摘要
目的 研究食管内置金属支架对放射治疗剂量的影响 ,以便在临床应用中进行适当修正。方法 采用热释光元件测量。测量探测器为国产Fj 42 7A热释光剂量仪 ,热释光元件为LiF(Mg,P ,Cu)片状型剂量元件。分别测量两种 (进口及国产 )食管内置网状金属支架及未放支架的石蜡体模 ,测量支架周围 (即食管粘膜处 )的剂量并与无支架时食管中心点的剂量进行比较。结果 国产支架单野垂直照射时沿射束方向 ,支架前点和后点对60 Coγ射线和 4、6MVX射线剂量增加分别为16 .2 %和 7.8%、15 .4%和 6 .8%、12 .8%和 5 .8% ,进口支架单野垂直照射剂量增加分别为 13.0 %和7.0 %及 11.7%和 6 .0 %、8.5 %和 3.2 % ;前后两野对穿照射剂量增加 11.7%～ 2 4.0 % ,3个野交角照射支架周围 (食管粘膜 )均增加 3.2 %～ 16 .2 %。结论 置放食管网状金属支架后进行常规放射治疗时 ,单次剂量最好≤ 1.7Gy ,前后对穿野照射时≤ 1.5Gy。建议使用直径 <1.5cm支架 ,选用
Objective To study the dose distribution of intra-cavitary NiTi metal-stent for correction in radiotherapy of esophageal carcinoma.Methods Thermoluminescence Dosimeter(TLD) with LiF dose units was used to simulate the dose variation in wax phantom with or without Chinese and Japanese metal stents in esophageal lumen on 60Co, 4 MV X-ray and 6 MV X-ray machines. The dose distribution on the stent fringe (i.e.,on the esophageal mucosa) was compared with that at the center of esophagus without metal stent.Results When a single anterior field was used to irradiate the esophageal carcinoma, the dose enhancement on the anterior and posterior point of the Chinese metal stent was 16.2% and 7.8% by 60Co,15.4% and 6.8% by 4 MV X-ray and 12.8% and 5.8% by 6 MV X-ray. With the same set-up, the dose enhancement of Japanese stent was 13.0% by 6 MV X-ray. When anterioposterior and posterioanterior (AP/PA) opposing fields were used ,the dose enhancement ratio was 11.7%～24.0%. When three fields from three different directions were used ,the dose were increased by 3.2～16.2%.Conclusions When irradiating esophageal carcinoma with intra-cavitary metal stent,we suggest the fraction dose be below 1.7 Gy when one field is used and not exceed 1.5 Gy when AP/PA fields are used. It is advisable to use the three field technique with the diameter of the stent limited to 1.5 cm.
出处
《中华放射肿瘤学杂志》
CSCD
北大核心
2001年第4期262-264,共3页
Chinese Journal of Radiation Oncology
