肺转移瘤SBRT放射治疗技术中Tomo计划同BrainLab计划的剂量学研究(英文)

Dosimetry Study for Lung Metastases in SBRT Technology Using Tomo Planning System versus BrainLab Planning System

【目的】对比肺转移瘤立体定向放射治疗(Stereotactic Body radiation therapy,SBRT)使用Tomo技术和BrainLab技术的剂量学差异。【方法】分别选取单一肺转移瘤、两个肺转移瘤、三个肺转移瘤和四个肺转移瘤病例各一例,PTV体积为2.89±1.15 cm3。使用Tomo和BrainLab计划系统分别进行计划设计,每次剂量5 Gy,总剂量50 Gy并覆盖95%PTV体积的处方剂量,比较治疗计划的脊髓、双肺和其它正常器官的DVH曲线、靶区的CI和HI指标。【结果】Tomo计划设计的靶区剂量的适型指数CI=0.687±0.075、均匀指数HI=1.0314±0.0700,BrainLab计划设计的靶区剂量适型指数CI=0.571±0.042、均匀指数HI=1.0764±0.1241,两组HI和CI进行独立样本t检验,P值均小于0.001具有统计学意义,Tomo计划的靶区CI和HI指标均优于Bran Lab计划。BrainLab系统中的脊髓的低剂量要高于Tomo计划,而两组正常器官和双肺的剂量无明显的差异,肺的V20均小于10%。【结论】对于最长径小于4 cm的小体积的肺转移瘤,应该优先使用Tomo技术。

【Objective】To compare and contrast the dosimetry between Tomo planning and Brain Lab planning for lung metastases in stereotactic body radiation therapy（SBRT）.【Methods】Four Patients with one,two,three and four metastases were selected.The PTV is 2.89 ± 1.15 cm3. Two plannings with total dose of 50 Gy to cover 95% of PTV,5 Gy/Fraction and 10 fractions were designed using Tomo planning system and Brain Lab planning system respectively. The DVH curves of spinal cord,both lungs and normal tissue were compared. The conformity index andhomogeneityindex were analyzed as well.【Results】The homogeneity index（HI）and conformity index（CI）of the targets in Tomo planning system were 1.0314 ± 0.0700 and 0.687 ± 0.075,respectively. In Brain Lab planning system the HI and CI of the targets were 1.0764 ± 0.1241 and 0.571 ± 0.042,respectively. To HI the P value in T test was less than 0.01 and the HI was better in Tomo than Brain Lab and so was CI. The dose to spinal cord was higher in Brain Lab planning system than that in Tomo. The dose to nomal tissue and both lungs were not different in the two planning systems and V20 of lung is as small as 10%.【Conclusions】For small volume lung metastases which longest diameter were less than 4 cm,the tomotherapy should be better choice.