environmental Mutagenesis and Genomics Society, 45th Annual Meeting, September 13–17, 2014, Orlando, Florida.

IRSSD 2014 Meeting Abstracts.

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