食管癌三维适形放疗中靶区移位与剂量学研究  

Target bias and dose study of patients with esophageal carcinoma during the treatment of three dimensional conformal radiotherapy

作　　者：吴丽鹏[1] 王澜[1] 韩春[1] 迟子锋[1] 张辛[1] 王军[1] 

机构地区：[1]河北医科大学第四医院放疗科,河北石家庄050011

出　　处：《中华肿瘤防治杂志》2009年第24期1953-1956,1960,共5页Chinese Journal of Cancer Prevention and Treatment

基　　金：河北省高校强势特色学科资助课题(200552)

摘　　要：目的:利用融合图像观察食管癌适形放疗过程中肿瘤区(GTV)的移位及体积变化情况,分析靶区变化对其受照剂量的影响,探讨食管癌三维适形放疗(3D-CRT)中二次定位的必要性及可行性。方法:40例食管癌患者接受3D-CRT,照射30Gy后行二次CT模拟定位。制定两套计划,治疗计划1(Plan1)按前半程追加处方剂量至60Gy;治疗计划2(Plan2)将后半程与前半程进行图像融合,总处方剂量60Gy,观察两套计划中GTV、CTV和PTV的受照剂量。结果:1)40例患者GTV几何中心在X、Y、Z轴上的移位分别为0.3、0.7和0.3cm,二次定位后的GTV体积、CT最大横径、最大前后径均较治疗前明显缩小,长度无明显缩短。2)Plan1中PTV2D95较PTV1D95减少约8.38%。3)Plan2中PTV2D95>PTV1D95。4)肿瘤长度>7cm、主动脉受侵者在Plan1中PTV2D95明显小于长度≤7cm及主动脉受侵阴性者。结论:食管癌3D-CRT过程中同时存在靶区移位及靶区缩小两种情况,由于靶区移位,可能会使PTV95%体积接受的剂量减少约8.38%,肿瘤长度较大合并主动脉受侵者建议行疗中二次CT定位以修正靶区剂量。OBJECTIVE：To observe the bias and volume change of gross tumor volume （GTV） during the treatment of three dimensional conformal radiotherapy（3D-CRT） for esophageal carcinoma by image fusion,to analyze the influence to dose distribution caused by target changes and explore the necessity and feasibility of the second CT simulation. METHODS：Forty patients with esophageal carcinoma were treated by 3D-CRT. After the first radiation of 30 Gy,they were rescanned by CT simulator with the same position and range. The CT images from the second simulation were transferred to the first treatment plan and image fusion was made simultaneously. Two treatment plans were designed for each patient. Plan 1：the total prescription dose of 60 Gy was delivered to PTV1. Plan 2 was designed by two phases,the first one being the same to plan 1. For the second one,prescription dose of 30 Gy was delivered to PTV2. The two-phase plans were fitted to plan 2. The doses of GTV,CTV,PTV were observed. RESULTS：1） The bias of geometrial center of GTV along X,Y,Z axis was 0.3,0.7,0.3 cm,respectively. The volume of GTV2,the maximum transverse and anteroposterior diameter scanned by the seconded CT simulation were significantly smaller than those of the first time,while the length of lesion was not significantly shorter. 2） In Plan 1,PTV2D95 was lower than PTV1D95 about 8.38%. 3） In Plan 2,PTV2D95 was higher than PTV1D95. 4） PTV2D95 from plan1 was significantly lower in the patients whose length of lesion 7 cm than that ≤7 cm,and the samd as in the patients whose aorta was invasioned than not. CONCLUTIONS：There were target bias and contraction during the treatment of 3D-CRT for esophageal carcinoma. The PTVD95 decreased about 8.38% due to the bias of target. For the patients whose length of lesion were comparatively long and aorta were invaded,we recommended a second CT simulation to modulate the dose of target.

关 键 词：食管肿瘤/放射疗法 二次定位 剂量分布 

分 类 号：R735.1[医药卫生—肿瘤]