Field size dependence of the output factor in passively scattered proton therapy: Influence of range, modulation, air gap, and machine settings
Field size dependence of the output factor in passively scattered proton therapy: Influence of range, modulation, air gap, and machine settings
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DOI：
10.1118/1.3152111
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发表时间：
2009-07-01
期刊：
影响因子：
3.8
通讯作者：
Bussiere, M. R.
中科院分区：
文献类型：
--
作者：
Daartz, J.;Engelsman, M.;Bussiere, M. R.
在弗朗西斯H。Burr质子治疗中心现场特定输出因子（即，每个监视器单元的剂量）对所有射束线（两个机架、固定立体定向和固定眼睛射束线）进行建模。作者评价了小野剂量计算和输出模型的准确性。在我们的三个光束线中进行水模中的测量，量化输出因子对各种质子范围的场大小的依赖性。研究了喷嘴尺寸、气隙、调制方式和第二散射体等因素的影响。字段大小对输出的影响在很大程度上取决于感兴趣的深度。气隙对小磁场输出有显著影响。如果在没有定制硬件的情况下对输出进行建模或测量，则需要输出的字段大小特定校正因子。的输出被证明是场的大小依赖于即使是大的字段，表示超出带电粒子的横向散射引起的不平衡的影响。
At the Francis H. Burr Proton Therapy Center field specific output factors (i.e., dose per monitor unit) for patient treatments were modeled for all beamlines (two gantries, fixed stereotactic, and fixed eye beamline). The authors evaluated the accuracy of dose calculation and output model for small fields. Measurements in a water phantom were performed in three of our beamlines quantifying the dependency of the output factor on the field size for a variety of proton ranges. The influence of snout size, air gap, modulation, and second scatterer was investigated. The impact of field size on output depends strongly on the depth of interest. The air gap has a notable influence on small field outputs. A field size specific correction factor to the output is necessary if the latter was modeled or measured without the custom hardware in place. The output was shown to be field size dependent even for large fields, indicating an effect beyond charged particle disequilibrium caused by lateral scatter.