Division of Gastroenterology and Hepatology, University of Colorado Denver, Aurora, Colorado 80045-2541, USA.
Gastrointest Endosc. 2011 Jun;73(6):1109-14. doi: 10.1016/j.gie.2011.02.001.
Self-expandable metal stents (SEMSs) are used for palliation of malignant dysphagia. It is not known whether dose adjustments are required when there is a stent in the radiation field.
To measure the effects of esophageal stents of various designs and materials on radiation dose to the tissue adjacent to the stent in the radiation field to determine whether there should be any dose adjustment.
Simulated clinical protocol.
Linear accelerator radiation treatment center.
Solid Water phantoms were used to mimic the tissue environment of the human esophagus as well as stents of various designs and materials and controls.
Radiation beams composed of photons (x-rays) delivered in split dosing with energies of 6, 10, and 15 million volts.
Film and image-based evidence of dose enhancement; Monte Carlo calculations.
Dose enhancement from single beams was seen only on the anterior surface, particularly in the stainless steel Z-stent (3.5%-7.8%) and the nonmetal Polyflex stent (5.5%-8.8%); less dose enhancement was seen on the anterior surface of the Alimaxx and Ultraflex nitinol stents (2%-2.5%). A negligible dose effect was seen on the posterior wall of all the stents tested. Monte Carlo calculation results were roughly similar to actual dosimeter measurements.
Simulated clinical protocol.
This tissue-mimicking model reveals that radiation dose enhancement is a function of stent design and material, and the dose reduction is unnecessary as long as multiple fields are used.
自膨式金属支架（SEMS）用于缓解恶性吞咽困难。目前尚不清楚在放射野中有支架时是否需要调整剂量。
测量不同设计和材料的食管支架对放射野中支架相邻组织的辐射剂量的影响，以确定是否需要进行任何剂量调整。
模拟临床方案。
直线加速器放射治疗中心。
使用实心水体模模拟人体食管的组织环境以及各种设计和材料的支架和对照物。
由光子（X 射线）组成的放射束，以 6、10 和 1500 万伏的能量进行分次照射。
胶片和图像证据表明剂量增强；蒙特卡罗计算。
仅在前表面观察到单束剂量增强，尤其是在不锈钢 Z 支架（3.5%-7.8%）和非金属 Polyflex 支架（5.5%-8.8%）中；Alimaxx 和 Ultraflex 镍钛诺支架在前表面的剂量增强较小（2%-2.5%）。所有测试支架的后壁几乎没有剂量效应。蒙特卡罗计算结果与实际剂量计测量结果大致相似。
模拟临床方案。
这种组织模拟模型表明，辐射剂量增强是支架设计和材料的函数，只要使用多个射野，就不需要进行剂量减少。
