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Quality assurance in radiation therapy: Future plans in physics
Inl. J. Radiation Oncology Biol. Phys., Vol. Printed in the U.S.A. All rights reserved.
IO. Sup.
I, pp. 43-44 Copyright
03M23016/84/$3.00 + .OO @ 1984 Pergamon Press Ltd.
??Session I: U.S. and Canadian Experience
QUALITY
ASSURANCE IN RADIATION THERAPY: FUTURE PLANS IN PHYSICS N.
SUNTHARALINGAM,
Thomas Jefferson University,
PH.D.
Philadelphia,
PA
Modern day radiation therapy has seen the impact of high technology resulting in more sophisticated computer augmented treatment delivery systems, treatment planning procedures and diagnostic imaging techniques. Much work has already been reported in the area of physics efforts related to quality assurance in radiation therapy. Future efforts in physics will have to address the new developments in each component of the whole radiation treatment process. Certain new developments, using both computer and imaging technologies, show promise in providing tools to verify the accuracy of the delivered radiation treatment. Areas receiving careful attention are: integration and registration of information from multiple sources of diagnostic studies; validation of the accuracy of treatment planning systems; assessment of relative merits of alternate dose distributions; improvement of portal and verification film image quality; real time monitoring using light emitting screens and coupled with TV systems; monitoring of treatment and machine parameters using “record and verify” computer systems. The medical physics community, primarily through the American Association of Physicists in Medicine (AAPM), will continue the development of methodologies for technology transfer in the area of quality assurance. Committees and task groups within the AAPM will address the new developments impacting on quality assurance and prepare appropriate protocols and documents to assist the practicing physicist. By necessity, the national Radiological Physics Center (RPC) and the regional Centers for Radiological Physics (CRP) will have to take a major role in the development of new quality assurance programs. Quality assurance in physics.
Treatment Treatment ?? Treatment ?? Treatment
Modern day radiation therapy practices have seen the impact of high technology resulting in more sophisticated computer augmented treatment delivery systems, treatment planning procedures and diagnostic imaging techniques. The state of the art of technologies in imaging devices and displays, computers and their mass storage media, and compact accelerator design have stimulated new initiatives in the planning and delivery of radiation treatments. New approaches to patient management, with emphasis on precision high dose radiation therapy, are already being planned. Quality assurance programs in radiation therapy, especially future efforts in the physical aspects, should address these new developments. Quality assurance programs in radiation therapy need to be comprehensive and should carefully consider each and every step of the process in the management of the cancer patient. The process of radiotherapeutic management, usually can be subdivided into the following: ?? ??
Diagnostic Treatment
Information Simulation
Accepted for publication
?? ??
New procedures have to be established for the assessment of uncertainties in each of the above steps in the whole radiation therapy process and an evaluation made of their impact on the quality of the total care. Even though some work has already been reported in the area of physics efforts related to quality assurance, much more needs to be done. Specific topics that will receive attention in the near future are addressed below.
DIAGNOSTIC INFORMATION AND SIMIJLATION With the availability of different tomographic devices, medical cross-sectional imaging now provides a wealth of useful information to help plan the treatment. Even though several of these studies are of disparate types, attempts are being made to correlate the
gathering
23 November
Planning/Dose Calculation Delivery Verification Outcome/Follow-up
83. 43
44
Radiation
Oncology
0 Biology 0 Physics
geometric spatial information obtained from each of them. This requires studying methods to incorporate all information, getting them into registration, and of cross-referencing data from transverse sectional studies and projection studies. Manual methods of extraction and transfer of spatial data can lead to large uncertainties. Efforts to automate image acquisition with development of computer systems specifically for the purpose of analyzing and synthesizing data from different diagnostic procedures would help minimize the spatial uncertainties in patient data. This area is currently receiving attention from some of the medical centers involved with the delivery of specialized radiation treatments. Image reconstruction and display in arbitrary planes, extraction of projection views from multiple section scans and effectively combining crosssectional imaging and simulation are areas being actively pursued.
TREATMENT
PLANNING/DOSE
CALCULATION
Until recently, computers have been used in radiation therapy primarily for the calculation of radiation dose distributions. Although they are in widespread use it must be recognized that this calculation of dose is performed under rather restricted ideal conditions. Rarely does one encounter dose distributions other than that for the central plane. Early attempts to achieve accurate dose calculations for an irregularly shaped target volume with the radiation beams passing through an inhomogeneous patient were limited by lack of anatomic and tissue density information. Now, however, computerized tomography provides much of the necessary information and improved accuracy in the calculation of dose is possible. However, only approximate methods that account for all the interaction processes and complexities of photon and electron transport in a heterogeneous medium are in current use, because of the practicality of the methods for clinical use. Physical dose distribution, with emphasis on high dose to the target volume while minimizing dose to adjoining critical normal tissues, is an important parameter in the choice of the optimal treatment technique. Unfortunately, no aids currently exist to assist the clinician in assessment of the relative merits of rival treatment plans. This is true of both image presentation and analytic tools. Treatment optimization and methods of scoring different treatment plans are under study. Several commercial treatment planning computer systems are in clinical use. There is a widespread use of a variety of systems without the benefit of a systematic method for exploring the accuracy limitations and comparing results generated by the different systems. In an overall quality assurance program the validation of the accuracy of treatment planning computer systems should be a major undertaking.
1984, Volume
10, Supplement
TREATMENT
1
DELIVERY
AND VERIFICATION
Physics efforts related to quality assurance in radiation therapy have for the most part been directed towards treatment delivery and treatment verification. Quality assurance programs, specific to the type of facility, addressing treatment machine performance have been instituted. Procedures for verification of the actual delivered treatment include beam placement films and in some situations in vivo dosimetry using thermoluminescence dosimeters. Certain new developments, using both computer and imaging technologies, show promise in providing tools to verify the accuracy of the delivered treatment. What was once a simple evaluation of a portal film placed side by side with a simulation film, has now moved to new approaches involving real time monitoring of the target volume using light emitting screens coupled with TV systems. Also, computer augmented “Record and Verify” systems developed primarily for daily monitoring of machine and treatment parameters specific to each patient’s treatment are gaining acceptance. Record and verify systems offer methods for collection of treatment data which will be useful information for any outcome analysis. However, methods need to be developed to monitor the quality and accuracy of the data. TREATMENT
OUTCOME/FOLLOW-UP
The outcome of the delivered treatment necessarily rests on the accuracy with which each step was carried out in the overall radiation therapy process. Since computers are playing an increasingly important role it is now possible to systematically analyze the uncertainties in each process from the large amount of collected data. Computer systems also allow the integration of data that is related to any one patient’s management, diagnosis, planning, treatment and follow-up. It is also possible to have this data available to a national data collection facility for inclusion in any study attempting to establish national benchmarks in the practice of radiation therapy. Again, the quality and accuracy of this data needs to be carefully established. TECHNOLOGY
TRANSFER
The medical physics community in the United States, primarily through the American Association of Physicists in Medicine (AAPM), will continue the development of methodologies for technology transfer in the area of quality assurance. Committees and task groups within the AAPM will address the new developments affecting quality assurance and prepare appropriate protocols and documents to assist the practicing physicist. By necessity, the already successful national Radiological Physics Center (RPC) and the regional Centers for Radiological Physics (CRPs) will have to play a major role in the development and implementation of new quality assurance programs.
IO. Sup.
I, pp. 43-44 Copyright
03M23016/84/$3.00 + .OO @ 1984 Pergamon Press Ltd.
??Session I: U.S. and Canadian Experience
QUALITY
ASSURANCE IN RADIATION THERAPY: FUTURE PLANS IN PHYSICS N.
SUNTHARALINGAM,
Thomas Jefferson University,
PH.D.
Philadelphia,
PA
Modern day radiation therapy has seen the impact of high technology resulting in more sophisticated computer augmented treatment delivery systems, treatment planning procedures and diagnostic imaging techniques. Much work has already been reported in the area of physics efforts related to quality assurance in radiation therapy. Future efforts in physics will have to address the new developments in each component of the whole radiation treatment process. Certain new developments, using both computer and imaging technologies, show promise in providing tools to verify the accuracy of the delivered radiation treatment. Areas receiving careful attention are: integration and registration of information from multiple sources of diagnostic studies; validation of the accuracy of treatment planning systems; assessment of relative merits of alternate dose distributions; improvement of portal and verification film image quality; real time monitoring using light emitting screens and coupled with TV systems; monitoring of treatment and machine parameters using “record and verify” computer systems. The medical physics community, primarily through the American Association of Physicists in Medicine (AAPM), will continue the development of methodologies for technology transfer in the area of quality assurance. Committees and task groups within the AAPM will address the new developments impacting on quality assurance and prepare appropriate protocols and documents to assist the practicing physicist. By necessity, the national Radiological Physics Center (RPC) and the regional Centers for Radiological Physics (CRP) will have to take a major role in the development of new quality assurance programs. Quality assurance in physics.
Treatment Treatment ?? Treatment ?? Treatment
Modern day radiation therapy practices have seen the impact of high technology resulting in more sophisticated computer augmented treatment delivery systems, treatment planning procedures and diagnostic imaging techniques. The state of the art of technologies in imaging devices and displays, computers and their mass storage media, and compact accelerator design have stimulated new initiatives in the planning and delivery of radiation treatments. New approaches to patient management, with emphasis on precision high dose radiation therapy, are already being planned. Quality assurance programs in radiation therapy, especially future efforts in the physical aspects, should address these new developments. Quality assurance programs in radiation therapy need to be comprehensive and should carefully consider each and every step of the process in the management of the cancer patient. The process of radiotherapeutic management, usually can be subdivided into the following: ?? ??
Diagnostic Treatment
Information Simulation
Accepted for publication
?? ??
New procedures have to be established for the assessment of uncertainties in each of the above steps in the whole radiation therapy process and an evaluation made of their impact on the quality of the total care. Even though some work has already been reported in the area of physics efforts related to quality assurance, much more needs to be done. Specific topics that will receive attention in the near future are addressed below.
DIAGNOSTIC INFORMATION AND SIMIJLATION With the availability of different tomographic devices, medical cross-sectional imaging now provides a wealth of useful information to help plan the treatment. Even though several of these studies are of disparate types, attempts are being made to correlate the
gathering
23 November
Planning/Dose Calculation Delivery Verification Outcome/Follow-up
83. 43
44
Radiation
Oncology
0 Biology 0 Physics
geometric spatial information obtained from each of them. This requires studying methods to incorporate all information, getting them into registration, and of cross-referencing data from transverse sectional studies and projection studies. Manual methods of extraction and transfer of spatial data can lead to large uncertainties. Efforts to automate image acquisition with development of computer systems specifically for the purpose of analyzing and synthesizing data from different diagnostic procedures would help minimize the spatial uncertainties in patient data. This area is currently receiving attention from some of the medical centers involved with the delivery of specialized radiation treatments. Image reconstruction and display in arbitrary planes, extraction of projection views from multiple section scans and effectively combining crosssectional imaging and simulation are areas being actively pursued.
TREATMENT
PLANNING/DOSE
CALCULATION
Until recently, computers have been used in radiation therapy primarily for the calculation of radiation dose distributions. Although they are in widespread use it must be recognized that this calculation of dose is performed under rather restricted ideal conditions. Rarely does one encounter dose distributions other than that for the central plane. Early attempts to achieve accurate dose calculations for an irregularly shaped target volume with the radiation beams passing through an inhomogeneous patient were limited by lack of anatomic and tissue density information. Now, however, computerized tomography provides much of the necessary information and improved accuracy in the calculation of dose is possible. However, only approximate methods that account for all the interaction processes and complexities of photon and electron transport in a heterogeneous medium are in current use, because of the practicality of the methods for clinical use. Physical dose distribution, with emphasis on high dose to the target volume while minimizing dose to adjoining critical normal tissues, is an important parameter in the choice of the optimal treatment technique. Unfortunately, no aids currently exist to assist the clinician in assessment of the relative merits of rival treatment plans. This is true of both image presentation and analytic tools. Treatment optimization and methods of scoring different treatment plans are under study. Several commercial treatment planning computer systems are in clinical use. There is a widespread use of a variety of systems without the benefit of a systematic method for exploring the accuracy limitations and comparing results generated by the different systems. In an overall quality assurance program the validation of the accuracy of treatment planning computer systems should be a major undertaking.
1984, Volume
10, Supplement
TREATMENT
1
DELIVERY
AND VERIFICATION
Physics efforts related to quality assurance in radiation therapy have for the most part been directed towards treatment delivery and treatment verification. Quality assurance programs, specific to the type of facility, addressing treatment machine performance have been instituted. Procedures for verification of the actual delivered treatment include beam placement films and in some situations in vivo dosimetry using thermoluminescence dosimeters. Certain new developments, using both computer and imaging technologies, show promise in providing tools to verify the accuracy of the delivered treatment. What was once a simple evaluation of a portal film placed side by side with a simulation film, has now moved to new approaches involving real time monitoring of the target volume using light emitting screens coupled with TV systems. Also, computer augmented “Record and Verify” systems developed primarily for daily monitoring of machine and treatment parameters specific to each patient’s treatment are gaining acceptance. Record and verify systems offer methods for collection of treatment data which will be useful information for any outcome analysis. However, methods need to be developed to monitor the quality and accuracy of the data. TREATMENT
OUTCOME/FOLLOW-UP
The outcome of the delivered treatment necessarily rests on the accuracy with which each step was carried out in the overall radiation therapy process. Since computers are playing an increasingly important role it is now possible to systematically analyze the uncertainties in each process from the large amount of collected data. Computer systems also allow the integration of data that is related to any one patient’s management, diagnosis, planning, treatment and follow-up. It is also possible to have this data available to a national data collection facility for inclusion in any study attempting to establish national benchmarks in the practice of radiation therapy. Again, the quality and accuracy of this data needs to be carefully established. TECHNOLOGY
TRANSFER
The medical physics community in the United States, primarily through the American Association of Physicists in Medicine (AAPM), will continue the development of methodologies for technology transfer in the area of quality assurance. Committees and task groups within the AAPM will address the new developments affecting quality assurance and prepare appropriate protocols and documents to assist the practicing physicist. By necessity, the already successful national Radiological Physics Center (RPC) and the regional Centers for Radiological Physics (CRPs) will have to play a major role in the development and implementation of new quality assurance programs.