Gel dosimetry for brachytherapy dose delivery validation

现代放射治疗通过技术的发展取得了进步，以更好地塑造肿瘤体积的辐射剂量，同时最大限度地减少对周围正常组织的不良剂量影响。在近距离放射治疗（希腊语：近距离治疗）中，放射源在机器人控制下被放置到肿瘤中。在辐射源附近放置剂量探测器会影响相邻区域的剂量。因此，近距离放射治疗中的剂量传递验证通常基于非常简单的几何形状的质量保证，这些几何形状不像患者治疗过程中遇到的那么复杂。一种有前途的剂量测量技术是凝胶剂量测定法，它基于成像特殊的凝胶系统，当受到照射时会发生变化。这些变化可以用我们实验室可用的各种技术成像，并提供剂量的空间分布。凝胶模拟组织，因此测量的剂量对应于患者的剂量。因此，剂量测量更加准确，我们可以在治疗开始前验证给定患者的计划输送。我们建议：i）测试当前凝胶制剂在近距离放射治疗剂量测定中的有效性和缺点，并创建、表征和测试专门为近距离放射治疗应用设计的新制剂; ii）开发针对近距离放射治疗剂量输送的标准协议和体模;以及，iii）开发软件以评估和比较凝胶测量的剂量与使用常规工具的测量以及与计划的剂量递送。计划的递送的测试在使用X射线机的其他放射治疗递送中每天进行，但尚未用于近距离放射治疗。我们将是第一个为近距离放射治疗开发患者特异性剂量输送验证的公司。

Modern radiation therapy has advanced through the development of techniques to bettershape radiation dose to tumour volumes while minimizing adverse dose effects to surroundingnormal tissue. In brachytherapy (Greek: near therapy) radiation sources are placed into thetumour under robotic control. Placing a dose detector near the radiation source affects dosein adjacent regions. For this reason, dose delivery validation in brachytherapy is usuallybased on quality assurance of very simple geometries that are not as complex as thoseclinically encountered during patient treatments.A promising technique for dose measurement is gel dosimetry which is based on imagingspecial gel systems which change when irradiated. The changes can be imaged with varioustechniques available to our laboratory and provide the spatial distribution of the dose. Thegels mimic tissue and so the dose measured corresponds to the dose to a patient. As a result,dose measurement is more accurate and we can validate a planned delivery for a givenpatient before treatment starts.We propose to: i) test current gel formulations for their effectiveness and shortcomings inbrachytherapy dosimetry and create, characterize and test new formulations designedspecifically for brachytherapy applications; ii) develop standard protocols and phantomsspecific to brachytherapy dose delivery; and, iii) develop software to evaluate and comparegel-measured doses to measurements using conventional tools and to planned dose delivery.Testing of planned delivery is performed daily in other radiation therapy delivery with x-raymachines but is not yet available for brachytherapy. We will be the first to develop patientspecific dose delivery validation for brachytherapy.