Dosimetry of a novel converging X-ray source for kilovoltage radiotherapy.
Dosimetry of a novel converging X-ray source for kilovoltage radiotherapy.
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DOI：
10.1002/mp.15167
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发表时间：
2021-10
期刊：
影响因子：
3.8
通讯作者：
Boyd D
中科院分区：
文献类型：
--
作者：
Stalbaum T;Partain L;Weil MD;Kim J;Han JY;Plies MJ;Chen H;Ziskin V;Bazalova-Carter M;Song S;Rand R;Boyd D
这项工作的目的是评估一种新型的千伏X射线源的体模剂量学，该源采用固定的钨阳极和线性扫描的电子束。该源利用会聚的X射线准直和垂直的机械旋转来在大范围内分布地表通量。在这项研究中，这是一种潜在的解决方案，以解决预期的千伏放射治疗的快速衰减限制。这样做的目的是为了未来临床开发一种替代兆伏(MV)直线加速器系统的低成本放射治疗方案。采用辐射变色胶片对直线会聚放射治疗系统(LCRS)的KV型X射线源进行剂量测量。该光源利用电荷粒子光学技术，使电子束在超高真空不锈钢腔内沿着静止的、反射的钨靶磁偏转和聚焦。产生的X射线被准直成跨越大平面角的会聚光束，并在系统等中心会聚。在这项研究中，放射变色薄膜剂量测定是在140和145kVp下进行的，指定的计划治疗体积(PTV)直径为4厘米。用丙烯酸酯体模测量了静止和旋转给药的剂量分布。在平行于源X射线窗口的不同深度的平面以及在龙门旋转的平面上对胶片剂量学进行了评估。在140和145kVp下，使用深度为4 cm的准直平方野，病变与皮肤的剂量比显示出随着来自不同相对源位置的额外光束的增加而改善，其中不同的光束聚焦在相同的等中心，并且不在体模表面重叠。用4束投射光束只能达到1：1Dmax与表面的比例，但用12束投射光束，在丙烯酸模体中聚焦在相同的7.8 cm等中心深度时，该比例提高到4：1。在进行的测试中，获得了以下Dmax与表面的比率：从一个入射束固定输送的病变与皮肤的比率为0.4：1，两个光束的病变与皮肤的比率为0.71：1，四个光束的病变与皮肤比率为1.07：1，12个光束的病变与皮肤比率为4：1。对静态和旋转剂量学剂量-深度分布进行了评估。此外，旋转剂量学测量的病例更类似于临床情景，其中等中心位于偏离中心的模拟病变。结果表明，通过沿LCRS的垂直机械源旋转沿宽会聚光束分布表面通量，千伏弧光治疗可能会改善剂量-深度。当达到多个分离的光束的阈值时，该系统向大的表面积提供可容忍的剂量。辐射变色胶片数据支持了LCRS-KV放射治疗系统设计方案的可行性。
The objective of this work was to evaluate phantom dosimetry of a novel kilovoltage (kV) x-ray source, which employs a stationary tungsten anode and a linearly swept scanning electron-beam. The source utilizes converging x-ray collimation along with orthogonal mechanical rotation to distribute surface flux over large area. In this study, this was investigated as a potential solution to fast-falloff limitations expected with kV radiotherapy. This was done with the aim of future clinical development of a lower-cost radiotherapy alternative to megavoltage (MV) linac systems. Radiochromic film was employed for dosimetry on the kV x-ray source of the Linear-Converging Radiotherapy System (LCRS). The source utilizes charge particle optics to magnetically deflect and focus an electron beam along a stationary, reflection tungsten target in an ultra-high-vacuum stainless-steel chamber. Resulting x-rays were collimated into converging beamlets that span a large planar angle and converge at the system isocenter. In this study, radiochromic film dosimetry was done at 140 and 145 kVp for a designated planning treatment volume (PTV) of 4-cm diameter. An acrylic phantom was employed for dose distribution measurements of stationary and rotational delivery. Film dosimetry was evaluated in planes parallel to the source x-ray window at various depths, as well as in the plane of gantry rotation. At 140 and 145 kVp and using a collimated 4-cm square field at depth, lesion-to-skin dose ratio was shown to improve with additional beams from different relative source positions, where the different beams are focused at the same isocenter and do not overlap at the phantom surface. It was only possible to achieve a 1:1 Dmax-to-surface ratio with four delivery beams, but the ratio improved to 4:1 with 12 beams, focused at the same isocenter depth of 7.8 cm in an acrylic phantom. For the tests conducted, the following Dmax-to-surface ratios were obtained: 0.4:1 lesion-to-skin ratio for stationary delivery from one entry beam, 0.71:1 lesion-to-skin ratio was obtained for two beams, 1.07:1 ratio for four beams, and 4:1 for 12 beams. Dose-depth profiles were evaluated for stationary and rotational dosimetry. Additionally, rotational dosimetry was measured for a case more analogous to a clinical scenario, where the isocenter was located at an off-center simulated lesion. The results demonstrate potential dose-depth improvements with kV arc therapy by distributing the surface flux with a wide converging beam along with perpendicular mechanical source rotation of the LCRS. The system delivered tolerable dose to a large surface area when a threshold of multiple, separated beams was reached. The radiochromic film data supports the feasibility of the construct of the LCRS kV radiotherapy system design.
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3.8
作者：
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通讯作者：
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DOI：
10.1016/j.ijrobp.2011.12.042
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2012-10-01
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影响因子：
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