使用兆伏级锥形束CT进行头颈部剂量计算的研究  

Megavoltage cone-beam CT in the use of head and neck dose calculation

作　　者：常熙[1,2] 李龙根[1,2] 徐志勇[1,2] 邱健健[1,2] 胡伟刚[1,2] 蒋国梁[1,2] 

机构地区：[1]复旦大学附属肿瘤医院放射物理研究室 [2]复旦大学上海医学院肿瘤学系

出　　处：《中华放射肿瘤学杂志》2008年第5期385-388,共4页Chinese Journal of Radiation Oncology

摘　　要：目的考察使用兆伏级锥形束CT（MVCBCT）进行头颈部剂量计算的可行性和准确性。方法采用可进行MVCBCT扫描的西门子ONCOR直线加速器，扫描MiniCTQC模体，建立MVCBCT值密度曲线；分别采集模体和鼻咽癌病例的常规CT和MVCBCT图像。在模体的常规CT上设计两种单野计划，往鼻咽癌的常规CT上设计IMRT计划，将完全相同的计划分别应用于模体和鼻咽痛的MVCBCT图像。应用MVCBCT值密度校正曲线计算靶区及正常组织的受量，并与使用常规CT计算所得的剂量分布做比较。结果绝对剂量和剂量点距离比较结果显示，在单野方案中所有MVCBCT与常规CT剂最偏差〈3％和剂量点距离〈3mm。在IMRT计划中DVH显示常规CT和MVCBCT计划曲线有很好的一致性，常规CT与MVCBCT计算所得最大差值为95cGy，误差为1．4％。绝对剂量和剂量点距离比较结果显示在等中心平面机架角度0°、45°、90°、120°、160°、200°、240°、280°、320°的通过率为95．5％、99．4％、93．8％、98．7％、100％、94．5％、97．3％、95．6％、99．3％、99．4％。结论使用兆伏级锥形束CT进行头颈部剂量计算可行且可得到与常规CT基本一致的剂量分布。Objective To evaluate the feasibility and accuracy of performing dose calculation on megavohage cone-beam CT（MVCBCT） in the head and neck. Methods MiniCTQC phantom was imaged using MVCBCT scanner,and the MVCBCT value density calibration curve was established. Conventional CT and MVCBCT image of phantom and nasopharyngeal carcinoma（NPC） patient were acquired respectively. Two kinds of single field plan were designed for conventional CT image of phantom, and IMRT plan was used for conventional CT image of a NPC patient. The conventional CT plans were copied to MVCBCT image. The dose distribution was calculated for targets and normal tissues using the MVCBCT value density calibration curve,and compared with that of conventional CT. Results For all the cases,the differences between the calculated dose distributions using MVCBCT and CT were less than 3% and 3 mm in single field plan. In IMRT plan,DVHs of conventional CT and MVCBCT were in excellent agreement. The biggest difference between conventional CT and MVCBCT was 95 cGy with the error of 1.4%. On the isocenter plane,the passing rate was 95.5% , 99.4% , 93.8% , 98.7% , 100% , 94.5% , 97.3% , 95.6% , 99.3% and 99.4% for the beam angle of 0° ,45° ,90° ,120° ,160°,200° ,240° ,280° and 320°. Conclusions Performing dose calculation using MVCBCT in head-and-neck region was feasible,and the dose distributions on the conventional CT and MVCBCT were in excellent agreement.

关 键 词：X线摄影术 计算机 兆伏级锥形束 剂量学 

分 类 号：R686[医药卫生—骨科学]