Product Development of Intensity Modulation for Bolus Electron Conformal Therapy

项目摘要/摘要 使用6-20 MeV束流的电子束治疗(EBT)提供了有效的浅表放射治疗 癌症(深度&lt；6厘米)。多达20%的放射治疗患者(美国每年的为166,000人)有资格 电子治疗的一部分，使其成为第二大最常用的外照射 情态。多达10%的电子患者(每年为16,600人)可以从团注电子中受益 适形治疗(ECT)，一种使剂量分布(远端90%等剂量表面)符合 靶向肿瘤体积，同时保护周围健康组织免受急性和长期不良影响 辐射的影响，与该机构提高癌症治疗质量的使命相一致。目前， 由于剂量不均匀(高达30%)，放射肿瘤学家在团注ECT方面的使用受到限制 靶向肿瘤体积是由于不规则的近端团块表面的多次库仑散射造成的。 本申请一期提出要研究开发电子强度调制技术 (计划软件和交付设备)，当与现有的团注ECT技术集成时，可以 消除剂量异质性问题，即提供更均匀的剂量分布(10%剂量分布) 到靶向癌症体积。建议的产品，强度调节剂ECT的可用性，应该 不仅极大地改进了目前使用电子放射治疗(团注ECT或 否则)，但在某些情况下提供了对其他辐射形式(例如体积辐射)的改进的替代 弧光疗法或调强放射疗法)通过(1)降低继发性癌症的机会，(2) 同样高的癌症控制率，以及(3)同样低的急性正常组织并发症的机会。 建议的传输技术是强度调制板，它由以下矩阵组成 嵌入在低密度板中的小直径圆柱形岛块， 准直镶件。强度调制的大小与覆盖的束流面积的比例有关 在一个小的覆盖区域的岛屿区块旁边。通过适当地改变这些部件的直径和/或间隔 岛屿区块，电子在空气中的散射应导致患者身上平稳变化的强度图案 和/或在使用推注ECT时恢复癌症靶区内的剂量均匀度的推注。 第一阶段的目标是通过(1)将强度调制合并到 现有的BolusECT软件产品，包括一种将强度模式“分割”成 适当的岛块矩阵，(2)验证对岛块建模的规划软件 为选定的患者部位产生预期结果，以及(3)验证计划强度的交付 通过证明已交付(测量)和计划之间的一致性来调制Bolus-ECT光束 (计算)水中的剂量分布。

Project Summary/Abstract Electron beam therapy (EBT) using 6-20 MeV beams provides effective radiation treatment for superficial cancers (depth<6 cm). As many as 20% of radiotherapy patients (166,000 in USA annually) are eligible for electron therapy for some portion of their treatment, making it the second most used external beam modality. As many as 10% of these electron patients (16,600 annually) could benefit from bolus electron conformal therapy (ECT), a technique conforming the dose distribution (distal 90% isodose surface) to the targeted cancer volume while protecting surrounding healthy tissue from acute and long-term adverse effects of radiation, aligning with the agency mission to improve cancer treatment quality. Currently, radiation oncologists are limited in the use of bolus ECT because of dose heterogeneity (as great as 30%) in the targeted cancer volume due to multiple Coulomb scattering from the irregular proximal bolus surface. This Phase I application proposes to research and develop electron intensity modulation technology (planning software and delivery device), which when integrated with existing bolus ECT technology, can eliminate the dose heterogeneity problem, i.e., deliver a more uniform dose distribution (10% dose spread) to the targeted cancer volume. Availability of the proposed product, intensity modulated bolus ECT, should not only greatly improve current treatments of superficial cancers using electron radiotherapy (bolus ECT or otherwise), but in some cases provide an improved alternative to other radiation modalities (e.g. volumetric arc therapy or intensity modulated radio-therapy) by having (1) decreased chance of secondary cancers, (2) equally high chance of cancer control, and (3) equally low chance of acute normal tissue complications. The proposed delivery technology is an intensity modulator plate, which consists of a matrix of small-diameter, cylindrical island blocks imbedded in a low-density slab attached to the beam-defining, collimating insert. The magnitude of the intensity modulation is related to the fraction of beam area covered by the island blocks in a small overlying region. By properly varying the diameter and/or separation of these island blocks, electron scatter in air should result in a smoothly varying intensity pattern on the patient and/or bolus that restores the dose uniformity in the cancer target volume when using bolus ECT. Phase I goals will be to demonstrate proof of principle by (1) incorporating intensity modulation into the existing BolusECT software product, including a method for ‘segmenting’ the intensity pattern into an appropriate matrix of island blocks, (2) validating that the planning software modeling the island blocks produces expected results for select patient sites, and (3) validating delivery of the planned intensity modulated BolusECT beams by demonstrating agreement between delivered (measured) and planned (calculated) dose distributions in water.