Australas Phys Eng Sci Med (2013) 36:387–396 DOI 10.1007/s13246-013-0228-7

ACPSEM ROSG RECOMMENDATION PAPER

ACPSEM brachytherapy working group recommendations for quality assurance in brachytherapy Claire Dempsey • Ryan Smith • Thulani Nyathi Abdurrahman Ceylan • Lisa Howard • Virendra Patel • Ram Das • Annette Haworth

•

Published online: 12 December 2013  Australasian College of Physical Scientists and Engineers in Medicine 2013

Abbreviations AAPM American Association of Physicists in Medicine ACPSEM Australasian College of Physical Scientists and Engineers in Medicine ADCL Accredited Dosimetry Calibration Laboratory ARPANSA Australian Radiation Protection and Nuclear Safety Agency Bq Becquerel, current SI unit of activity (s-1) BTWG Brachytherapy working group CAPCA Canadian Association of Provincial Cancer Agencies Ci Curie, apparent activity (s-1), 1 Bq = 2.70910-11 Ci. Use of this unit is discouraged CT Computed tomography GEC-ESTRO Groupe Europe´en de Curiethe´rapie (GEC) and the European Society for Therapeutic Radiology and Oncology (ESTRO)

Gy HDR HEBD

C. Dempsey (&) Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Waratah, NSW, Australia e-mail: [email protected]

L. Howard Department of Radiation Oncology, St George Hospital, Kogarah, NSW, Australia

C. Dempsey School of Health Sciences, University of Newcastle, Newcastle, NSW, Australia R. Smith William Buckland Radiotherapy Centre, The Alfred Hospital, Melbourne, VIC, Australia T. Nyathi Department of Medical Physics, Waikato Hospital, Hamilton, New Zealand

IAEA IGRT LDR LEBCWG MBDCA MU MR NRL PDR QA ROMP ROSG

Gray, unit of absorbed dose (J/kg) High dose rate AAPM and GEC-ESTRO High-energy Brachytherapy Source Dosimetry working group International Atomic Energy Agency Image-guided radiation therapy Low Dose Rate AAPM Low Energy Brachytherapy Calibration working group Model-based dose calculation algorithms Monitor unit Magnetic resonance National Radiation Laboratory Pulsed dose rate Quality assurance Radiation oncology medical physicist Radiation oncology specialty group

V. Patel Department of Radiation Oncology, Liverpool Hospital, Liverpool, NSW, Australia R. Das Viewbank, VIC, Australia A. Haworth Peter MacCallum Cancer Centre, Melbourne, VIC, Australia A. Haworth University of Melbourne, Melbourne, VIC, Australia

A. Ceylan Department of Radiation Oncology, Wollongong Hospital, Wollongong, NSW, Australia

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388

Sk SSRMP

Sv TEAP TG TPS TRUS

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Air Kerma strength (units are Gy m2 h-1, commonly abbreviated to U) Swiss Society of Radiobiology and Medical Physics Sievert, unit of dose equivalent radiation (J/ kg) ACPSEM Training, Education and Assessment Program Task group Treatment planning system Trans-rectal ultrasound

Foreword The Australasian College of Physical Scientists and Engineers in Medicine (ACPSEM) Radiation Oncology Specialty Group (ROSG) formed a series of working groups in 2011 to develop recommendation papers for guidance of radiation oncology medical physics practice within the Australasian setting. These recommendations are intended to provide guidance for safe work practices and a suitable level of quality control without detailed work instructions. It is the responsibility of the medical physicist to ensure that locally available equipment and procedures are sufficiently sensitive to establish compliance to these recommendations. The recommendations are endorsed by the ROSG, have been subject to independent expert reviews and have also been approved by the ACPSEM Council. For the Australian audience, these recommendations should be read in conjunction with the Tripartite Radiation Oncology Practice Standards [1, 2]. This publication presents the recommendations of the ACPSEM Brachytherapy Working Group (BTWG) and has been developed in alignment with other international associations. However, these recommendations should be read in conjunction with relevant national, state or territory legislation and local requirements, which take precedence over the ACPSEM recommendation papers. It is hoped that the users of this and other ACPSEM recommendation papers will contribute to the development of future versions through the Radiation Oncology Specialty Group of the ACPSEM.

Overview Introduction Brachytherapy is a radiation therapy modality where the discrete radiation source is placed either within or close to the tumour or tissue intended to be irradiated. The inverse

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square law effect in this instance produces a steep dose gradient, allowing for a large amount of dose to be delivered to the intended region whilst sparing surrounding healthy tissue. This modality is different from nuclear medicine procedures since the radionuclide is not involved in body metabolism. There are two implant modalities used in brachytherapy; permanent and temporary implants. Temporary implants, such as those used in high dose rate (HDR) and pulsed-dose rate (PDR) brachytherapy, use multiple or single high activity, high energy photon source(s) such as iridium-192. The source(s) is implanted in the body at predetermined positions (dwell positions) for short periods of time (dwell times). There are also occasions where low dose rate (LDR) sources can be used in temporary implants. Permanent implants typically use LDR, low activity, low energy sources that are implanted into the patient [3] where they remain permanently. This document serves as a guideline for calibration and quality assurance (QA) of equipment and radioactive sealed sources used for brachytherapy in Australasia. It has been designed to supersede the ACPSEM 1997 brachytherapy recommendations [4]. This report does not aim to replace local legislation requirements but rather serve as recommendations for acceptable standards in QA and establish consistency of brachytherapy across the region. The BTWG, however, supports the concept of a riskassessment based approach to QA and recognises that variations in QA practices may occur as a result of local practices, and treatment and QA equipment [5].

Imaging Providing accurate dose delivery to a relatively small target in the presence of a steep dose gradient involves several planning stages. One of the most critical steps is source and catheter localisation. This determines the position and orientation of each source (or source dwell position) relative to the patient anatomy. The traditional and most basic method to achieve this is orthogonal radiographs. However, the target and a complete view of any soft tissue organs at risk are not easily identified on conventional radiographs, making volumetric dose prescribing and optimisation unattainable. CT, MR and ultrasound imaging in applicator insertion and source localisation (planning) processes is commonly used with modern brachytherapy treatments [6, 7]. CT and MR QA programs should be maintained as a fundamental part of any radiation therapy department and is not covered in this document. The ACPSEM BTWG endorse the recommendations of the AAPM TG 128 report (2008) for QA of trans-rectal ultrasound (TRUS) imaging

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equipment, commonly used in prostate HDR and LDR treatments [8]. Radiation sources in general use There are several sources and source types that can be used in a brachytherapy program. These include alpha and beta emitters as well as gamma emitters (both LDR and HDR sources). The medical physicist is responsible for the dosimetry and maintenance of alpha and beta emitters used as sealed sources in ophthalmic applicators. Isotopes typically include yttrium-90, strontium-90 and ruthenium-106 [7]. This type of brachytherapy is not covered in detail in this document. For further information on this form of brachytherapy and related QA issues please refer to AAPM TG 40 [9], AAPM TG 149 [10] and IAEA TecDoc 1274 [11] reports. Gamma emitters are used in both LDR and HDR/PDR form in radiation therapy departments. The common gamma emitters used in Australasia are iodine-125 for LDR, and iridium-192 for HDR/PDR [7]. Other gamma emitters such as caesium-131 and palladium-103 are available for LDR brachytherapy however these are not routinely used in Australasia. Afterloaders Due to the nature of radioactive decay, use of preloaded procedures and the inability to turn a brachytherapy source ‘‘off’’, the radiation risk to medical personnel can be significant in brachytherapy. In order to reduce this risk, afterloading techniques are commonly employed. Afterloading involves positioning of the active source material after the treatment applicator or guide tube has been inserted, verified and accepted by the imaging techniques. In LDR brachytherapy, manual afterloading may be acceptable if completed with appropriate shielding, welltrained staff and safety procedures in accordance with national, state or territory and local regulations. Remote afterloading, in which the source or sources are automatically inserted into the patient under control of staff in remote position, is the preferred method for LDR and is obligatory for PDR and HDR brachytherapy [9, 12]. LDR remote afterloading units are no longer used in Australia and New Zealand and are not covered in this document. For more information please refer to the AAPM TG 41 report [13]. Physical quantities and source calibration in brachytherapy At the time of writing, the universally accepted method for specification of brachytherapy source strength is the air

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kerma strength (Sk) at a defined distance in air [14, 15]. European standards laboratories are currently working on the development of a dose to water standard and it is expected that this standard will replace the air kerma standard in the next few years [16]. Presently, source calibration certificates may state source strength in terms of apparent activity. Care must be taken to use the same air kerma rate constant used by the vendor to convert this value to air kerma rate before it is used clinically. Australian and New Zealand standard dosimetry laboratories do not maintain primary Sk standards for commonly used brachytherapy sources and therefore the following is recommended for source strength specification: a)

Common to all sources • At the centre where the patient is to be treated, a qualified medical physicist is responsible for the calibration of each brachytherapy source or an accepted number from each batch of sources [17]. • The AAPM Task Group 56 [6] report provides an update on the recommendations of AAPM Task Group 40 [9] report. The ACPSEM BTWG endorses the updated recommendations, which state that all departments shall have a system to complete source strength measurements that have equipment calibration traceable to a standards laboratory for all source types being used for brachytherapy treatments in its practice. The vendor supplied source strength should no longer be used as the sole method for source strength specification. • The ACPSEM BTWG recommends the measured source strength should be used for source strength specification in the brachytherapy treatment unit; however, this recommendation is based on the assumption that the source strength is measured with appropriately calibrated and maintained measurement equipment and by appropriately trained personnel. If the measured source strength is outside the stated tolerances specified in Tables 1 and 2, a calibration should be done by another physicist or with another calibrator and if this measurement also is outside the stated accuracy, the source should not be used clinically. • A suitably calibrated well-type ionisation chamber is the preferred method for calibration of brachytherapy sources. Appropriate well chambers are described in the IAEA TecDoc 1274 (Sect. 7) [11]. These chambers have demonstrated long-term stability and shall be calibrated at an accredited standards laboratory for the same source design used in the local hospital. The uncertainty of the measurement device for the primary method of measurement of source strength shall be \2 %. If the well chamber is to be

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390 Table 1 Quality assurance tests for HDR/PDR brachytherapy

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Test Description

Performance Tolerance

Reference Action

Pre-treatment (Daily) Door interlock / last person out

Functional

A40, C1, E, N, S

Treatment interrupt

Functional

A40, C1, E, N, S

Emergency off (console)

Functional

A40, C1, E, N, S

Room radiation monitor

Functional

A40,C1, E, N, S

Console displays (treatment status indicator, date, time, source strength)

Functional

A40, C1, E, N, S

Printer operation, paper supply Data transfer from planning computer

Functional Functional

A40, C1, E, N, S A40, C1, E, N, S

Audio/ visual communication system

Functional

Source positional accuracy

1 mm

2 mm

A40, C1, E, N, S

Dwell time accuracy

1%

2%

C1

Timer termination

Functional

Accuracy of source and dummy loading

1 mm

Controlled area signs: posted and/ or illuminated

Positive

Emergency equipment (bail out pig, pliers)

Positive

Applicator clamp

Positive

Applicator interlocks: simulate interlocks Monitor patient post-treatment to ensure radiation source has been removed At source replacement (Quarterly)

A40, C1, E, N, S

E 2 mm

A40

Functional Complete

Mechanical integrity of applicators, guide tubes, connectors

Functional

A40, C1, E, N, S

Emergency off (in room)

Functional

A40, C1, E, N, S

Power failure recovery

Functional

Source strength calibration

3%

A40, C1, E, N, S 5%

C1, E, N, S

Source positional accuracy

1 mm

2 mm

A40, C1

Dwell time accuracy

1%

2%

A40, C1

Timer linearity

1%

2%

Records

Complete

C1

Obstructed catheter

Functional

E

Stability of the local standard Leakage radiation

2% 10 lSvhr-1

S

Applicator too long or too short

1 mm

Check contents of emergency equipment (bail out pig, pliers) and make available during source change

Complete

Communication of source movements with manufacturer

Complete

C1

S 2 mm

A40, S

Annually

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Hand held monitor

Functional

E

Hand crank functioning

Functional

E

Transit dose reproducibility

1%

2%

C1

X-ray marker positional accuracy

1 mm

2 mm

A40, C1, S

Review emergency response procedures

Complete

C1

Independent quality control review

Complete

C1

Irradiation timer Leakage radiation

1% 10 lSvhr-1

[1 %

E, N S

Length of treatment tubes

1 mm

[1 mm

E

Quality assurance manual review/update

Complete

Implant reconstruction

1 mm

2 mm

N

Australas Phys Eng Sci Med (2013) 36:387–396 Table 1 continued

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Test Description

Performance Tolerance

Applicator dimensions/ damage

Reference Action

Visual Inspection

Applicator and catheter attachment

Functional

Contamination test

\200 Bq or 5 nCi

Review usage and clinical practice in consideration of shielding requirements

Complete

I

ADCL calibration Precision

Biennial 2%

A40, A56 A40, A56

Linearity

1%

A40, A56

Collection efficiency

1%

A40, A56

Redundant check

2%

A40, A56

ADCL calibration

Biennial

A40, A56

Accuracy of source chamber distance

1%

A40, A56

Before each use constancy check

5%

A40, A56

Dosimeter/Chamber QA Well-Ionisation Chamber

A40 AAPM TG 40 [9]/ ACPSEM [4], A56 AAPM TG 56 [6],.C1 CAPCA 1 [33], E ESTRO [34], N NETHERLANDS and BELGIUM [35], S SWITZERLAND SSRMP [36], I IPEM Report 81[7]

Thimble Chamber (In Air Jig)

Annual chamber constancy

2%

A40, A56

Monthly energy response

3%

A40, A56

used as the primary method of defining the source strength for the treatment unit then the chamber shall undergo regular QA checks as defined in Table IV of AAPM report from Task Group 56 [6]. The well chamber shall be calibrated at an accredited standards laboratory at an interval of no more than 2 years and, following calibration, the issued calibration factor shall be confirmed through independent methods, which may include a constancy check with a longlived source such as Cs-137. b)

LDR sources •

The ACPSEM BTWG endorse the recommendations of the AAPM Low Energy Brachytherapy Calibration Working Group (LEBCWG) [17] with minor modifications. The reader is referred to this publication for the justification of the number of sources to assay, and the action and tolerance levels. The number of seeds to assay depends on the number of seeds within a batch with the same strength grouping and is summarised as follows: – –

–

When the number of sources in a strength group is \10, all sources should be assayed. For non-sterile loose sources, an assay of C10 % of the total sources or 10 sources, whichever is larger. For cartridges, C10 % of the total sources is to be assayed. This can be completed using a whole cartridge assay or via single sources. When

–

–

–

possible, random samples from the cartridge are preferred. For purchases of sterile assemblies (pre-loaded patient kits), additional non-sterile loose seeds from the same batch can be ordered for assay. The assay should include at least five sources for each patient order. For purchases of sterile assemblies only, an assay of C10 % of assemblies or C10 % of the total sources should be measured using a sterile well chamber insert or quantitative image analysis. For sterile strands, the assay should include C10 % of the total sources if measured using a sterile well chamber insert, however, for a typical implant containing less than 150 seeds, an additional, non-sterile strand containing ten seeds from the same batch is sufficient for assay. If additional sources are ordered for the purpose of calibration, it must be noted that not all seed manufacturers guarantee that additional sources supplied will be from the same manufacturing batch. Action and tolerance levels for the mean value of the measured source strength for a multi-seed implant are summarised in Table 2. For further details regarding actions to be taken when tolerances are exceeded, or for implants with small numbers of sources refer to Butler et al [17].Use of pre-loaded needle services for LDR prostate brachytherapy is now common practice

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392 Table 2 Quality assurance tests for LDR prostate* brachytherapy

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Test Description

Performance Tolerance

Reference Action

Pre-and post-treatment (Daily) Radiation monitor

Functional

Source strength verification (well chamber)

3%

US system/ probe

Functional

A56, A64, C2, E, I 5%

A40, A56, A64, C2, E, I A64, C2, E

Source inventory

Complete

A56, C2, E, I

Records

Complete

A56, C2, E, I

Source calibration, mean of batch

3%

B, E

Source calibration, individual source

5%

B, E

Source identification

Positive/ radiograph

A40, E

Physical/chemical form (at initial receipt only)

Document

A40

Source encapsulation (at initial receipt only)

Document

A40

Calibrator (e.g. well chamber leakage)

Document

A40

Documentation on receipt of seeds

Complete

A56, I

Leak test confirmation

Complete

I

Calibrator (e.g. well chamber) constancy

2%

Autoradiograph

Complete

I

Check for damage on receipt of seeds

Complete

A56

Console displays (treatment status indicator, date, time, source strength)

Functional

C2, E

Printer operation, paper supply

Functional

C2, E

System self-test

Functional

C2, E

Delivery interrupt

Functional

C2, E

Power failure recovery

Functional

C2, E

Data transfer from planning computer

Functional

C2, E

Seed loading devices

Functional

C2, E

Communication between all systems

Functional

C2, E

Emergency seed loading kit (if applicable)

Functional/ Sterilized

C2

5%

A40, I

Planning and seed loading devices

Online source strength verification.

8%

Radiation survey

Complete

15%

A56, A64, I

C2

Source inventory

Complete

I

Grid calibration in US system

Complete

Well-chamber calibration

1%

Calibrator (e.g. well chamber) energy response

3%

Quarterly E 2%

C2 I

Annually Ultrasound positional accuracy

1 mm

2 mm

Ultrasound volumetric accuracy

5%

10%

C2

1 mm

2 mm

C2

Template positional accuracy

1 mm

2 mm

C2

Source parameters and TPS dose calculation verification

2%

3%

C2

Stepper positional accuracy

123

C2

Australas Phys Eng Sci Med (2013) 36:387–396 Table 2 continued

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Test Description

Performance Tolerance

* Note a subset of these tests is applicable for non-prostate LDR implants with a smaller number of seeds. For these applications the reader is referred to Butler et al [17] for specific recommendations on source assay tolerances and sample sizes A40 AAPM TG 40 [9]/ ACPSEM [4], A56 AAPM TG 56 [6], A64 AAPM TG 64 [38], A128 AAPM TG 128 [8], B Butler et al [17], C2 CAPCA 2 [39], E ESTRO [34], I IPEM Report 81 [37]

Action

Emergency seed handling procedures review.

Complete

Independent quality control review.

Complete

A64, C, I

Grayscale visibility

[2 steps or 10%

A128

Depth of penetration

[1 cm

A128

Axial and lateral resolution

[1 mm

A128

Axial distance measurement accuracy

[2 mm or 2%

A128

Lateral distance measurement accuracy

[3 mm or 3%

A128

Area measurement accuracy

[5%

A128

Volume measurement accuracy

[5%

A128

Needle template alignment

[3 mm

A128

[5%

A128

TPS volume accuracy Planning and seed loading devices

C2

Online source strength measurements device calibration/ verification

3%

5%

C2, I

Source positional accuracy (loading devices)

2 mm

3 mm

C2

in Australasia. In addition to taking responsibility for the assay of the sources as previously described, the institutional medical physicist (responsible for patient care at the centre where the patient is to be treated) is responsible for verifying the needle loading pattern prior to implantation. c)

Reference

HDR and PDR sources • In addition to the primary measurement of the source strength, a secondary measurement method should be made available as confirmatory check of source strength and to assist in the resolution of discrepancies between the primary measurement method and the certified value. The preferred method uses an ion chamber calibrated at an Australian or New Zealand standards laboratory and free-in-air jig as described by Butler et al [18]. Alternatively, a Farmer chamber, along with a hospital supplied air-jig can be calibrated according the IPEM Code of Practice at the National Physical Laboratory (IPEM COP) [16] and used for measurements. A secondary well chamber and electrometer (not used with the primary method of source strength measurement) may also be used as the secondary check method. The secondary measurement method shall be capable of detecting errors within a 5 % uncertainty.

The working group identified that the only method of calibrating the HDR/PDR source traceable to an Australian or New Zealand dosimetry standard is an ion chamber calibrated according to the interpolation method of Goetsch [19] and following the free-in-air calibration

procedure of IAEA TecDoc 1274 [11]. The working group acknowledged that this method requires careful measurement of source strength and use of correction factors that may not be accurately known, possibly leading to an unacceptable uncertainty in source strength. The working group therefore recommend that if the source Sk cannot be determined at the local site with equipment traceable to an Australian or New Zealand dosimetry standard within a 3 % confidence/acceptable accuracy, then the value stated on the source calibration certificate may be accepted on condition it is at least verified by direct measurement using a well chamber. Treatment planning In brachytherapy, the fundamental requirement of a treatment planning system is that the reference data used by the planning system is appropriate for the source type that will be used for treatment delivery. Source data for a single isotope can vary by source manufacture as a result of variations in geometry and encapsulation. At the time of writing, the universal calculation algorithm used in brachytherapy treatment planning systems is based on the AAPM TG 43 formalism, which uses look-up tables to calculate point doses and 3D dose distributions [14, 15]. AAPM TG 43 (2004) report provides consensus data sets for commercially available brachytherapy sources and provides recommendations for selection of appropriate data for newly developed sources [15]. In 2012, the AAPM and GEC-ESTRO high-energy brachytherapy source dosimetry (HEBD) working group provided updated datasets for high-energy brachytherapy source dosimetry parameters and guidelines for characterization methods for high-

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energy brachytherapy sources [20]. It is recommended that this publication is used in conjunction with AAPM TG 43 [5] when validating the source information within the treatment planning system. In HDR/PDR brachytherapy, it is recommended that an independent treatment time calculation should be performed to verify that the selected absolute absorbed dose distribution is at least approximately consistent with the specified arrangement, source positions, strength and dwell times [7]. There are a limited number of commercial checking programs available and if a department is without such a program then the reader is referred to the AAPM TG 59 report (Sect. 4) for a verification methodology [12]. In LDR permanent implant brachytherapy, ‘postimplant’ dosimetric analysis must occur in order to determine the radiation dose delivered due to the actual configuration of sources as they remain in-situ. These data may be used to confirm an adequate dose has been delivered to the patient and can provide a means of QA for future patient procedures [21, 22].

introduction has already commenced [29, 30]. Commissioning and QA of such models will require in-depth analysis and more rigorous dosimetric verification. The AAPM TG 186 in collaboration with GEC-ESTRO and the Australasian Brachytherapy Group have published a guidance document for early adopters of MBDCAs [29] and are currently developing benchmarking data sets to assist the commissioning process. A change in the customary dose prescription may result from this in the future, leading away from intuitive treatment plan checking. Until consensus documents are published, early adopters of this algorithm are cautioned against making changes to current prescribing methods and to remain using those based on the TG-43 formalism. New treatment applicators are continually being released, requiring new dose interpretation and optimization methods. In LDR prostate brachytherapy, the range of sources available is expected to increase and their use should be restricted to the research environment until dosimetry data is published according to the recommendations of TG-43 [15].

Safety and legislative requirements

User training

Most incidents involving radiotherapy sources are due to procedural errors [23]. The QA tests listed in this document for brachytherapy are primarily focussed on addressing radiation safety issues for the patient, staff and general public. These include the reference documents from which they arise and deal with radiation source specification, treatment unit QA, treatment planning quality control and general radiation safety protocols. Within Australasia, both ARPANSA (in Australia) and the NRL (in New Zealand) have legislation regarding the transport, handling and security of radioactive sources [24–27] which is based on the IAEA international codes of conduct for the safety and security of radioactive sources [28]. Each department must ensure they comply with these requirements as part of a brachytherapy QA program. Handling and storage of dislodged radioactive seeds in LDR permanent implants shall be in accordance with national, state or territory and local regulations. Adequate information shall be provided to the patient so that they may comply with the safety protocol. The ARPANSA document 14.3 (Sect. 9.2) states the patient should be provided a means of retrieval and storage of dislodged sources and they should be returned to the radiation safety officer of the treatment institution as soon as possible [26].

Radiation therapy involves complex systems, processes and procedures involving staff from many disciplines. Formal training programs such as the ACPSEM training, education and assessment program (TEAP) are designed to equip Radiation Oncology Medical Physicists (ROMPs) with the skills and knowledge to carry out acceptance, commissioning and QA tests described in these recommendations and the experience to identify procedural or equipment errors. Brachytherapy is a specialised radiation therapy treatment modality. Treatments commonly require large doses of radiation be delivered within a short time frame between applicator insertion and treatment delivery. As a minimum, expertise should include the anatomy being treated, concepts of brachytherapy treatment planning, dose prescription methods and calculation and operation of the treatment delivery system where required. All staff attending HDR treatments should be trained in and regularly practice emergency procedures.

Future direction Model-based dose calculation algorithms (MBDCAs) are currently under development and limited commercial

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Acceptance tests, clinical commissioning and quality assurance Acceptance testing involves subjecting newly received equipment to exhaustive performance testing to confirm compliance with both the vendor’s technical and the institution’s clinical specifications. Commissioning requires collecting physical and dosimetric data as needed

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for clinical implementation of the system and establishing baselines for future reference measurements. This applies to all apparatus associated with the treatment service and may include treatment units, treatment planning systems, imaging units, patient devices and associated QA and dosimetry equipment. Vulnerable decision points in these processes, where human error or device failure could cause discrepancies in dose delivery, should be identified and appropriate redundant checks designed in a QA program. The purpose of the QA program is to ensure that all devices required for treatment planning and delivery continue to function within defined tolerance levels. These tolerance levels shall be set to realistically reflect the capabilities of the equipment and achieve clinically acceptable levels of treatment accuracy. This program often consists of a subset of commissioning tests, which are to be performed at fixed intervals [31]. All acceptance tests, commissioning measurements and QA tests are derived from international published recommendations and author experience where published references are lacking. The equipment used in the QA program shall be regularly maintained and calibrated at regular intervals as specified in Tables 1 and 2.

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It is also recommended that there are clearly defined categories for evaluation of radiotherapy equipment performance that should be addressed when implementing a QA program [32]. i. ii. iii. iv. v. vi.

Operation. Accuracy. Reproducibility. Characterisation and correction. Data transfer and validation. Completeness.

Quality assurance The ACPSEM BTWG recommendations for HDR/PDR and LDR QA are listed in Tables 1 and 2. These recommendations consist of tests to be performed, along with their minimum frequency. Frequencies Pre-treatment (Daily): Quarterly (or on source replacement):

Tolerances and action levels Annually: For quantities that can be measured, both tolerance and action levels may be defined in this recommendation paper [6]. 1.

2.

Tolerance Level. Tolerance levels will take into account measurement uncertainties and the performance capabilities of the equipment. It is preferable that all measurements are within tolerance levels. Action Level. If a measurement lies between the tolerance and action levels, there are several options available. Corrective action should be taken immediately if the problem is quickly and easily resolved, otherwise it may be delayed until the next maintenance period or until the performance of the failed parameter is confirmed. In latter instances, the behaviour of the component in question must be closely monitored. In all instances, users of this equipment must be informed of the issue and the action taken. A wider deviation from a benchmark or baseline, called the action level, triggers mandatory action. All users of this equipment must be informed and the system is removed from clinical use until it is functioning within tolerance levels or at the very least the equipment must be constrained to clinical situations in which the failed component is not used.

Once during every treatment day and separated by at least 24 h On average once every 3 months and/or after each source replacement On average once every 12 months and at intervals of between 10 and 14 months

Acknowledgments The authors would like to acknowledge the work done by the chair of the ACPSEM ROSG, Michael Bailey, for implementation of the concept of the position papers and organisation of the Radiation Oncology working parties.

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