CAJ | 학술논문

目的基于电子射野影像装置(EPID)建立二维剂量精确重建模型并验证容积调强弧形治疗(VIMAT)剂量,与其他测量工具进行比较与分析.方法采用EPID进行VIMAT的二维剂量验证,基于卷积、反卷积以及修正函数建立二维剂量重建模型.通过电离室测量的离轴比剂量曲线并用最小二乘法确定计算模型参数.对12例不同部位肿瘤患者的VIMAT计划用电离室测量中心点剂量,采用其他平面剂量测量工具测量相应平面剂量分布.所有工具测量深度均设置为10 cm,并采用γ分析法比较测量结果.结果对中心点绝对剂量,EPID与电离室测量结果偏差＜1.5％.对平面剂量,2％2 mm标准下EPID与Seven29、Matrixx的平均γ通过率分别为98.9％、99.8％,3％3 mm标准下EPID与治疗计划系统计算结果的平均γ通过率为99.9％.结论基于EPID建立的二维剂量重建模型能很好地用于调强放疗二维剂量验证工作,今后将考虑将该模型拓展到均匀模体的三维剂量验证中.
목적 기우전자사야영상장치(EPID)건립이유제량정학중건모형병험증용적조강호형치료(VIMAT)제량,여기타측량공구진행비교여분석.방법 채용EPID진행VIMAT적이유제량험증,기우권적、반권적이급수정함수건립이유제량중건모형.통과전리실측량적리축비제량곡선병용최소이승법학정계산모형삼수.대12례불동부위종류환자적VIMAT계화용전리실측량중심점제량,채용기타평면제량측량공구측량상응평면제량분포.소유공구측량심도균설치위10 cm,병채용γ분석법비교측량결과.결과 대중심점절대제량,EPID여전리실측량결과편차＜1.5％.대평면제량,2％2 mm표준하EPID여Seven29、Matrixx적평균γ통과솔분별위98.9％、99.8％,3％3 mm표준하EPID여치료계화계통계산결과적평균γ통과솔위99.9％.결론 기우EPID건립적이유제량중건모형능흔호지용우조강방료이유제량험증공작,금후장고필장해모형탁전도균균모체적삼유제량험증중.
Objective To develop an accurate 2D dose reconstruction model using electronic portal imaging device (EPID).2D dosimetric verifications of volumetric intensity-modulated arc therapy (VIMAT)were done using the model.And the results were compared to other dosimeters.Methods The EPID-based dose reconstruction model was using convolve,deconvolve and correction function.The dose profiles which were obtained by the ion chamber were used to determine the model parameters.A total of 12 VIMAT plans for the treatment of anatomical sites of various complexities were chosen.The results obtained from EPID were compared to other dosimeters and treatment planning system (TPS).The ion chamber was used to measure the central point absolute doses.Other dosimeters were used to measure the plane dose distributions.All dosimeters measured the dose at 10 cm depth.The results were analyzed using γevaluation method.Results Regarding absolute central point doses,the ion chamber results were within 1.5％ of the EPID results.For the comparison to Seven29 and Matrixx,the average γ pass rates with 2％and 2 mm criteria were 98.9％ and 99.8％ respectively.For the dose distributions measured by EPID and calculated by TPS,the γ pass rates with 3％ and 3 mm criteria were 99.9％.Conclusions The presented results which were obtained from the comparison of measured and calculated doses show the reliability of our EPID-based dose reconstruction model.With the model,EPID can be a reliable and fast tool for IMRT plan dosimetric verification.The model expanded to the 3D dosimetric verification in the uniform phantom will be considered as the next work.