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2243 A multi-professional software tool for radiation therapy treatment verification
Proceedings of the 38th Annual ASTRO Meeting
395
2241 CANCELLED 2242 3D-CONFORMAL ANNEALING 1~. Elizabeth Departments
PROSTATE Sands, M.D.,
RADIOTHERAPY:
2John Antolak,
of lRadiotherapy,
Ph.D.,
and 2Radiation
MINIMIZING l~lan
Pollack,
THE
RECTAL
DOSE
BY CONSTRAINED
M.D., Ph.D., 1Gunar K. Zagars, M.D.,
Physics, The University
of Texas, M.D. Anderson
Cancer
SIMULATED
2Isaac I. Rosen, Ph.D Center, Houston,
Texas.
Purpose/Objective: Nearly 200 Stage Tl-3 prostate cancer patients have been entered in a Phase III randomized study comparing conventional (70 Gy) to conformal (78 Gy) radiotherapy. The first 46 Gy in both treatment arms was delivered using a 4-field box nonconformally. Hence, the 3D-conformal treatment was limited to the boost. The purpose of the present study was to determine if the percentage of the rectum receiving 60 Gy and above in the conformal boost arm could be lowered using different boost beam arrangements while maintaining 78 Gy to the isocenter. Constrained simulated annealing was used to evaluate the potential of each boost beam arrangement to achieve this goal. Materials & Methods: The CT-scan contours of twenty patients who had received a conformal 6-field boost were used for this analysis. The prostate, seminal vesicles, rectum, bladder, and femoral heads had previously been delineated on each CT-scan slice. The resultant standard plans for the conformal boosts included a planning target volume (PTV) of 0.75 cm posteriorly and 1.00 - 1.25 cm anteriorly around the gross and clinical tumor volumes (GTV=CTV); the CTV was the prostate and seminal vesicles. Because of the difficulty in reproducing uneven margins for the simulated annealing techniques, the boost PTV was set at 0.8 cm for the generation of auto-shaped standard plans and DVHs for comparison with the other plans. We sought to minimize the rectal volume receiving 60 Gy or more using four different methods: 1) Optimized weights of the standard six boost beams at 60.90, 120,240, 270, and 300 degrees (6 optimized weights). 2) Optimized weights of 36 beams spaced at every 10 degrees (36 optimized weights). 3) Optimized weights and angles for the standard 6 beams using a range of 57-63, 87-93, 117-123, 237-243, 267 273, and 297-303 degrees (optimized angles). 4) Optimized weights with wedges using the standard 6 beam angles; a combination of open and 60 degree wedged beams in each wedge orientation was used (optimized wedges). Constrained simulated annealing is a computer technique which through a reiterative process finds the optimal solution of a given problem. Five thousand iterations were run for the 6-beam auto-shaped optimized boost and ten thousand iterations were run for the other methods. Ideal dose-volume limits were based on an experience with over 100 standard conformal plans: bladder 0% >85 Gy; 20% 270 Gy, 30% 260 Gy; rectum 0% >85 Gy; 20% 270 Gy, 35% &I Gy; and femoral heads 0% >55 Gy, 5% 250 Gy, 25% >45 Gy. Results: The volume of rectum receiving 60 Gy or more was reduced over the auto-shaped standard plan by an average of 2.0% using 6 optimized weights, 2.1% using 36 beam optimized weights, 2.5% using optimized angles, and 6.9% using optimized wedges, These reductions in the rectal volume receiving 60 Gy or more. were statistically significant at p c 0.01. The wedged plan offered a modest reduction in the rectal dose at the expense of dose homogeneity across the PTV. Conclusion: Although each different boost beam arrangement examined offered a statistically significant reduction in the rectal volume receiving Z60 Gy, none was clinically useful. The data indicate that the proportion of the rectum receiving 260 Gy can only be minimally reduced without sacrificing dose homogeneity in the PTV by the tested boost beam arrangements as compared to our current standard 6. beam boost.
2243 A MULTI-PROFESSIONAL Tim Fox, Ph.D.. Ken Brooks, Department
SOFTWARE
TOOL
FOR RADIATION
THERAPY
TREATMENT
VERIFICATION
Ph.D., and Larry Davis, M.D
of Radiation Oncology,
Emory
University
School of Medicine,
Atlanta, Georgia
Purpose: Verification of patient setup is important in conforrnal therapy because it provides a means of quality assurance Electronic portal imaging systems have led to software tools for performing digital comparison and verification of patient software tools are typically designed from a radiation oncologist’s perspective even though treatment verification is oncologists, physicists, and therapists. A new software tool, Treatment Verification Tool (TVT), has been developed professional application for reviewing and verifying treatment plan setup using conventional personal computers. This approach to electronic treatment verification and demonstrate the features of TVT.
for treatment delivery. setup. However, these a team effort involving as an interactive, multistudy will describe our
TVT is an object-oriented software tool written in C++ using the PC-based Windows NT environment. The software Methods and Materials: utilizes the selection of a patient’s images from a database. The software is also developed as a single window interface to reduce the amount of windows presented to the user. However, the user can select thorn four different possible views of the patient data. One of the views is side-byside comparison of portal images (on-line portal images or digitized port film) with a prescription image [digitized simulator film or digitally reconstructed radiograph), and another view is a textual summary of the grades of each portal image. The grades of a portal image are assigned by a radiation oncologist using an evaluation method, and the physicists and therapists may only review these results. All users of TVT can perform image enhancement processes, measure distances, and perform semi-automated registration methods. An electronic dialogue can be established through a set of annotations and notes among the radiation oncologists and the technical staff. Results: Features of TVT include: 1) side-by-side comparison of portal images and a prescription image; 2) image contrast enhancement including histogram equalization; 3) zoomed display of images; 4) communication of evaluation results; 5) remote access of patient data from typical phone connections; and 6) conventional PC-based hardware and software with multiple printer support. Conclusion: TVT is a cost-effective software tool for the comparison of prescription and portal images. It also establishes an electronic dialogue for the communication of the portal image evaluation results. The patient database may also be accessed remotely using a standard PC with a modem and the TVT software. Our department is beginning to use TVT for electronic chart rounds and routine comparisons of portal and prescription images. Future developments are focused on both enabling e mail of text and images and the use of on-line voice comments with each image.
395
2241 CANCELLED 2242 3D-CONFORMAL ANNEALING 1~. Elizabeth Departments
PROSTATE Sands, M.D.,
RADIOTHERAPY:
2John Antolak,
of lRadiotherapy,
Ph.D.,
and 2Radiation
MINIMIZING l~lan
Pollack,
THE
RECTAL
DOSE
BY CONSTRAINED
M.D., Ph.D., 1Gunar K. Zagars, M.D.,
Physics, The University
of Texas, M.D. Anderson
Cancer
SIMULATED
2Isaac I. Rosen, Ph.D Center, Houston,
Texas.
Purpose/Objective: Nearly 200 Stage Tl-3 prostate cancer patients have been entered in a Phase III randomized study comparing conventional (70 Gy) to conformal (78 Gy) radiotherapy. The first 46 Gy in both treatment arms was delivered using a 4-field box nonconformally. Hence, the 3D-conformal treatment was limited to the boost. The purpose of the present study was to determine if the percentage of the rectum receiving 60 Gy and above in the conformal boost arm could be lowered using different boost beam arrangements while maintaining 78 Gy to the isocenter. Constrained simulated annealing was used to evaluate the potential of each boost beam arrangement to achieve this goal. Materials & Methods: The CT-scan contours of twenty patients who had received a conformal 6-field boost were used for this analysis. The prostate, seminal vesicles, rectum, bladder, and femoral heads had previously been delineated on each CT-scan slice. The resultant standard plans for the conformal boosts included a planning target volume (PTV) of 0.75 cm posteriorly and 1.00 - 1.25 cm anteriorly around the gross and clinical tumor volumes (GTV=CTV); the CTV was the prostate and seminal vesicles. Because of the difficulty in reproducing uneven margins for the simulated annealing techniques, the boost PTV was set at 0.8 cm for the generation of auto-shaped standard plans and DVHs for comparison with the other plans. We sought to minimize the rectal volume receiving 60 Gy or more using four different methods: 1) Optimized weights of the standard six boost beams at 60.90, 120,240, 270, and 300 degrees (6 optimized weights). 2) Optimized weights of 36 beams spaced at every 10 degrees (36 optimized weights). 3) Optimized weights and angles for the standard 6 beams using a range of 57-63, 87-93, 117-123, 237-243, 267 273, and 297-303 degrees (optimized angles). 4) Optimized weights with wedges using the standard 6 beam angles; a combination of open and 60 degree wedged beams in each wedge orientation was used (optimized wedges). Constrained simulated annealing is a computer technique which through a reiterative process finds the optimal solution of a given problem. Five thousand iterations were run for the 6-beam auto-shaped optimized boost and ten thousand iterations were run for the other methods. Ideal dose-volume limits were based on an experience with over 100 standard conformal plans: bladder 0% >85 Gy; 20% 270 Gy, 30% 260 Gy; rectum 0% >85 Gy; 20% 270 Gy, 35% &I Gy; and femoral heads 0% >55 Gy, 5% 250 Gy, 25% >45 Gy. Results: The volume of rectum receiving 60 Gy or more was reduced over the auto-shaped standard plan by an average of 2.0% using 6 optimized weights, 2.1% using 36 beam optimized weights, 2.5% using optimized angles, and 6.9% using optimized wedges, These reductions in the rectal volume receiving 60 Gy or more. were statistically significant at p c 0.01. The wedged plan offered a modest reduction in the rectal dose at the expense of dose homogeneity across the PTV. Conclusion: Although each different boost beam arrangement examined offered a statistically significant reduction in the rectal volume receiving Z60 Gy, none was clinically useful. The data indicate that the proportion of the rectum receiving 260 Gy can only be minimally reduced without sacrificing dose homogeneity in the PTV by the tested boost beam arrangements as compared to our current standard 6. beam boost.
2243 A MULTI-PROFESSIONAL Tim Fox, Ph.D.. Ken Brooks, Department
SOFTWARE
TOOL
FOR RADIATION
THERAPY
TREATMENT
VERIFICATION
Ph.D., and Larry Davis, M.D
of Radiation Oncology,
Emory
University
School of Medicine,
Atlanta, Georgia
Purpose: Verification of patient setup is important in conforrnal therapy because it provides a means of quality assurance Electronic portal imaging systems have led to software tools for performing digital comparison and verification of patient software tools are typically designed from a radiation oncologist’s perspective even though treatment verification is oncologists, physicists, and therapists. A new software tool, Treatment Verification Tool (TVT), has been developed professional application for reviewing and verifying treatment plan setup using conventional personal computers. This approach to electronic treatment verification and demonstrate the features of TVT.
for treatment delivery. setup. However, these a team effort involving as an interactive, multistudy will describe our
TVT is an object-oriented software tool written in C++ using the PC-based Windows NT environment. The software Methods and Materials: utilizes the selection of a patient’s images from a database. The software is also developed as a single window interface to reduce the amount of windows presented to the user. However, the user can select thorn four different possible views of the patient data. One of the views is side-byside comparison of portal images (on-line portal images or digitized port film) with a prescription image [digitized simulator film or digitally reconstructed radiograph), and another view is a textual summary of the grades of each portal image. The grades of a portal image are assigned by a radiation oncologist using an evaluation method, and the physicists and therapists may only review these results. All users of TVT can perform image enhancement processes, measure distances, and perform semi-automated registration methods. An electronic dialogue can be established through a set of annotations and notes among the radiation oncologists and the technical staff. Results: Features of TVT include: 1) side-by-side comparison of portal images and a prescription image; 2) image contrast enhancement including histogram equalization; 3) zoomed display of images; 4) communication of evaluation results; 5) remote access of patient data from typical phone connections; and 6) conventional PC-based hardware and software with multiple printer support. Conclusion: TVT is a cost-effective software tool for the comparison of prescription and portal images. It also establishes an electronic dialogue for the communication of the portal image evaluation results. The patient database may also be accessed remotely using a standard PC with a modem and the TVT software. Our department is beginning to use TVT for electronic chart rounds and routine comparisons of portal and prescription images. Future developments are focused on both enabling e mail of text and images and the use of on-line voice comments with each image.