摘要目的 用热释光剂量计(TLD)和胶片测量调强放疗(IMRT)光子线束吸收剂量和二维剂量分布.方法 采用非概率抽样方法,在河南省选择5家三级甲等医院的8台可开展IMRT的医用加速器,TLD放入国家原子能机构(IAEA)提供的聚苯乙烯固体模体(15 cm×15 cm×15 cm)中,经CT扫描,影像传给放射治疗计划系统(TPS)制定放疗计划,源皮距90 cm,深度10 cm,照射野5 cm×5 cm,6MVX射线,计算吸收剂量6 Gy和相应的监督单位(MU),实施IMRT计划照射模体,测量TLD吸收剂量,同样方法测量胶片吸收剂量.医院的均质固体模体,尺寸30 cm×30 cm,厚度20 cm,25 cm×25 cm的胶片放在模体中,源皮距95 cm,深度5 cm,实施IMRT计划.结果 调查的8台医用加速器中,有7台加速器的TLD吸收剂量相对偏差符合要求,1台加速器不符合要求;胶片吸收剂量相对偏差全部符合要求;7台加速器的二维剂量分布通过率符合要求,1台加速器不符合要求.结论 TLD和胶片用于核查调强放疗多叶光栅野吸收剂量和二维剂量分布,方法简单,可操作性强,适合在我省医院大范围实施IMRT剂量质量核查.

abstractsObjective To validate the absorbed dose and two-dimensional dose distribution from photon beam by using Thermoluminescent dosimeter (TLD) and film for intensity modulated radiation therapy (IMRT).Methods A total of 8 medical accelerators were selected among 5 third-grade first-class hospitals using non-probabilistic sampling method in Henan province.TLDs were put into polytetrafluoroethylene solid phantom with size of 5 cm × 15 cm × 15 cm provided by IAEA.After CT scanning,the radiotherapeutic plans were formulated through image transmission to the treatment planning system (TPS).The IMRT plan was implemented for measurement of TLD-absorbed doses under the conditions of 5 cm × 5 cm field,90 cm SSD,10 cm depth,6 MV photon beam and 6 Gy absorbed dose and corresponding measurement unit (MU).The 25 cm × 25 cm film-absorbed dose measurement was made in the same manner as TLD under the conditions of 30 cm × 30 cm size,20 cm thickness,95 cm SSD and 5 cm depth.Results Of eight accelerators,the requirements can be met for 7 accelerators with respect to the relative deviation of TLD absorbed dose except 1.For film,relative deviations were all consistent with the requirements.The passing rate of two-dimensional dose distribution was in line with the requirements for 7 accelerators except 1.Conclusions TLD and film can be used to check the MLC field absorbed dose and two-dimensional dose distribution.This methodis simple,easy to operate and suitable for the implementation of IMRT quality control in hospitals in Henan province.