宫颈癌VMAT与静态IMRT所致全身当量剂量比较

Comparison of whole-body equivalent doses from volumetric modulated arc therapy and static intensity-modulated radiotherapy for cervical cancer

目的 比较VMAT和静态IMRT技术在宫颈癌放疗中所致患者全身当量剂量。方法 选取2014年间收治的9例宫颈癌放疗患者, 针对每例患者设计出VMAT和IMRT计划。在进行VMAT和IMRT治疗中,使用热释光剂量计（TLDs）测量每例患者在剑突和眉间位置上的当量剂量Hp（10）,并基于剑突位置上测量的当量剂量估算出患者全身当量剂量。配对t检验二者差异。结果 采用VMAT技术在每例患者剑突和眉间位置上测量的当量剂量均低于IMRT技术。当给予患者50 Gy处方剂量,选取患者剑突位置的平均当量剂量作为代表患者全身当量剂量时,WMAT和IMRT放疗技术所致患者的全身当量剂量分别为364 mSv和538 mSv。结论 VMAT技术比IMRT技术可导致患者更低的全身当量剂量, 可降低辐射诱发癌症发生的危险度。

Objective To compare the whole-body equivalent doses from volumetric modulated arc therapy （VMAT） and static intensity-modulated radiotherapy （IMRT） for patients with cervical cancer. Methods Nine patients with cervical cancer admitted to our hospital in 2014 were included in this study. Both VMAT and IMRT were planned for each patient. Each patient’s personal dose equivalent （Hp （10）） was measured using thermoluminescent dosimeters placed at the xiphoid process and glabella during IMRT and VMAT. The whole-body equivalent doses were estimated based on the results measured at the xiphoid process and compared between the VMAT and IMRT techniques. The paired t test was used for difference analysis. Results The Hp （10） values measured at the xiphoid process and glabella of every patient were lower for VMAT than for IMRT. At a prescribed dose of 50 Gy, if the mean Hp （10） values measured at the xiphoid process were considered to represent the whole-body equivalent doses, the whole-body equivalent doses for VMAT and IMRT were 364 mSv and 538 mSv, respectively. Conclusions VMAT results in a lower whole-body equivalent dose to patients compared with IMRT. The decreased whole-body equivalent dose delivered by VMAT may reduce the likelihood of a radiation-induced secondary malignancy.