【摘要】 目的:分析和评估一款热塑膜固定底板对调强放射治疗(IMRT)计划三维剂量验证通过率的影响,并对其进行剂量修正。方法:利用Octavius 4D三维剂量验证系统,对60例IMRT计划按照后入射野数占总射野数比值分成6组,分别进行仅有床板和有床板与热塑膜固定底板组合的三维剂量验证,以评估热塑膜固定底板对IMRT三维剂量验证通过率的影响。然后对入射野数占比最大的第6组进行剂量修正,并与修正前的γ通过率进行比较,评估剂量修正的作用。结果:未考虑固定底板时,6组IMRT计划γ通过率分别为:98.00%、96.87%、96.76%、94.82%、95.51%、95.32%;考虑固定底板以后分别为:98.88%、96.46%、95.85%、93.12%、93.22%、89.07%,考虑前后P值分别为0.147、0.534、0.406、0.051、0.030(t=2.566)、0.000(t=5.637),第5组和第6组有统计学差异。对第6组进行固定底板剂量修正以后,γ通过率平均为94.90%,提高5.8%。结论:热塑膜固定底板对IMRT计划三维剂量验证通过率有一定的影响,且当IMRT计划的后入射野数所占总射野数比值越大,影响越大,临床制定计划时有必要对固定底板进行剂量修正。更多还原

【Abstract】 Objective To analyze and evaluate the effect of an immobilization baseplate of thermoplastic film on the passing rate of intensity-modulated radiotherapy(IMRT) three-dimensional(3 D) dosimetric verification, and to modify the dose. Methods Octavius 4 D dosimetric verification system was used for 3 D dosimetric verification. According to the proportion of the number of incident fields to the total number of fields, 60 cases of IMRT plans were divided into 6 group for the 3 D dosimetric verification with couch plate alone or couch plate combined with immobilization baseplate of thermoplastic film so as to evaluate the effect of immobilization baseplate of thermoplastic film on the passing rate of IMRT 3 D dosimetric verification. Dose modification was carried out in the 6 th group which had the highest proportion of the number of incidence fields in all groups, and then the passing rate was compared with that before dose modification for evaluating the role of dose modification. Results Without considering immobilization baseplate, the gamma passing rates of 6 groups of IMRT plans were 98.00%, 96.87%, 96.76%, 94.82%, 95.51%and 95.32%, respectively; and after that immobilization baseplate was considered, the gamma passing rates were 98.88%, 96.46%,95.85%, 93.12%, 93.22% and 89.07%, respectively. The corresponding P values were 0.147, 0.534, 0.406, 0.051, 0.030(t=2.566)and 0.000(t=5.637), respectively, and statistical differences were only found in the 5 th and 6 th groups. After the dose modification for immobilization baseplate in the 6 th group, the average gamma passing was 94.90%, increased by 5.8%. Conclusion Immobilization baseplate of thermoplastic film has a certain effect on the passing rate of IMRT 3 D dosimetric verification, and the larger proportion of the number of incident fields in IMRT plan is, the greater effect is. It is necessary to modify the dose of immobilization baseplate when making clinical plans.更多还原