鼻咽癌调强放射治疗摆位不确定度对危及器官计划体积(PRV)影响的研究  

Influence of Patient Setup Error on Planning Risk Volumes for Nasopharyngeal Carcinoma Patients Receiving Intensity-modulated Radiation Therapy

作　　者：林承光[1] 李国文[2] 刘晓臻[3] 林刘文[1] 赵充[1] 刘少鹏[1] 林览峰[1] 萧丽苹[1] 

机构地区：[1]华南肿瘤学国家重点实验室 [2]郑州大学第一附属医院放疗科,河南郑州450052 [3]广东省中医院放射科,广东广州510120

出　　处：《癌症》2008年第3期327-330,共4页Chinese Journal of Cancer

基　　金：广东省科技厅社会发展领域科技计划项目(No.2003-245);广东省自然科学基金项目(No.06021220)~~

摘　　要：背景与目的:在进行调强放射治疗(intensity modulated radiationtherapy,IMRT)计划设计时,危及器官的计划体积(planning risk volumes,PRVs)的定义对计划优化设计的结果影响很大。而PRV的设定与执行调强放射治疗时体位固定的不确定度有密切关系。本研究探讨鼻咽癌IMRT时需要设定的危及器官安全边界的大小。方法:选取首次做适形调强放疗的早期鼻咽癌患者19例。每周进行一次CT重复扫描,方法与做治疗计划时完全相同。共获取85次扫描参数。通过读图软件Osiris对每周扫描的CT图像与计划设计的CT图像进行比较,求出每次摆位与首次定位时感兴趣的解剖骨性标志点(这些骨性标志点代表视神经、脑垂体、脊髓、腮腺)在三维方向上的差异。结果:19例患者的85次CT扫描参数与计划CT扫描参数进行比较,视神经、脑垂体在X、Y、Z三个轴向的绝对位移值分别为(0.86±0.53)mm、(0.84±0.68)mm、(0.93±1.02)mm,轴向矢量位移的Σ(系统误差的标准差)分别为0.83mm、1.08mm、1.21mm,δ(随机误差的标准差)分别为0.85mm、0.83mm、1.14mm。脊髓、腮腺在X、Y、Z三个轴向的绝对位移值分别为(0.98±0.74)mm、(1.25±0.88)mm、(1.43±1.02)mm,轴向矢量位移的Σ分别为0.98mm、1.35mm、1.87mm,δ分别为1.02mm、1.46mm、1.54mm。结论:使用连续CT多次重复扫描的方法来研究鼻咽癌放射治疗时危及器官安全边界值的大小是可行的。BACKGROUND ＆ OBJECTIVE： Determination of planning risk volumes （PRVs） for an organ at risk greatly affects dose optimization in designing the intensity-modulated radiation therapy （IMRT） regimen. Patient setup errors have been found to closely correlate to the definition of PRVs. This study was to investigate the safety margin for the organ at risk during IMRT planning for nasopharyngeal carcinoma （NPC） patients, METHODS： Nineteen NPC patients （stage T1-2N0M0） who received IMRT for the first time were studied. Repeated computed tomography （CT） scans were performed for the patients once a week during the whole treatment course. A total of 85 CT scan reports were obtained, Differences between patient positioning of each time and first treatment setup were caluculated by comparing the anatomical landmarks （that is, optical nerve, pituitary, spine, and parotid） on each CT scan image using Osiris software. RESULTS： The displacement of optical nerve and pituitary in X, Y, and Z directions were, in absolute values, （0.86±0.53） mm, （0.84±0.68） mm, and （0.93±1.02） mm, respectively. The standard deviations （SDs） of systematic errors for the axial vector displacement were 0.83 mm, 1.08 mm, and 1.21 mm, while the SDs of random errors were 0.85 mm, 0.83 mm and 1.14 mm, The displacement of spine and parotid in X, Y, and Z directions were, in absolute values, （0.98±0.74） mm, （1.25±0.88） mm, and （1.43±1.02） mm, respectively, The SDs of systematic errors for axial vector displacement were 0.98 mm, 1.35 mm, and 1.87 mm, while the SDs of random errors were 1.02 mm, 1.46 mm, and 1.54 mm. CONCLUSION： It is feasible to determine the size of a safety margin of IMRT for organs at risk using repeated CT scans for NPC patients.

关 键 词：鼻咽肿瘤 放射疗法 摆位不确定度 随机误差 系统误差 安全边界 计划危及器官体积 

分 类 号：R739.63[医药卫生—肿瘤]