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目的:研究不同材料不同厚度的施源器对192Ir源近距离放射治疗剂量分布的影响。方法:选取不锈钢和塑料两种常用的施源器材料,不锈钢的厚度有0.05cm、0.1cm、0.2cm、0.3cm、0.4cm和0.5cm六种,塑料的厚度有0.1cm、0.3cm、0.5cm、1.0cm、1.5cm和2.0cm六种,利用EGSnrc程序,模拟体模中有施源器和无施源器时的剂量分布,对比分析施源器材料和厚度对剂量分布的影响。结果:不锈钢施源器产生的剂量偏差随厚度的增加而增大,在厚度小于0.1cm的情况下,径向方向2cm范围内剂量偏差不超过3%,厚度超过0.1cm时,剂量偏差超过5%。塑料施源器剂量偏差与厚度之间无明显关系,在厚度小于2cm的情况下,径向方向3cm范围内误差在3%的范围内。结论:在近距离放射治疗应尽量选用塑料材质的施源器,需要考虑不锈钢施源器对剂量分布的影响。
OBJECTIVE: To study the effect of different thickness and thickness of applicator on the dose distribution of 192Ir brachytherapy. Methods: Two commonly used stainless steel and plastic applicator materials were selected. The thickness of stainless steel is 0.05cm, 0.1cm, 0.2cm, 0.3cm, 0.4cm and 0.5cm. The thickness of plastic is 0.1cm, 0.3cm, 0.5 cm, 1.0cm, 1.5cm and 2.0cm. The EGSnrc program was used to simulate the dose distribution in the phantom with or without applicator. The effects of the applicator material and thickness on the dose distribution were compared. Results: The dose deviation of stainless steel applicator increased with the increase of thickness. When the thickness was less than 0.1 cm, the dose deviation within 2 cm in the radial direction did not exceed 3%. When the thickness exceeded 0.1 cm, the dose deviation exceeded 5 %. There is no obvious relationship between the dose deviation and the thickness of plastic applicator. When the thickness is less than 2cm, the error within 3cm in the radial direction is within 3%. CONCLUSIONS: Plastic source applicators should be selected for brachytherapy and the effect of stainless steel applicator on dose distribution should be considered.