Gore J C, Ranade M, Maryañski M J, Schulz R J
Department of Diagnostic Radiology, Yale University, New Haven, CT 06510, USA.
Phys Med Biol. 1996 Dec;41(12):2695-704. doi: 10.1088/0031-9155/41/12/009.
A new method of dosimetry of ionizing radiations has been developed that makes use of tissue-equivalent polymer gels which are capable of recording three-dimensional dose distributions. The dosimetric data stored within the gels are measured using optical tomographic densitometry. The dose-response mechanism relies on the production of light scattering microparticles which result from the polymerization of acrylic comonomers dispersed in the gel. The attenuation of a collimated light beam caused by scattering in the irradiated optically turbid medium is directly related to the radiation dose over the range 0-10 Gy. An optical scanner has been developed which incorporates an He-Ne laser, photodiode detectors, and a rotating gel platform. Using mirrors mounted on a translating stage, the laser beam scans across the gel between each incremental rotation of the platform. Using the set of optical density projections obtained, a cross sectional image of the radiation field is then reconstructed. Doses in the range 0-10 Gy can be measured to better than 5% accuracy with a spatial resolution approximately 2 mm using the current prototype scanner. This method can be used for the determination of three-dimensional dose distributions in irradiated gels, including measurements of the complex distributions produced by multi-leaf collimators, dynamic wedge and stereotactic treatments, and for quality assurance procedures.
一种新的电离辐射剂量测定方法已被开发出来，该方法利用了能够记录三维剂量分布的组织等效聚合物凝胶。凝胶中存储的剂量数据使用光学断层密度计进行测量。剂量响应机制依赖于由分散在凝胶中的丙烯酸共聚单体聚合产生的光散射微粒。在受辐照的光学浑浊介质中，由散射引起的准直光束的衰减与0-10 Gy范围内的辐射剂量直接相关。已开发出一种光学扫描仪，它包含氦氖激光器、光电二极管探测器和一个旋转凝胶平台。通过安装在平移台上的镜子，激光束在平台每次增量旋转之间扫描凝胶。利用获得的一组光密度投影，然后重建辐射场的横截面图像。使用当前的原型扫描仪，0-10 Gy范围内的剂量测量精度可优于5%，空间分辨率约为2毫米。该方法可用于确定辐照凝胶中的三维剂量分布，包括测量由多叶准直器、动态楔形和立体定向治疗产生的复杂分布，以及用于质量保证程序。
