Grant: Collaborative Health Research Projects (NSERC partnered)

Modern radiation therapy has advanced through the development of techniques to better shape radiation dose to tumour volumes while minimizing adverse dose effects to surrounding normal tissue. In brachytherapy (Greek: near therapy) radiation sources are placed into the tumour under robotic control. Placing a dose detector near the radiation source affects dose in adjacent regions. For this reason, dose delivery validation in brachytherapy is usually based on quality assurance of very simple geometries that are not as complex as those clinically encountered during patient treatments. A promising technique for dose measurement is gel dosimetry which is based on imaging special gel systems which change when irradiated. The changes can be imaged with various techniques available to our laboratory and provide the spatial distribution of the dose. The gels 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 given patient before treatment starts. We propose to: i) test current gel formulations for their effectiveness and shortcomings in brachytherapy dosimetry and create, characterize and test new formulations designed specifically for brachytherapy applications; ii) develop standard protocols and phantoms specific to brachytherapy dose delivery; and, iii) develop software to evaluate and compare gel-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-ray machines but is not yet available for brachytherapy. We will be the first to develop patient specific dose delivery validation for brachytherapy.