The dosimetric enhancement of GRID profiles using an external collimator in pencil beam scanning proton therapy.
The dosimetric enhancement of GRID profiles using an external collimator in pencil beam scanning proton therapy.
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使用铅笔梁扫描质子治疗中的外部准直仪对网格曲线的剂量计增强。
DOI：
10.1002/mp.15523
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发表时间：
2022-04
期刊：
影响因子：
3.8
通讯作者：
Hyer, Daniel E.
中科院分区：
文献类型：
--
作者：
Smith, Blake R.;Nelson, Nicholas P.;Geoghegan, Theodore J.;Patwardhan, Kaustubh A.;Hill, Patrick M.;Yu, Jen;Gutierrez, Alonso N.;Allen, Bryan G.;Hyer, Daniel E.
空间分割（GRID）放射治疗提供的放射生物学益处与质子治疗的剂量学优势很好地结合在一起。受铅笔束扫描（PBS）中出现的能量层特定准直器的启发，这项工作研究了如何优化光斑间距和准直，以最大限度地提高GRID治疗的治疗效果，同时展示了在商业光束线内集成动态准直系统（DCS），以提供GRID治疗和实验基准蒙特卡罗计算方法。使用安装在IBA专用喷嘴系统的喷嘴上的临床DCS原型对GRID剖面进行了实验基准测试。测量了未准直和栅格准直光束的积分深度剂量曲线和横向分布。通过在指定的均匀网格内放置光束并对光束进行加权来模拟准直GRID剂量分布库，以获得相当于开放场递送的体积平均肿瘤细胞存活率。然后在一定范围的光斑间距和准直宽度范围内估计GRID分布所提供的健康组织节约，然后根据肿瘤细胞系的放射敏感性和PBS系统的标称光斑大小对其进行优化。这是通过使用经过验证的IBA通用和专用喷嘴模型来完成的。实测剖面与模拟剖面非常吻合。当使用1%/1 mm伽玛标准分析时，IDDs匹配度高于98.7%，在布拉格峰附近观察到一些较小的偏差，较高的束流能量。用蒙特卡罗方法预测的侧向剖面分布与实测剖面吻合较好；采用3%/ 2mm标准检测的所有深度剖面的伽马通过率均达到95%或更高。额外的准直被证明可以通过锐化光束的侧面半影来改善PBS GRID治疗，但在增强GRID传输的谷峰比和剂量-体积效应之间产生了权衡。最佳准直宽度和光斑间距随肿瘤细胞放射敏感性、剂量和光斑大小的变化而变化。一般来说，在特定情况下，小于2.0 cm的光斑间距和小于1.0 cm的准直可以提供更好的剂量分布。使用不同准直尺寸和光斑间距定制GRID剂量分布的能力是一个有用的优势，特别是在最大限度地提高整体治疗效益方面。在这方面，DCS的能力，也许还有其他动态准直器，可以用来加强全球资源数据库的处理。用蒙特卡罗方法计算的物理剂量模型在水中进行了实验基准测试，发现可以准确预测未准直和dcs准直GRID剖面的剂量分布。
The radiobiological benefits afforded by spatially fractionated (GRID) radiation therapy pairs well with the dosimetric advantages of proton therapy. Inspired by the emergence of energy-layer specific collimators in pencil beam scanning (PBS), this work investigates how the spot spacing and collimation can be optimized to maximize the therapeutic gains of a GRID treatment while demonstrating the integration of a dynamic collimation system (DCS) within a commercial beam line to deliver GRID treatments and experimentally benchmark Monte Carlo calculation methods. GRID profiles were experimentally benchmarked using a clinical DCS prototype that was mounted to the nozzle of the IBA Dedicated Nozzle system. Integral depth dose (IDD) curves and lateral profiles were measured for uncollimated and GRID-collimated beamlets. A library of collimated GRID dose distributions were simulated by placing beamlets within a specified uniform grid and weighting the beamlets to achieve a volume-averaged tumor cell survival equivalent to an open field delivery. The healthy tissue sparing afforded by the GRID distribution was then estimated across a range of spot spacings and collimation widths, which were later optimized based on the radiosensitivity of the tumor cell line and the nominal spot size of the PBS system. This was accomplished by using validated models of the IBA Universal and Dedicated nozzles. Excellent agreement was observed between the measured and simulated profiles. The IDDs matched above 98.7% when analyzed using a 1%/1 mm gamma criteria with some minor deviation observed near the Bragg peak for higher beamlet energies. Lateral profile distributions predicted using Monte Carlo methods agreed well with the measured profiles; a gamma passing rate of 95% or higher was observed for all in-depth profiles examined using a 3%/2 mm criteria. Additional collimation was shown to improve PBS GRID treatments by sharpening the lateral penumbra of the beamlets but creates a tradeoff between enhancing the valley-to-peak ratio of the GRID delivery and the dose-volume effect. The optimal collimation width and spot spacing changed as a function of the tumor cell radiosensitivity, dose, and spot size. In general, a spot spacing below 2.0 cm with a collimation less than 1.0 cm provided a superior dose distribution among the specific cases studied. The ability to customize a GRID dose distribution using different collimation sizes and spot spacings is a useful advantage, especially to maximize the overall therapeutic benefit. In this regard, the capabilities of the DCS, and perhaps alternative dynamic collimators, can be used to enhance GRID treatments. Physical dose models calculated using Monte Carlo methods were experimentally benchmarked in water and were found to accurately predict the respective dose distributions of uncollimated and DCS-collimated GRID profiles.
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影响因子：
8
作者：
Joensson, G.;Dahl, C.;Borg, A.
通讯作者：
Borg, A.
影响因子：
2.3
作者：
Duriseti S;Kavanaugh J;Goddu S;Price A;Knutson N;Reynoso F;Michalski J;Mutic S;Robinson C;Spraker MB
通讯作者：
Spraker MB
影响因子：
64.8
作者：
Ghandi, Mahmoud;Huang, Franklin W.;Sellers, William R.
通讯作者：
Sellers, William R.
DOI：
10.1016/j.ijrobp.2003.12.031
发表时间：
2004-05-01
影响因子：
7
作者：
Bodey, RK;Evans, PM;Flux, GD
通讯作者：
Flux, GD
影响因子：
3.8
作者：
Gao, M.;Mohiuddin, M. M.;Pankuch, M.
通讯作者：
Pankuch, M.