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，以更好地确定对肿瘤体积的辐射剂量，同时尽量减少对周围正常组织的不良剂量影响。在近距离治疗中，辐射源在机器人的控制下被放置在肿瘤中。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期间临床遇到的那样复杂。凝胶剂量法是一种很有前途的剂量测量技术，它基于对特殊凝胶系统的成像，这些凝胶系统在辐照时发生变化。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，因此测量的剂量与患者的剂量相对应。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交付。我们建议：i)测试当前凝胶制剂在近距离治疗剂量学中的有效性和缺点，并创建、表征和测试专为近距离治疗应用而设计的新制剂；Ii)制定近距离放疗剂量递送的标准方案和模型；iii)开发软件，以评估和比较使用常规工具测量的剂量和计划给药剂量。在其他放射治疗中，每日使用x光机进行计划递送测试，但尚未用于近距离治疗。我们将率先开发近距离放射治疗的患者特异性剂量传递验证。

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.