不同处理方法在CT扫描不全时对放疗计划剂量的影响——以鼻咽癌为例  

Influence of Different Treatments on Planned Radiation Dose during Incomplete CT Scans-Take Nasopharyngeal Cancer as an Example

作　　者：刘敏[1,2] 张达[2] 王炳杰 何勇 廖雄飞[2] 姚杏红[2] 袁珂 杨凤[2] 黎杰 Liu Min;Zhang Da;Wang Bingjie;He Yong;Liao Xiongfei;Yao Xinghong;Yuan Ke;Yang Feng;Li Jie(Chengdu University of Technology,Institute of Nuclear Technology and Automation Engineering,Chengdu 610041,Sichuan,China;Radiation Oncology Key Laboratory of Sichuan Province,Sichuan Clinical Research Center for Cancer,Sichuan Cancer Hospital&Institute,Sichuan Cancer Center,Affiliated Cancer Hospital of University of Electronic Science and Technology of China,Chengdu 610041,Sichuan,China;Department of Electrical and Computer Engineering,Faculty of Science and Technology,Univeristy of Macao,Macao 999078,China)

机构地区：[1]成都理工大学核科学与自动化工程学院,成都610041 [2]四川省肿瘤临床医学研究中心,四川省肿瘤医院·研究所,四川省癌症防治中心,电子科技大学附属肿瘤医院放射肿瘤学四川省重点实验室,成都610041 [3]澳门大学科技学院电机及电脑工程系,中国澳门999078

出　　处：《肿瘤预防与治疗》2023年第8期669-680,共12页Journal of Cancer Control And Treatment

基　　金：四川省科技厅重点研发项目(编号:22ZD YF0898);电子科技大学肿瘤医工创新基金(编号:ZYGX 2021YGCX002);四川省肿瘤医院优秀青年基金项目(编号:YB2021030)。

摘　　要：目的:在放疗临床中,当CT扫描不全时由于射线散射体积不足,会影响剂量计算的准确性。对此一般有两种近似处理方法:(1)复制最后一层CT并延申5 cm;(2)在最后一层增加5 cm等效水。本文以鼻咽癌容积旋转调强放疗为例,研究了不做处理、采用以上两种处理方式与完整CT患者在计划系统中计算剂量的差异。方法:选取CT扫描完整的初治鼻咽癌患者21例,其原CT命名为CT0,在靶区往脚方向最后一层截断后,头方向有靶区的CT部分命名为CT_(cut),方法1处理为CTcopy,方法2处理为CT_(water)。在CT_(cut)、CT_(copy)和CT_(water)上设计放疗计划P_(cut)、P_(copy)和Pwater,将这些计划的射野信息复制到CT0,重新计算剂量,得到计划P_(cut0)、P_(copy0)和P_(water0)。分别对比P_(cut0)和P_(cut)、P_(copy0)和P_(copy)以及P_(water0)和P_(water)的剂量参数。结果:P_(cut0)和P_(cut)比较,预防照射区PCTVln剂量学参数D_(95)、V_(5760)差异有统计学意义(P<0.05)。采用方法一,P_(copy0)和P_(copy)对比,PCTVln各参数差异无统计学意义(P>0.05);方法二,P_(water0)和P_(water)比较,剂量学参数D_(95)、V_(5760)差异有统计学意义(P<0.05)。虚拟靶区PTV0-1和PTV1-2有类似的结果,P_(cut0)和P_(cut)比较,剂量学参数D_(90)、D_(95)、V_(5760)差异有统计学意义(P<0.05),但P_(copy0)和P_(copy)比较,各剂量学参数差异无统计学意义(P>0.05),P_(water0)和P_(water)比较,仅D95、V5760等参数变化差异有统计学意义(P<0.05)。虚拟靶区PTV2-5在所有比较中差异均无统计学意义(P>0.05)。仅P_(copy0)和P_(copy)对比时,危及器官D_(1cc)差异有统计学意义(P<0.05)。结论:CT截断对剂量的影响仅限于CT最后一层2 cm范围内,两种近似处理方式都可以纠正靶区和危及器官的剂量学偏差,物理师可根据临床实际选择近似处理方法,但需要严格限制危及器官剂量。Objective:In the clinical practice of radiotherapy,the accuracy of dose calculation will be affected by insufficient scattering volume when CT scan is incomplete.In this case,two approximate processing methods are usually used(:1)copy the last CT layer and extend it for 5 cm;(2)add 5 cm equivalent water to the last CT layer.In this paper,we took volumetric modulated arc therapy for nasopharyngeal carcinoma as an example,and investigated the dosimetric difference amongst 3 ways:the above 2 treatments and no treatment.Methods:21 patients with primary nasopharyngeal carcinoma were recruited.The original CT was named CT_0.After truncation,CT with target was named CT_(cut).CT_(cut)treated with method1 was named as CT_(copy),and CT_(cut)treated with method 2 was named as CT_(water).We designed treatment plans P_(cut),P_(copy)and P_(water)on CT_(cut),CT_(copy)and CT_(water)respectively.And then,we copied the field information of those plans to CT_0,calculated the doses,and got plans P_(cut0),P_(copy0)and P_(water0).The dosimetric parameters of P_(cut0)vs P_(cut),P_(copy0)vs P_(copy),and P_(water0)vs P_(water)were compared respectively.Results:For target PCTVln,there were significant differences in the dosimetric parameters D_(95)and V_(5760)(P<0.05)in P_(cut0)and P_(cut).In method 1,there were no significant differences in PCTVln parameters between P_(copy0)and P_(copy)(P>0.05).In method 2,differences in the dosimetric parameters D_(95)and V_(5760)between P_(water0)and P_(water)were statistically significant(P<0.05).Similar results were found in virtual target areas PTV_0-_1 and PTV_1-_2.There were statistically significant differences between P_(cut0)and P_(cut)in dosimetric parameters D_(90),D_(95)and V_(5760)(P<0.05),but there were no statistically significant differences in dosimetric parameters between P_(copy0)and P_(copy)(P<0.05).Differences in D_(95)and V_(5760)between P_(water0)and P_(water)were statistically significant(P<0.05).There were no statistically significant differences in all dosimetric parameters in

关 键 词：鼻咽癌 CT扫描不全 射线散射体积 近似处理 剂量学 

分 类 号：R739.63[医药卫生—肿瘤] R730.55[医药卫生—临床医学]