Abstract

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Title:: A new dose calibration method using EBT3 film for dose verification in intensity-modulated radiotherapy

Author(s):: LIU Zhiqiang; WEI Xiyi; AN Yongwei; LIU Tingting; NIU Ruijun; ZHAO Lin; GAO Liying; Department of Radiation Oncology, Gansu Provincial Cancer Hospital, Lanzhou 730050, China

Keywords:: ; Keywords: intensity-modulated radiotherapy; EBT3 film; dose calibration; dose verification; net optical density

Abstract:: Abstract: Objective To study the response characteristics of EBT3 film to X-ray irradiation, research a new dose calibration method using EBT3 film, and investigate the method and process of applying the proposed dose calibration method for dose verification in intensity-modulated radiotherapy. Methods A physical quantity, net optical density (netOD), was introduced during film dose calibration. The netOD transformed from the pixel value obtained after film scanning was converted to the calibration of dose value. Finally, the proposed method was used to validate an example of intensity-modulated radiotherapy plan for testing the calculation accuracy of treatment planning system. Results The dose response of EBT3 film to MV X-ray was nonlinear. The deviation due to the film and the scanning process was well removed by the dose calibration method with the introduction of netOD. The results of using the proposed dose calibration method for dose verification showed that the Gamma passing rate was above 98% based on the gamma criteria of 3%/3 mm. Conclusion The new dose calibration method using EBT3 film which can make the calculation of the dose distribution in film measurement more accurate and the film measurement more convenient can be used in clinical practice.