摘要
目的比较胸中段食管癌不同入射角度5野调强放疗计划靶区剂量及正常组织剂量。方法8例胸中段食管癌患者，每例设计3个5野调强计划，IMRTl用前后对穿＋右前左后对穿＋左前斜野，其中右前左后野避开脊髓；IMRT2入射角等分，即0°，72°，144°，216°和288°；IMRT3入射角优化为0°，50°，150°，210。和310°。比较3个计划的阴V平均剂量（Dmean）、均匀性指数（HI）和适形度指数（CI）；总肺V5、V10、V20和V30；脊髓最大剂量（Dmax）；心脏V30、V40和平均剂量（Dmean）。计划要求：90％等剂量线覆盖95％胛V体积和100％GTV体积，剂量为6000cGy／30次，总肺V20≤28％，对心脏无特殊限量，控制脊髓剂量在4200cGy-4300cGy范围内。结果3个计划PTV的Dmean、HI和CI差异有统计学意义（P〈0．05），3个指标的平均值均以IMRT2最大，IMRT3次之，IMRTl最小，但HI在IMRT2与IMRT3问无统计学差异（P〉0．05）。总肺V5和V30差异有统计学意义（P〈0．05），其中V5以IMRT2最大，IMRTl次之，IMRT3最小，但IMRTl与IMRT3间无统计学差异（P〉0．05）；V30以IMRT2最小，IMRTl次之，IMRT3最大，但仅IMRT2和IMRT3间差异有统计学意义（P〈0．05）；总肺V10、V20和Dmean，脊髓最大剂量Dmax，心脏V30、V40和Dmean差异无统计学意义（P〉0．05）。结论角度优化的IMRT3计划较采用对穿野的IMRTl计划能提高靶区适形性（cI），较角度均分的IMRT2计划能降低总肺v5体积和靶区平均剂量（Dmean）。
Objective To compare the difference of dosimetric results in IMRT plans with 5 -field for thoracic middle esophageal carcinoma. Methods Eight patients with thoracic middle esophageal carcinoma were involved in this study. Three IMRT plans with 5 - field were designed for each patient. Plan IMRT1 included one anterior oblique field of patient left and two pairs of parallel - opposed fields. One pair of parallel - opposed fields were antero - posterior and postero - anterior（ AP - PA）. Another pair of f parallel - opposed fields were anterior oblique of patient right and posterior oblique of patient left which required to avoid the spinal cord. The fields of plan IMRT2 were equispaced, including 0°,72°, 144° ,216°and 288°. The fields of plan IMRT3 were optimized, including 0° ,50°, 150° ,210°and 310°. Evaluation parameters included ： mean dose （Dmean） , homogeneity index （HI） and conformity index （CI） of PTV ; V5, V10, V20 and V30 of total lung ; V30, V40 and Dmean of heart; Dmax to the spinal cord. The aim of IMRT was follows：prescribed dose of 6 000 cGy/30Fx to 95% of PTV and 100% GTV. V20 of total lung≤28%. The doses of heart were not limited. Dmax to the spinal cord were between 4200 cGy - 4300 eGy. Results Significant differences of Dmean, HI and CI of PTV were obtained among the three plans（ P 〈 0.05 ）. All of the three evaluation parameters values in plan 1MRT2 were higher than plan IMRT3. Plan IMRT3 were higher than plan IMRT1. But there were no significant difference of HI values between plan IMRT3 and plan IMRT2 （ P 〉 0.05 ）. Significant differences of V5 and V30 of total lung were obtained among the three plans （P 〈 0.05 ）. V5 values in plan IMRT2 were higher than plan IMRT1, and plan IMRT1 were higher than plan IMRT3. But there were no significant difference of V5 values between plan IMRT1 and plan IMRT3 （ P 〉 0.05 ）. Among the three plans, V30 values in plan IMRT2 were the lowest one;plan IMRT1 were the second one, and plan IMRT3 were the highest one. There were significant difference of V30 values in plan IMRT2 and plan IMRT3 （P 〈 0.05 ）. There were no significant differences of V10, V20 and Dmean of total lung, cord Dmax. V30, V40 and Dmean of heart were among the three plans （ P 〉 0.05 ）. Conclusions Plan IMRT3 with angle optimized ra- diation fields improved CI of PTV, compared to IMRT1 in which parallel - opposed radiation fields were adopted. Plan IMRT3 had the advantage in reducing V5 of total lung and Dmean of PTV, compared to plan IMRT2 in which equispaced radiation fields were adopted.
出处
《实用肿瘤学杂志》
CAS
2012年第3期251-255,共5页
Practical Oncology Journal
关键词
食管癌
调强放疗
剂量学
Esophageal carcinoma
Intensity- modulated radiation therapy（IMRT）
Dosimetric study
