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Comparison of patient-specific intensity modulated radiation therapy quality assurance for the prostate across multiple institutions
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Abstract
Aim
To evaluate the success of a patient-specific intensity modulated radiation therapy (IMRT) quality assurance (QA) practice for prostate cancer patients across multiple institutions using a questionnaire survey.
Background
The IMRT QA practice involves different methods of dose distribution verification and analysis at different institutions.
Materials and Methods
Two full-arc volumetric modulated arc therapy (VMAT) plan and 7 fixed-gantry IMRT plan with DMLC were used for patient specific QA across 22 institutions. The same computed tomography image and structure set were used for all plans. Each institution recalculated the dose distribution with fixed monitor units and without any modification. Single-point dose measurement with a cylindrical ionization chamber and dose distribution verification with a multi-detector or radiochromic film were performed, according to the QA process at each institution.
Results
Twenty-two institutions performed the patient-specific IMRT QA verifications. With a single-point dose measurement at the isocenter, the average difference between the calculated and measured doses was 0.5 ± 1.9%. For the comparison of dose distributions, 18 institutions used a two or three-dimensional array detector, while the others used Gafchromic film. In the γ test with dose difference/distance-to-agreement criteria of 3%−3 mm and 2%−2 mm with a 30% dose threshold, the median gamma pass rates were 99.3% (range: 41.7%–100.0%) and 96.4% (range: 29.4%–100.0%), respectively.
Conclusion
This survey was an informative trial to understand the verification status of patient-specific IMRT QA measurements for prostate cancer. In most institutions, the point dose measurement and dose distribution differences met the desired criteria.
Abstract
Aim
To evaluate the success of a patient-specific intensity modulated radiation therapy (IMRT) quality assurance (QA) practice for prostate cancer patients across multiple institutions using a questionnaire survey.
Background
The IMRT QA practice involves different methods of dose distribution verification and analysis at different institutions.
Materials and Methods
Two full-arc volumetric modulated arc therapy (VMAT) plan and 7 fixed-gantry IMRT plan with DMLC were used for patient specific QA across 22 institutions. The same computed tomography image and structure set were used for all plans. Each institution recalculated the dose distribution with fixed monitor units and without any modification. Single-point dose measurement with a cylindrical ionization chamber and dose distribution verification with a multi-detector or radiochromic film were performed, according to the QA process at each institution.
Results
Twenty-two institutions performed the patient-specific IMRT QA verifications. With a single-point dose measurement at the isocenter, the average difference between the calculated and measured doses was 0.5 ± 1.9%. For the comparison of dose distributions, 18 institutions used a two or three-dimensional array detector, while the others used Gafchromic film. In the γ test with dose difference/distance-to-agreement criteria of 3%−3 mm and 2%−2 mm with a 30% dose threshold, the median gamma pass rates were 99.3% (range: 41.7%–100.0%) and 96.4% (range: 29.4%–100.0%), respectively.
Conclusion
This survey was an informative trial to understand the verification status of patient-specific IMRT QA measurements for prostate cancer. In most institutions, the point dose measurement and dose distribution differences met the desired criteria.
Keywords
Patient-specific IMRT QA; Consistency; VMAT; Survey; Multiple institutions
About this articleTitle
Comparison of patient-specific intensity modulated radiation therapy quality assurance for the prostate across multiple institutions
Journal
Reports of Practical Oncology and Radiotherapy
Issue
Pages
600-605
Published online
2019-11-01
DOI
10.1016/j.rpor.2019.09.009
Bibliographic record
Rep Pract Oncol Radiother 2019;24(6):600-605.
Keywords
Patient-specific IMRT QA
Consistency
VMAT
Survey
Multiple institutions
Authors
Kazuki Kubo
Hajime Monzen
Kohei Shimomura
Kenji Matsumoto
Tomoharu Sato
Mikoto Tamura
Kiyoshi Nakamatsu
Kentaro Ishii
Ryu Kawamorita