Editorial
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Image-guided intraoperative radiation therapy: current developments and future perspectives Expert Rev. Med. Devices 11(5), 431–434 (2014)
Javier Pascau Departamento de Bioingenierı´a e Ingenierı´a Aeroespacial, Universidad Carlos III de Madrid, Avda. de la Universidad, 30, 28911 Legane´s, Madrid, Spain and Instituto de Investigacio´n Sanitaria Gregorio Maran˜o´n, Calle Doctor Esquerdo, 46, 28007 Madrid, Spain [email protected]
Intraoperative electron beam radiation therapy (IOERT) procedures involve the delivery of radiation to a target area during surgery by means of a specific applicator. This treatment is currently planned by means of specific systems that incorporate tools for both surgical simulation and radiation dose distribution estimation. Although the planning step improves treatment quality and facilitates follow-up, the actual position of the patient, the applicator and other tools during the surgical procedure is unknown. Image-guided navigation technologies could be introduced in IOERT treatments, but an innovative solution that overcomes the limitations of these systems in complex surgical scenarios is needed. A recent publication describes a multi-camera optical tracking system integrated in IOERT workflow. This technology has shown appropriate accuracy in phantom experiments, and could also be of interest in other surgical interventions, where the restrictions solved by this system are also present.
Intraoperative electron beam radiation therapy (IOERT) refers to the precise delivery of high-dose electron beam radiation at the time of an operation to the target area (residual tumor or tumor bed) limiting the exposure of surrounding tissues [1]. This direct identification and visualization of the target area is one of the main advantages of IOERT [2,3]. Soft x-rays is an alternative to IOERT that is also clinically available. Both techniques are widely applied in breast cancer [4] and the equivalence to conventional radiotherapy treatment has been recently evaluated in Electron Intra Operative Radiation Therapy [5] and Targeted Intraoperative Radiotherapy trials [6]. Several institutions carry out IOERT procedures in different locations and, according to a recent European study [7], the most frequently treated tumor sites are breast and rectal cancer, followed by sarcoma, prostate and pancreatic cancer. The lack of more randomized clinical trials due to the complexity of IOERT is frequently presented as a limitation of this technique.
Treatment planning in IOERT
External beam radiation therapy (EBRT) treatments are planned with specific systems where several parameters such as patient’s position and anatomy relative to the radiation source, number of treatment fields, collimator shape and beam energy are selected. This choice has a double objective: deliver the prescribed dose to the target area and limit the risk of irradiating the surrounding healthy tissues. IOERT procedures follow the same purpose, but until recently, no treatment planning systems had been available to perform the task in advance. The main difference between EBRT and IOERT is that, in the case of EBRT, the radiation beam is generated outside the patient, whereas in IOERT, it is delivered using an applicator. This specific collimator has a cylindrical shape with different bevel angles available at the end close to the patient and is positioned directly over the target area after surgical exposure. Therefore, IOERT planning needs to incorporate tools for
KEYWORDS: intraoperative radiation • IOERT • IORT • radiotherapy • surgical navigation • tracking system
informahealthcare.com
10.1586/17434440.2014.929494
Ó 2014 Informa UK Ltd
ISSN 1743-4440
431
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Editorial
Pascau
both surgical simulation and radiation dose distribution estimation. The complexity of the required approach had limited the availability of such IOERT planning systems until recently [8]. The current solution facilitates the simulation of applicator positioning by means of a preoperative CT scan of the patient and an interactive 3D visualization. Estimated dose delivered to target areas or organs at risk is also obtained. These advances may improve IOERT treatment quality because of several reasons: the procedures can be evaluated and simulated in advance by the radiation oncologist together with the surgeon, improving their preparation for the intervention; different treatment alternatives can be tested in advance without the temporal constraints that will exist during surgery; finally, both the preoperative planning and the modifications introduced during the real treatment can be adequately documented, enabling detailed follow-up of these patients with improved knowledge about the treatment details. Beyond treatment planning: surgical navigation
Although all these developments have improved the protocols for IOERT, it is also clear that there is one important area that remains unsolved with the solution presented [8]: accurate reporting of both the real patient’s anatomy and the final position details of all treatment elements. The physicians may have simulated the IOERT procedure in advance, but how do they know if the real treatment matches the preoperative simulation? This question applies not only to IOERT, but also to many surgical interventions where combining information from the patient and positions of surgical devices with imaging offers the surgeons a new tool that is called surgical navigation. Several interventions currently benefit from the concept of surgical navigation. Neurosurgery was a pioneering procedure [9]. The neurosurgeons obtain preoperative MRI of the patient with specific landmarks that are later used during surgery to correlate the real positions of the patient or the surgical devices with respect to the MRI. Other example of navigation facilitating interventions is computed tomography or MRI image fusion with real-time ultrasound for radiofrequency ablation of liver lesions [10]. Computed tomography or MRI is acquired before the intervention because the lesions can be localized easily in this kind of study, while ultrasound is obtained during the intervention in order to find the lesions to be ablated with the radiofrequency needle. A navigation system integrates both computed tomography/MR and ultrasound and all studies displayed are synchronized on the screen, improving the user’s ability to localize the targets. Surgical navigation depends on tracking systems to obtain real-world coordinates of the surgical tools, imaging devices or even the patient’s anatomy. These devices can be of two different types: optical tracking systems (OTSs) use cameras to obtain the pose of reference landmarks; electromagnetic tracking systems localize small sensors in an electromagnetic field of known geometry [9]. The main advantages of OTS are their high accuracy and reliability and, although their main limitation is the required line-of-sight between the object to be 432
tracked and the cameras, they are widely used in clinical applications. The main advantage of electromagnetic tracking system is the ability to track objects even inside the human body, but the distortion that metallic objects can cause in the magnetic field used for positioning limits its applications to environments where this factor can be controlled. Navigation in IOERT: new solutions
IOERTs are complex procedures where several medical specialties are involved: surgeons, radiation oncologists, medical physicists, anesthesiologists, nurses and technicians. This means that during an IOERT treatment, it is very difficult to control the environment and, consequently, the line-of-sight limitation of OTS becomes an issue that can completely limit the feasibility of OTS for IOERT navigation. On the other hand, electromagnetic tracking systems do not seem to be an alternative since the surgical theater is not a metal-free environment at all. Consequently, if surgical navigation technologies are to be introduced in IOERT treatments, then an innovative solution is needed. The line-of-sight limitation of current OTS comes from the fact that it is necessary that the positioning landmarks to be tracked are visible by the two cameras used. But if a complex surgical scenario cannot ensure that the direct line between the cameras and the landmarks is always free of occlusions, then the solution may lie in having more cameras trying to watch the object to be tracked. If several cameras surround the tracking volume, then the system will be redundant and robust to occlusions since, in theory, only two cameras are needed to position the objects in the scene. A typical application of this kind of technology is motion capture during filmmaking. The use of these multi-camera systems in medical applications could limit the occlusion problems during intervention and, at the same time, improve the tracking volume, since the cameras could surround the whole surgical bed. The idea of a multi-camera OTS for IOERT treatments has been presented for the first time [11]. This system combines multiple infrared cameras (eight in this case, although this number could be improved depending on the requirements) surrounding the working volume and permanently positioned in the room ceiling to avoid any interference with the surgical procedures. The proposed workflow is the following: • Radiopaque landmarks are placed on patient’s skin; • A preoperative computed tomography of the patient is acquired with the subject’s anatomy situated according to the expected position during surgery; • In the surgical room, the multi-camera optical tracking system is used to obtain real landmark positions that are aligned with the ones displayed in the computed tomography. This registration results in a patient-to-image transformation that can be applied to any object in the real scenario in order to display it over the preoperative data; • The IOERT applicator is tracked in the real scenario and displayed over the preoperative CT scan, so the position and orientation can be assessed with respect to prescribed treatment plan and dose distribution can be calculated. Expert Rev. Med. Devices 11(5), (2014)
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Image-guided intraoperative radiation therapy
This workflow was evaluated in a phantom study in which the applicator’s position and orientation, as provided by the tracking system, were compared with the ones obtained from a computed tomography image used as a gold standard. Three IOERT scenarios were simulated (breast, upper abdomen and pelvis) with average accuracy around 1.8 mm in position and 1.6˚ in orientation. These figures include the whole end-to-end experiment with sources of error such as calibration of the optical tools, intrinsic optical system limitations and point-to-point registration with user interaction. These measurements are small compared with the diameter of the IOERT applicator and within the acceptable range proposed in the TG-147 recommendation (Therapy Committee and the Quality Assurance and Outcomes Improvement Subcommittee of the American Association of Physicists in Medicine [12]). Future directions
Multi-camera tracking systems can facilitate the introduction of image-guided navigation in complex surgical scenarios and IOERT with electron beams is a good example of those. In the near future, IOERT procedures would include not only accurate dose distribution planning, but also intraoperative imaging. The navigation workflow proposed [11], combined with a computed tomography study acquired during surgery using a mobile device [13], would provide all the information necessary at the time of surgery to replicate the quality assurance available in EBRT. It could seem that the availability of intraoperative computed tomography decreases the value of the tracking system but, even in that future scenario, the ability to preview the impact of the current applicator position in terms of delivered dose would be of interest. If the intraoperative image is acquired with the applicator already in place, then no tracking system is needed, but this position could not be modified. If the applicator position is obtained from the tracking system and displayed on computed tomography, then different alternatives can be evaluated and the best one selected. Other areas of interest include the treatment follow-up, taking advantage of the information present in preoperative,
1.
2.
3.
Calvo FA, Meirino RM, Orecchia R. Intraoperative radiation therapy first part: rationale and techniques. Crit Rev Oncol Hematol 2006;59(2):106-15 Kusters M, Valentini V, Calvo FA, et al. Results of European pooled analysis of IORT-containing multimodality treatment for locally advanced rectal cancer: adjuvant chemotherapy prevents local recurrence rather than distant metastases. Ann Oncol 2010;21(6):1279-84 Valentini V, Calvo F, Reni M, et al. Intra-operative radiotherapy (IORT) in pancreatic cancer: joint analysis of the
informahealthcare.com
intraoperative (if available) or postoperative images. If these studies were available, registration techniques could facilitate the integration of dose information even with other radiation therapy treatments. Boost procedures in which IOERT is combined with EBRT would benefit from the summation of treatment plans. A detailed evaluation of the anatomy changes from preoperative to intraoperative environment with specific recommendations depending on the different locations would also be an interesting study. For some locations, preoperative information could be enough to plan the treatment, while intraoperative update may be absolutely necessary in others. The existing experience shows some limitations in real environments, but the promising results have encouraged the ongoing preliminary clinical experiences. Accordingly [14], the system that is best placed to have an impact on clinical outcome will offer not only accurate registration and tracking, but also seamless integration within the standard operating room and no interference with the traditional clinical workflow. The multi-camera OTS complies with some of these desired features in a truly challenging clinical task as IOERT. This approach could also be of interest in other complex surgical interventions where the restrictions solved by this system are also present. Financial & competing interests disclosure
JA Santos-Miranda, FA Calvo, V Garcı´a-Va´zquez, E Marinetto, C Illana, M Fabio-Valdivieso, I Balsa and M Desco are part of the team involved in the development of new solutions for image-guided IOERT. This work was partially supported in Spain by Ministerio de Economı´a y Competitividad (PI-11/02908, IPT-300000–2010–3, IPT-2012–0401–300000, TEC2010–21619-C04–01), Comunidad de Madrid (ARTEMIS S2009/DPI-1802) and ERD funds. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript. for local control and overall survival from the TARGIT-A randomised trial. Lancet 2014;383(9917):603-13
ISIORT-Europe experience. Radiother Oncol 2009;91(1):54-9
References 4.
5.
6.
Editorial
Kalakota K, Small W Jr. Intraoperative radiation therapy techniques and options for breast cancer. Expert Rev Med Devices 2014;11(3):265-73 Veronesi U, Orecchia R, Maisonneuve P, et al. Intraoperative radiotherapy versus external radiotherapy for early breast cancer (ELIOT): a randomised controlled equivalence trial. Lancet Oncol 2013; 14(13):1269-77 Vaidya JS, Wenz F, Bulsara M, et al. Risk-adapted targeted intraoperative radiotherapy versus whole-breast radiotherapy for breast cancer: 5-year results
7.
Krengli M, Calvo FA, Sedlmayer F, et al. Clinical and technical characteristics of intraoperative radiotherapy. Analysis of the ISIORT-Europe database. Strahlenther Onkol 2013;189(9):729-37
8.
Pascau J, Santos Miranda JA, Calvo FA, et al. An innovative tool for intraoperative electron beam radiotherapy simulation and planning: description and initial evaluation by radiation oncologists. Int J Radiat Oncol Biol Phys 2012;83(2): e287-95
433
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Editorial
Pascau
9.
Peters TM. Image-guidance for surgical procedures. Phys Med Biol 2006;51(14): R505-40
10.
Lee JY, Choi BI, Chung YE, et al. Clinical value of CT/MR-US fusion imaging for radiofrequency ablation of hepatic nodules. Eur J Radiol 2012;81(9):2281-9
11.
Garcia-Vazquez V, Marinetto E, Santos-Miranda JA, et al. Feasibility of integrating a multi-camera optical tracking system in intra-operative electron radiation
434
therapy scenarios. Phys Med Biol 2013; 58(24):8769-82 12.
Willoughby T, Lehmann J, Bencomo JA, et al. Quality assurance for nonradiographic radiotherapy localization and positioning systems: report of Task Group 147. Med Phys 2012;39(4):1728-47
13.
Siewerdsen JH. Cone-beam CT with a flat-panel detector: from image science to image-guided surgery. Nucl Instrum Methods Phys Res A 2011;648(S1):S241-50
14.
Linte CA, Davenport KP, Cleary K, et al. On mixed reality environments for minimally invasive therapy guidance: systems architecture, successes and challenges in their implementation from laboratory to clinic. Comput Med Imaging Graph 2013;37(2):83-97
Expert Rev. Med. Devices 11(5), (2014)
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Image-guided intraoperative radiation therapy: current developments and future perspectives Expert Rev. Med. Devices 11(5), 431–434 (2014)
Javier Pascau Departamento de Bioingenierı´a e Ingenierı´a Aeroespacial, Universidad Carlos III de Madrid, Avda. de la Universidad, 30, 28911 Legane´s, Madrid, Spain and Instituto de Investigacio´n Sanitaria Gregorio Maran˜o´n, Calle Doctor Esquerdo, 46, 28007 Madrid, Spain [email protected]
Intraoperative electron beam radiation therapy (IOERT) procedures involve the delivery of radiation to a target area during surgery by means of a specific applicator. This treatment is currently planned by means of specific systems that incorporate tools for both surgical simulation and radiation dose distribution estimation. Although the planning step improves treatment quality and facilitates follow-up, the actual position of the patient, the applicator and other tools during the surgical procedure is unknown. Image-guided navigation technologies could be introduced in IOERT treatments, but an innovative solution that overcomes the limitations of these systems in complex surgical scenarios is needed. A recent publication describes a multi-camera optical tracking system integrated in IOERT workflow. This technology has shown appropriate accuracy in phantom experiments, and could also be of interest in other surgical interventions, where the restrictions solved by this system are also present.
Intraoperative electron beam radiation therapy (IOERT) refers to the precise delivery of high-dose electron beam radiation at the time of an operation to the target area (residual tumor or tumor bed) limiting the exposure of surrounding tissues [1]. This direct identification and visualization of the target area is one of the main advantages of IOERT [2,3]. Soft x-rays is an alternative to IOERT that is also clinically available. Both techniques are widely applied in breast cancer [4] and the equivalence to conventional radiotherapy treatment has been recently evaluated in Electron Intra Operative Radiation Therapy [5] and Targeted Intraoperative Radiotherapy trials [6]. Several institutions carry out IOERT procedures in different locations and, according to a recent European study [7], the most frequently treated tumor sites are breast and rectal cancer, followed by sarcoma, prostate and pancreatic cancer. The lack of more randomized clinical trials due to the complexity of IOERT is frequently presented as a limitation of this technique.
Treatment planning in IOERT
External beam radiation therapy (EBRT) treatments are planned with specific systems where several parameters such as patient’s position and anatomy relative to the radiation source, number of treatment fields, collimator shape and beam energy are selected. This choice has a double objective: deliver the prescribed dose to the target area and limit the risk of irradiating the surrounding healthy tissues. IOERT procedures follow the same purpose, but until recently, no treatment planning systems had been available to perform the task in advance. The main difference between EBRT and IOERT is that, in the case of EBRT, the radiation beam is generated outside the patient, whereas in IOERT, it is delivered using an applicator. This specific collimator has a cylindrical shape with different bevel angles available at the end close to the patient and is positioned directly over the target area after surgical exposure. Therefore, IOERT planning needs to incorporate tools for
KEYWORDS: intraoperative radiation • IOERT • IORT • radiotherapy • surgical navigation • tracking system
informahealthcare.com
10.1586/17434440.2014.929494
Ó 2014 Informa UK Ltd
ISSN 1743-4440
431
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Editorial
Pascau
both surgical simulation and radiation dose distribution estimation. The complexity of the required approach had limited the availability of such IOERT planning systems until recently [8]. The current solution facilitates the simulation of applicator positioning by means of a preoperative CT scan of the patient and an interactive 3D visualization. Estimated dose delivered to target areas or organs at risk is also obtained. These advances may improve IOERT treatment quality because of several reasons: the procedures can be evaluated and simulated in advance by the radiation oncologist together with the surgeon, improving their preparation for the intervention; different treatment alternatives can be tested in advance without the temporal constraints that will exist during surgery; finally, both the preoperative planning and the modifications introduced during the real treatment can be adequately documented, enabling detailed follow-up of these patients with improved knowledge about the treatment details. Beyond treatment planning: surgical navigation
Although all these developments have improved the protocols for IOERT, it is also clear that there is one important area that remains unsolved with the solution presented [8]: accurate reporting of both the real patient’s anatomy and the final position details of all treatment elements. The physicians may have simulated the IOERT procedure in advance, but how do they know if the real treatment matches the preoperative simulation? This question applies not only to IOERT, but also to many surgical interventions where combining information from the patient and positions of surgical devices with imaging offers the surgeons a new tool that is called surgical navigation. Several interventions currently benefit from the concept of surgical navigation. Neurosurgery was a pioneering procedure [9]. The neurosurgeons obtain preoperative MRI of the patient with specific landmarks that are later used during surgery to correlate the real positions of the patient or the surgical devices with respect to the MRI. Other example of navigation facilitating interventions is computed tomography or MRI image fusion with real-time ultrasound for radiofrequency ablation of liver lesions [10]. Computed tomography or MRI is acquired before the intervention because the lesions can be localized easily in this kind of study, while ultrasound is obtained during the intervention in order to find the lesions to be ablated with the radiofrequency needle. A navigation system integrates both computed tomography/MR and ultrasound and all studies displayed are synchronized on the screen, improving the user’s ability to localize the targets. Surgical navigation depends on tracking systems to obtain real-world coordinates of the surgical tools, imaging devices or even the patient’s anatomy. These devices can be of two different types: optical tracking systems (OTSs) use cameras to obtain the pose of reference landmarks; electromagnetic tracking systems localize small sensors in an electromagnetic field of known geometry [9]. The main advantages of OTS are their high accuracy and reliability and, although their main limitation is the required line-of-sight between the object to be 432
tracked and the cameras, they are widely used in clinical applications. The main advantage of electromagnetic tracking system is the ability to track objects even inside the human body, but the distortion that metallic objects can cause in the magnetic field used for positioning limits its applications to environments where this factor can be controlled. Navigation in IOERT: new solutions
IOERTs are complex procedures where several medical specialties are involved: surgeons, radiation oncologists, medical physicists, anesthesiologists, nurses and technicians. This means that during an IOERT treatment, it is very difficult to control the environment and, consequently, the line-of-sight limitation of OTS becomes an issue that can completely limit the feasibility of OTS for IOERT navigation. On the other hand, electromagnetic tracking systems do not seem to be an alternative since the surgical theater is not a metal-free environment at all. Consequently, if surgical navigation technologies are to be introduced in IOERT treatments, then an innovative solution is needed. The line-of-sight limitation of current OTS comes from the fact that it is necessary that the positioning landmarks to be tracked are visible by the two cameras used. But if a complex surgical scenario cannot ensure that the direct line between the cameras and the landmarks is always free of occlusions, then the solution may lie in having more cameras trying to watch the object to be tracked. If several cameras surround the tracking volume, then the system will be redundant and robust to occlusions since, in theory, only two cameras are needed to position the objects in the scene. A typical application of this kind of technology is motion capture during filmmaking. The use of these multi-camera systems in medical applications could limit the occlusion problems during intervention and, at the same time, improve the tracking volume, since the cameras could surround the whole surgical bed. The idea of a multi-camera OTS for IOERT treatments has been presented for the first time [11]. This system combines multiple infrared cameras (eight in this case, although this number could be improved depending on the requirements) surrounding the working volume and permanently positioned in the room ceiling to avoid any interference with the surgical procedures. The proposed workflow is the following: • Radiopaque landmarks are placed on patient’s skin; • A preoperative computed tomography of the patient is acquired with the subject’s anatomy situated according to the expected position during surgery; • In the surgical room, the multi-camera optical tracking system is used to obtain real landmark positions that are aligned with the ones displayed in the computed tomography. This registration results in a patient-to-image transformation that can be applied to any object in the real scenario in order to display it over the preoperative data; • The IOERT applicator is tracked in the real scenario and displayed over the preoperative CT scan, so the position and orientation can be assessed with respect to prescribed treatment plan and dose distribution can be calculated. Expert Rev. Med. Devices 11(5), (2014)
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Image-guided intraoperative radiation therapy
This workflow was evaluated in a phantom study in which the applicator’s position and orientation, as provided by the tracking system, were compared with the ones obtained from a computed tomography image used as a gold standard. Three IOERT scenarios were simulated (breast, upper abdomen and pelvis) with average accuracy around 1.8 mm in position and 1.6˚ in orientation. These figures include the whole end-to-end experiment with sources of error such as calibration of the optical tools, intrinsic optical system limitations and point-to-point registration with user interaction. These measurements are small compared with the diameter of the IOERT applicator and within the acceptable range proposed in the TG-147 recommendation (Therapy Committee and the Quality Assurance and Outcomes Improvement Subcommittee of the American Association of Physicists in Medicine [12]). Future directions
Multi-camera tracking systems can facilitate the introduction of image-guided navigation in complex surgical scenarios and IOERT with electron beams is a good example of those. In the near future, IOERT procedures would include not only accurate dose distribution planning, but also intraoperative imaging. The navigation workflow proposed [11], combined with a computed tomography study acquired during surgery using a mobile device [13], would provide all the information necessary at the time of surgery to replicate the quality assurance available in EBRT. It could seem that the availability of intraoperative computed tomography decreases the value of the tracking system but, even in that future scenario, the ability to preview the impact of the current applicator position in terms of delivered dose would be of interest. If the intraoperative image is acquired with the applicator already in place, then no tracking system is needed, but this position could not be modified. If the applicator position is obtained from the tracking system and displayed on computed tomography, then different alternatives can be evaluated and the best one selected. Other areas of interest include the treatment follow-up, taking advantage of the information present in preoperative,
1.
2.
3.
Calvo FA, Meirino RM, Orecchia R. Intraoperative radiation therapy first part: rationale and techniques. Crit Rev Oncol Hematol 2006;59(2):106-15 Kusters M, Valentini V, Calvo FA, et al. Results of European pooled analysis of IORT-containing multimodality treatment for locally advanced rectal cancer: adjuvant chemotherapy prevents local recurrence rather than distant metastases. Ann Oncol 2010;21(6):1279-84 Valentini V, Calvo F, Reni M, et al. Intra-operative radiotherapy (IORT) in pancreatic cancer: joint analysis of the
informahealthcare.com
intraoperative (if available) or postoperative images. If these studies were available, registration techniques could facilitate the integration of dose information even with other radiation therapy treatments. Boost procedures in which IOERT is combined with EBRT would benefit from the summation of treatment plans. A detailed evaluation of the anatomy changes from preoperative to intraoperative environment with specific recommendations depending on the different locations would also be an interesting study. For some locations, preoperative information could be enough to plan the treatment, while intraoperative update may be absolutely necessary in others. The existing experience shows some limitations in real environments, but the promising results have encouraged the ongoing preliminary clinical experiences. Accordingly [14], the system that is best placed to have an impact on clinical outcome will offer not only accurate registration and tracking, but also seamless integration within the standard operating room and no interference with the traditional clinical workflow. The multi-camera OTS complies with some of these desired features in a truly challenging clinical task as IOERT. This approach could also be of interest in other complex surgical interventions where the restrictions solved by this system are also present. Financial & competing interests disclosure
JA Santos-Miranda, FA Calvo, V Garcı´a-Va´zquez, E Marinetto, C Illana, M Fabio-Valdivieso, I Balsa and M Desco are part of the team involved in the development of new solutions for image-guided IOERT. This work was partially supported in Spain by Ministerio de Economı´a y Competitividad (PI-11/02908, IPT-300000–2010–3, IPT-2012–0401–300000, TEC2010–21619-C04–01), Comunidad de Madrid (ARTEMIS S2009/DPI-1802) and ERD funds. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript. for local control and overall survival from the TARGIT-A randomised trial. Lancet 2014;383(9917):603-13
ISIORT-Europe experience. Radiother Oncol 2009;91(1):54-9
References 4.
5.
6.
Editorial
Kalakota K, Small W Jr. Intraoperative radiation therapy techniques and options for breast cancer. Expert Rev Med Devices 2014;11(3):265-73 Veronesi U, Orecchia R, Maisonneuve P, et al. Intraoperative radiotherapy versus external radiotherapy for early breast cancer (ELIOT): a randomised controlled equivalence trial. Lancet Oncol 2013; 14(13):1269-77 Vaidya JS, Wenz F, Bulsara M, et al. Risk-adapted targeted intraoperative radiotherapy versus whole-breast radiotherapy for breast cancer: 5-year results
7.
Krengli M, Calvo FA, Sedlmayer F, et al. Clinical and technical characteristics of intraoperative radiotherapy. Analysis of the ISIORT-Europe database. Strahlenther Onkol 2013;189(9):729-37
8.
Pascau J, Santos Miranda JA, Calvo FA, et al. An innovative tool for intraoperative electron beam radiotherapy simulation and planning: description and initial evaluation by radiation oncologists. Int J Radiat Oncol Biol Phys 2012;83(2): e287-95
433
Expert Review of Medical Devices Downloaded from informahealthcare.com by Chinese University of Hong Kong on 02/07/15 For personal use only.
Editorial
Pascau
9.
Peters TM. Image-guidance for surgical procedures. Phys Med Biol 2006;51(14): R505-40
10.
Lee JY, Choi BI, Chung YE, et al. Clinical value of CT/MR-US fusion imaging for radiofrequency ablation of hepatic nodules. Eur J Radiol 2012;81(9):2281-9
11.
Garcia-Vazquez V, Marinetto E, Santos-Miranda JA, et al. Feasibility of integrating a multi-camera optical tracking system in intra-operative electron radiation
434
therapy scenarios. Phys Med Biol 2013; 58(24):8769-82 12.
Willoughby T, Lehmann J, Bencomo JA, et al. Quality assurance for nonradiographic radiotherapy localization and positioning systems: report of Task Group 147. Med Phys 2012;39(4):1728-47
13.
Siewerdsen JH. Cone-beam CT with a flat-panel detector: from image science to image-guided surgery. Nucl Instrum Methods Phys Res A 2011;648(S1):S241-50
14.
Linte CA, Davenport KP, Cleary K, et al. On mixed reality environments for minimally invasive therapy guidance: systems architecture, successes and challenges in their implementation from laboratory to clinic. Comput Med Imaging Graph 2013;37(2):83-97
Expert Rev. Med. Devices 11(5), (2014)
