OPTICAL TOMOGRAPHY OF POLYMER GELS FOR 3D DOSIMETRY

本项目旨在开发一种新型的组织等效凝胶剂量仪。 电离辐射，它能够产生高度分辨率和 利用光学方法获得精确的三维剂量分布数据 断层扫描密度计量学。剂量反应机制依赖于 现场凝胶中瑞利散射微粒的产生 辐射吸收，其中分散在凝胶中的丙烯酸共聚单体是 聚合的。准直光通过时的吸收和散射 通过光学混浊的介质产生光的净衰减 可测量且与剂量直接相关的强度。 光密度投射到不同区域的测量 方向可以用来重建辐射剂量的分布 在凝胶里。1Gy量级的剂量可以用空间辐射测量 分辨率&lt；1 mm。在第一阶段，凝胶的基本光学性质为 已被研究并使用单一激光的光学扫描仪原型 构建了光束和扫描光电二极管，并成功地用于 创建准确的2D剂量图。第二阶段的目标是重新设计 光学层析成像设备，以便合理地执行3D扫描 时代，进一步开发重建和图像分析软件 扫描仪，并进一步评估和开发 针对其光学性能进行了优化的聚合物凝胶。后者将 要求进行研究，以更好地了解影响 聚合物凝胶的光密度-剂量响应。有重要的 使用这种更简单的光学方法读取剂量的优点 由凝胶存储的分布与磁共振成像相比，这是唯一 另类选择。聚合物凝胶光学扫描仪系统将发现 在放射治疗实践中广泛使用，用于三维测量 同质和拟人模体，计算机化的确认 治疗计划和质量保证程序。 拟议的商业应用：大约125次验收测试 新的高能X光机需要测量6到 12个剂量分布，使用约1200个凝胶。质量保证 现有的2500台直线加速器的程序可能需要10,000台 聚合物凝胶。近距离放射治疗和实验应用可以解释 再买2,000个凝胶。以每种凝胶300美元的价格，凝胶的初始年销售额在 预计将超过300万美元。扫描仪销售额(每年25台， 每人60,000美元)将增加150万美元。

This project aims to develop a novel, tissue-equivalent gel-dosimeter of ionizing radiation, which is capable of producing highly-resolved and accurate data on three dimensional dose distributions using optical tomographic densitometry. The dose-response mechanism relies on the production of Rayleigh scattering micro-particles in the gel at the site of radiation absorption, where acrylic comonomers dispersed in the gel are polymerized. Absorption and scattering of collimated light passing through the optically turbid medium produces a net attenuation of light intensity that can be measured and is directly related to the dose. Measurements of the projections of the optical density into different directions can be used to reconstruct the distribution of radiation doses within the gel. Doses of the order of 1 Gy can be measured with a spatial resolution <1mm. In Phase 1, basic optical properties of the gel have been investigated and a prototype optical scanner using a single laser beam and scanning photodiode was constructed and used successfully to create accurate 2D dose maps. The goals of Phase 2 are to reengineer the optical tomography apparatus in order to perform 3D scanning in reasonable times, to further develop the reconstruction and image analysis software of the scanner, and to further evaluate and develop formulations of polymer gel optimized for their optical properties. The latter will require studies designed to better understand the factors that affect the optical density - dose response of polymer gels. There are significant advantages to the use of this simpler optical method of reading the dose distribution stored by the gel compared to MR imaging, which is the only alternative. The polymer gel - optical scanner system will find widespread use in radiation therapy practice, for 3D measurements in homogeneous and anthropomorphic phantoms, confirmation of computerized treatment planning and in quality assurance procedures. PROPOSED COMMERCIAL APPLICATION: Acceptance testing of approximately 125 new high energy X-ray machines requires the measurement of between 6 and 12 dose distributions, using about 1,200 gels. Quality assurance procedures for the existing 2,500 linear accelerators could require 10,000 polymer-gels. Brachytherapy and experimental applications could account for 2,000 more gels. At $300 per gel, initial annual sales of gels in excess of $3 Million are anticipated. Scanner sales (25 per year at $60,000 each) would add $l.5 Million to this.