CAJ | 학술논문

目的评价和估算兆伏级锥形束CT(MV CBCT)成像系统在图像引导放疗中所致鼻咽癌患者的辐射剂量.方法选择MV CBCT系统头颈部8 MU扫描预案,利用0.65 cm~3指型电离室和CT头部剂量体模测量出体模不同位置的吸收剂量.并利用XiO治疗计划系统模拟MV CBCT扫描过程,计算体模电离室测量点的吸收剂量和鼻咽癌患者肿瘤靶区及危及器官的吸收剂量.结果体模不同位置吸收剂量的测量值和计算值具有很好的一致性,相对误差均小于3.5%.MV CBCT图像引导放疗所致鼻咽癌患者肿瘤靶区平均剂量为6.43 cGy,脑干、脊髓和视交叉的平均剂量分别为6.36、6.83和6.90 cGy,左、右视神经平均剂量分别为7.70和7.53 cGy,左、右腮腺平均剂量分别为6.86和6.43 cGy.结论使用治疗计划系统模拟MV CBCT图像采集过程估算剂量准确、可靠.在设计患者治疗计划时,要充分考虑MV CBCT图像采集过程所致患者剂量.
목적 평개화고산조복급추형속CT(MV CBCT)성상계통재도상인도방료중소치비인암환자적복사제량.방법 선택MV CBCT계통두경부8 MU소묘예안,이용0.65 cm~3지형전리실화CT두부제량체모측량출체모불동위치적흡수제량.병이용XiO치료계화계통모의MV CBCT소묘과정,계산체모전리실측량점적흡수제량화비인암환자종류파구급위급기관적흡수제량.결과 체모불동위치흡수제량적측량치화계산치구유흔호적일치성,상대오차균소우3.5%.MV CBCT도상인도방료소치비인암환자종류파구평균제량위6.43 cGy,뇌간、척수화시교차적평균제량분별위6.36、6.83화6.90 cGy,좌、우시신경평균제량분별위7.70화7.53 cGy,좌、우시선평균제량분별위6.86화6.43 cGy.결론 사용치료계화계통모의MV CBCT도상채집과정고산제량준학、가고.재설계환자치료계화시,요충분고필MV CBCT도상채집과정소치환자제량.
Objective To evaluate and estimate the patient doses from megavoltage cone-beam CT imaging system in the image-guided radiation therapy for nasopharyngeal carcinoma.Methods 8 MU protocol of the MV CBCT system was selected for the head-and-neck region.The absorbed doses at the different positions in the phantom were measured using a 0.65 cm~3 ion chamber and the cylindrical acrylic phantom.The absorbed doses at the measurement positions of the phantom were calculated and the patient doses to the tumor and critical organs were derived from dose-volume histogram by the TPS mimicking the MV CBCT scanning with 8 MU protocol.Results The error between the measured dose and the calculated dose was less than 3.5%.The average doses to the tumor target,brain stem.spinal Cord and ehiasm were 6.43,6.36,6.83 and 6.90 cGy,respectively,while those to left and right of both optic nerve and parotid were 7.70 and 7.53 cGy,7.70 and 7.53 cGy,respectively.Conclusion The patient doses estimated using the TPS mimicking the M V CBCT image acquiring procedure are accurate and reliable.The patient doses from the MV CBCT imaging must be considered when treatment plan of the patient is designed.