全身皮肤电子束照射剂量学参数的测量和讨论

The measurement and discussion of the dose parameters of the total skin electron irradiation

目的对全身皮肤电子束照射(TSEI)的剂量学参数进行测量并讨论。方法采用双机架角多野照射技术,在源皮距等于380cm下对6、8MeV电子束相关照射野的剂量学参数进行测量。采用平行板电离室和半导体探头测量百分深度量;用半导体探头测量均匀模体内某一深度处各点剂量均匀性,用剂量胶片测量人体体模横截面的剂量分布。结果对于6、8MeV电子束双机架角6个野照射,最大剂量深度都在0～3mm处,6MeV的80%、50%剂量深度分别在7、14mm处,8MeV的80%、50%剂量深度分别在7、17mm处。在机架旋转方向上模体2、11mm深度处野内各测量点的剂量均匀性在10%～+3%内。得出了人体模脐部横断面内等剂量分布曲线。结论全身皮肤电子束照射的剂量学参数与常规单野照射的剂量学参数有较大区别,临床治疗前需要准备充分的临床剂量学资料。

Objective To measure and discuss the dose parameters of Total skin electron irradiation (TSEI). Methods Using the Dual angle fields irradiation technique, the dose parameters of 6?MeV and 8?MeV electron beam irradiation was measured while SSD is equal to 380?cm. The percent depth dose (PDD) is measured with Parallel-Plate chamber and Semiconductor detectors, the dose uniformity in certain depth in the Phantom was measured with Semiconductor detectors, the isodose in the human phantom traverse is measured with film. Results For 6?MeV and 8?MeV electron using Dual angle fields irradiation, the dose maximum is located at a depth of 0-3?mm, for 6?MeV the 80% and 50% dose depth at 7?mm. and 14?mm, for 8?MeV the 80% and 50% dose depth at 7?mm. and 17?mm. In the direction of gantry rotation the dose uniformity in the phantom of 2?mm and 11?mm depth is-10% to 3% of the measurement points. The isodose of the navel transverse plane is shown. Conclusions There is much difference of dose parameters between TSEI and general single beam radiation. Before clinical treatment enough clinical dose information must be prepared.