Energy spectrum and dose enhancement due to the depth of the Lipiodol position using flattened and unflattened beams
Energy spectrum and dose enhancement due to the depth of the Lipiodol position using flattened and unflattened beams
复制标题
使用平坦和非平坦光束由于碘化油位置的深度而导致的能谱和剂量增强
DOI：
10.1016/j.rpor.2017.12.004
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发表时间：
2018
影响因子：
1.2
通讯作者：
Murakami Y and Nagata Y
中科院分区：
文献类型：
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作者：
Kawahara D;Ozawa S;Saito A;Kimura T;Suzuki T;Tsuneda M;Tanaka S;Hioki K;Nakashima T;Ohno Y;Murakami Y and Nagata Y
目的碘油用于立体定向体部放疗联合经动脉化疗栓塞。在经动脉化疗栓塞中用于肿瘤探查的碘油仍用于立体定向体部放射治疗。在我们之前的研究中，我们报告了碘油与10×无滤过器（FFF）的剂量增强效应。我们研究的目的是评估扁平（FF）和FFF射束由于碘油深度而导致的光子和电子的剂量增强和能谱。本研究使用了来自TrueBeam的6 [[ce：hsp sp=”0.25”/]] MV射束的FF和FFF。碘油（3 [[ce：hsp sp=”0.25”/]]×[[ce：hsp sp=”0.25”/]] 3 [[ce：hsp sp=”0.25”/]]×[[ce：hsp sp=”0.25”/]] 3 [[ce：hsp sp=”0.25”/]] cm 3）位于1、3、5、10、20和30 [[ce：hsp sp=”0.25”/]] cm。结果FF束和FFF束在碘油中心的剂量增强因子分别为6.8%、7.3%、7.6%、7.2%、6.1%和5.7%，而FFF束在碘油中心的剂量增强因子分别为20.6%、22.0%、21.9%、20.0%、12.3%、12.3%和12.3%。在碘油位于水中的深度1、3、5、10、20和30 [[ce：hsp sp=”0.25”/]] cm处，分别为12.1%。此外，光谱结果表明，碘油位于水中的较浅深度存在更多低能光子和电子。由于碘油位置的深度在低能量谱的变化是更明确的与FFF光束比与FF beam.ConclusionsThe当前的研究揭示了DEF和能量谱的变化，由于碘油位置的深度与FF和FFF光束。尽管FF射束可降低碘油位置深度引起的能量依赖性效应，但剂量增强总体较小。为了引起大剂量增强，应使用患者表面到碘油的距离在10 [[ce：hsp sp=”0.25”/]] cm以内的FFF射束。
AimLipiodol was used for stereotactic body radiotherapy combining trans arterial chemoembolization. Lipiodol used for tumour seeking in trans arterial chemoembolization remains in stereotactic body radiation therapy. In our previous study, we reported the dose enhancement effect in Lipiodol with 10× flattening-filter-free (FFF). The objective of our study was to evaluate the dose enhancement and energy spectrum of photons and electrons due to the Lipiodol depth with flattened (FF) and FFF beams.MethodsFF and FFF for 6 [[ce: hsp sp=" 0.25"/]] MV beams from TrueBeam were used in this study. The Lipiodol (3 [[ce: hsp sp=" 0.25"/]]×[[ce: hsp sp=" 0.25"/]] 3 [[ce: hsp sp=" 0.25"/]]×[[ce: hsp sp=" 0.25"/]] 3 [[ce: hsp sp=" 0.25"/]] cm 3) was located at depths of 1, 3, 5, 10, 20, and 30 [[ce: hsp sp=" 0.25"/]] cm in water. The dose enhancement factor (DEF) and the energy fluence were obtained by Monte Carlo calculations of the particle and heavy ion transport code system (PHITS).ResultsThe DEFs at the centre of Lipiodol with the FF beam were 6.8, 7.3, 7.6, 7.2, 6.1, and 5.7% and those with the FFF beam were 20.6, 22.0, 21.9, 20.0, 12.3, and 12.1% at depths of 1, 3, 5, 10, 20, and 30 [[ce: hsp sp=" 0.25"/]] cm, respectively, where Lipiodol was located in water. Moreover, spectrum results showed that more low-energy photons and electrons were present at shallow depth where Lipiodol was located in water. The variation in the low-energy spectrum due to the depth of the Lipiodol position was more explicit with the FFF beam than that with the FF beam.ConclusionsThe current study revealed variations in the DEF and energy spectrum due to the depth of the Lipiodol position with the FF and FFF beams. Although the FF beam could reduce the effect of energy dependence due to the depth of the Lipiodol position, the dose enhancement was overall small. To cause a large dose enhancement, the FFF beam with the distance of the patient surface to Lipiodol within 10 [[ce: hsp sp=" 0.25"/]] cm should be used.