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Comprehensive clinical evaluation of TomoEQA for patient-specific pre-treatment quality assurance in helical tomotherapy

 Changhwan Kim  ;  Min Cheol Han  ;  Young Kyu Lee  ;  Han-Back Shin  ;  Hojin Kim  ;  Jin Sung Kim 
 RADIATION ONCOLOGY, Vol.17(1) : 177, 2022-11 
Journal Title
Issue Date
Gamma Rays ; Humans ; Phantoms, Imaging ; Quality Assurance, Health Care ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted / methods ; Radiotherapy, Intensity-Modulated* / methods
Exit detector ; Helical tomotherapy ; Patient-specific pre-treatment quality assurance
Background: Based on a previous study on the feasibility of TomoEQA, an exit detector-based patient-specific pre-treatment quality assurance (QA) method for helical tomotherapy, an in-depth clinical evaluation was conducted.

Methods: Data of one hundred patients were analyzed to evaluate the clinical usefulness of TomoEQA for patient-specific pre-treatment QA in comparison with the conventional phantom-based method. Additional investigations were also performed under unusual measurement conditions to validate the off-axis region. In addition to the clinical evaluation of TomoEQA, a statistical analysis was conducted to determine the plan parameters that affect the pass/failure results of pre-treatment QA.

Results: The average and standard deviations of the gamma passing rate and point dose error for TomoEQA were comparable to those of the conventional QA method. For TomoEQA, the average values of the gamma passing rate and point dose error were 96.32% (standard deviation (1 sigma) = 3.94; 95% confidence interval (CI), 95.55 to 97.09) and - 1.12% (standard deviation (1 sigma) = 1.04; CI, - 1.32 to - 0.92), respectively. For the conventional QA method, the average values of the gamma passing rate and point dose error were 95.95% (standard deviation (1 sigma) = 4.35; 95% confidence interval (CI), 95.10 to 96.80) and - 1.20% (standard deviation (1 sigma) = 1.61; CI, - 1.52 to - 0.88), respectively. Further experiments on the off-axis region demonstrated that TomoEQA can provide accurate results for 3D dose analysis, which is inherently difficult in the conventional QA method. Through a statistical analysis based on the results of TomoEQA, it was validated that the total fraction (Total Fx), monitor units, beam-on-time, leaf-of-time below 100 ms, and planning target volume diameter were statistically significant for the pass/failure of the pre-treatment QA results.

Conclusions: TomoEQA is a clinically beneficial alternative to the conventional phantom-based QA method.
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1. College of Medicine (의과대학) > Dept. of Radiation Oncology (방사선종양학교실) > 1. Journal Papers
Yonsei Authors
Kim, Jinsung(김진성) ORCID logo https://orcid.org/0000-0003-1415-6471
Kim, Hojin(김호진) ORCID logo https://orcid.org/0000-0002-4652-8682
Han, Min Cheol(한민철)
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