Merging Orthovoltage X-Ray Minibeams spare the proximal tissues while producing a solid beam at the target
Merging Orthovoltage X-Ray Minibeams spare the proximal tissues while producing a solid beam at the target
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DOI：
10.1038/s41598-018-37733-x
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发表时间：
2019-02-04
影响因子：
4.6
通讯作者：
Eley, John G.
中科院分区：
文献类型：
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作者：
Dilmanian, F. Avraham;Krishnan, Sunil;Eley, John G.
脑肿瘤的常规放射治疗通常会产生认知缺陷，特别是在儿童中。我们研究了合并正交电压X射线微束（OXM）的潜在功效。它将光束分割成平行的、薄的（类似于0.3 mm）平面光束阵列，称为微型光束，这是同步加速器X射线实验中已知的，用于备用组织。此外，OXM阵列的轻微发散使得各个小光束逐渐变宽，从而在给定的组织深度处与它们的邻居合并以产生固体光束。这样，包括大脑皮层在内的近端组织就可以幸免。在这里，我们提出的实验结果与辐射变色薄膜表征方法的剂量学。此外，我们提出了我们的Monte Carlo模拟结果的物理吸收剂量，和一阶生物模型来预测组织耐受性。特别是，220-kVp的正电压束提供了比6-MV X射线束尖锐5倍的侧向半影。该方法可以在弧形扫描中实现，弧形扫描可以包括容积调制弧形治疗（VMAT）。最后，OXM的低光束能量使其成为使用碘或金纳米粒子等造影剂进行肿瘤剂量增强的理想选择，其低成本、便携性和小房间屏蔽要求使其成为中低收入国家的理想选择。
Conventional radiation therapy of brain tumors often produces cognitive deficits, particularly in children. We investigated the potential efficacy of merging Orthovoltage X-ray Minibeams (OXM). It segments the beam into an array of parallel, thin (similar to 0.3 mm), planar beams, called minibeams, which are known from synchrotron x-ray experiments to spare tissues. Furthermore, the slight divergence of the OXM array make the individual minibeams gradually broaden, thus merging with their neighbors at a given tissue depth to produce a solid beam. In this way the proximal tissues, including the cerebral cortex, can be spared. Here we present experimental results with radiochromic films to characterize the method's dosimetry. Furthermore, we present our Monte Carlo simulation results for physical absorbed dose, and a first-order biologic model to predict tissue tolerance. In particular, a 220-kVp orthovoltage beam provides a 5-fold sharper lateral penumbra than a 6-MV x-ray beam. The method can be implemented in arc-scan, which may include volumetric-modulated arc therapy (VMAT). Finally, OXM's low beam energy makes it ideal for tumor-dose enhancement with contrast agents such as iodine or gold nanoparticles, and its low cost, portability, and small room-shielding requirements make it ideal for use in the low-and-middle-income countries.