【摘要】 目的:探讨放射治疗中真空袋和热塑面膜对皮肤剂量的影响及其特点。方法:通过实验测量固体水不同深度处表面加和不加真空袋/热塑面膜时的剂量,计算加真空袋或热塑面膜时皮肤剂量的增加值和最大剂量点剂量的变化规律。结果:热塑面膜在固体水表面处剂量增高了42.5%,表面下1mm处剂量增高了23.8%;1.5cm厚的真空袋在固体水表面处剂量增高了47.7%,表面下1mm处剂量增高了26.9%;5cm厚的真空袋在固体水表面处剂量增高了94.2%,表面下1mm处剂量增高了54.2%;随固体水深度的增加剂量增高值逐步降低。最大剂量深度处的剂量变化三种情况下均不大,小于等于1%。结论:真空袋和热塑面膜对最大剂量深度处的剂量影响可忽略不计,但它们对皮肤及表面组织剂量的影响很大,存在表面超剂量现象,必须引起临床医师和物理师的注意,以防严重放射并发症的发生。为了确保肿瘤得到足量照射又使得皮肤剂量不至造成严重并发症,真空袋的厚度以不超过3cm为宜。更多还原

【Abstract】 Purpose: To study the effect of vacuum bag and thermoplastic sheet on skin dose in radiotherapy. Methods:First we measured the dose for several depths with and without vacuum bag/thermoplastic sheet on Elekta synergy medical linear accelerators. Then we got the increase of surface dose and dmax dose with vacuum bag/thermoplastic. Results: The dose was increased 42.5% at the surface of solid water and was increased 23.8% at the 1 mm depth when using thermoplastic sheet; the dose was increased 47.7% at the surface of solid water and was increased 26.9% at the 1 mm depth when the thickness of vacuum bag was 1.5 cm; the dose was increased 94.2% at the surface of solid water and was increased 54.2% at the 1mm depth when the thickness of vacuum bag was 5 cm. The variation of dose at the dmax was less than 1% for these three cases. Conclusion: The increase of dmax dose with vacuum bag/thermoplastic can be ignored, but the increase of surface dose is large and can not be ignored. There is a so-called Skin Ultra Dose phenomenon, the doctors and physicists must pay attention to this phenomenon. In order to ensure the dose to tumor is right and the damage to skin dose is slight, we believe the thickness of vacuum bag must be less than 3 centimeter.更多还原