鼻咽癌调强放射治疗的剂量验证  

Dosimetric Verification of Intensity Modulated Radiotherapy for Nasopharyngeal Carcinoma Patients

作　　者：余建义[1] 易金玲[1] 吴式琇[1] 张力[1] 

机构地区：[1]温州医学院附属第一医院放疗科,浙江温州325000

出　　处：《中国医学物理学杂志》2008年第5期790-793,共4页Chinese Journal of Medical Physics

基　　金：浙江省科技厅重大与高发疾病防治专项(2007C13054);温州市科技局重大项目(s20070026)资助

摘　　要：目的:对接受调强放射治疗的鼻咽癌病人进行治疗前的剂量验证。材料和方法:利用电离室,胶片和验证模体对39个接受调强放射治疗的鼻咽癌患者,在治疗开始前进行绝对剂量和相对剂量验证。绝对剂量验证主要在两个位置进行:一个在等中心位置,另一个在离等中心4 cm靠进腮腺的位置。相对剂量主要用体模对单野和整个计划的剂量分布进行验证。将得到的剂量分布利用分析软件与计划中的剂量分布进行分析比较。利用剂量偏差(dose difference)、吻合距离(distance to agreement,DTA)、γ指数等参数来测量剂量验证的偏差。结果:中心点和腮腺边上点的平均绝对误差分别为2.70%和3.03%。对于测量感兴趣区域(ROI,region of interested)的相对误差的测量,90%的测量都在设定的标准(3%,3 mm)之内,对于未能达到剂量偏差和间距偏差标准的区域,结合γ分析后一般也可以得到满意的结果。结论:验证结果表明实际测量剂量分布与计划计算的剂量分布符合的相当理想。Objective： To verify the dose accuracy of intensity modulated radiotherapy （IMRT） for nasopharyngeal carcinoma patients. Materials and Methods： Absolute and relative dose difference were measured before the implementation of IMRT for 39 nasopharyngeal carcinoma patients by using ionization chamber, films and phantom. Absolute dose verification was carried out on two points： one is isocenter, and the other is 4 cm away of isocenter. Relative dose difference was performed both for individual field fluence and composite plan. The measured dose distributions was compared with planned dose distribution by applying parameters of dose difference, distance to agreement （DTA） and γ index. Results： The average absolute dose differences in isocenter and the point 4cm away ofisocenter are 2.07% and 3.03%, respectively.90% of the relative dose measurements are within our protocol （3%,3 mm） in region of interested （ROI）.The remained 10% measurement was also satisfied by applying γ analysis. Conclusion： Excellent agreement between the measured and planned dose distribution has been observed in IMRT for nasopharyngeal carcinoma patients.

关 键 词：鼻咽癌 调强放射治疗 剂量验证 

分 类 号：R73[医药卫生—肿瘤]