Feasibility study of a dosimeter for in vivo measurements of the absolute dose delivered in high dose rate brachytherapy

Radiation doses delivered to the patient during high dose rate brachytherapy treatments are susceptible to many inaccuracies and may not accurately match the planned doses. In vivo dosimetry is a reliable solution to compare planned and delivered dose distributions, representing therefore a valid tool to increment treatment accuracy. In this study, dosimetric catheters were developed in laboratory and optimized to be used for in vivo measurements of high dose rate brachytherapy treatments. Measurements were performed in different irradiation configurations with ad hoc developed phantoms. Preliminary measurements of dose distributions achieved with a 6MV linear accelerator showed a high linear response of the dosimetric catheters with the delivered dose. Moreover, measurements performed with the brachytherapy high dose rate remote afterloading device provided with an Ir-192 radioactive source showed high accordance between planned dose and dose measured with the dosimetric catheters at 1mm3 spatial resolution. Results show that dosimetric catheters are valid candidates for performing in-vivo linear dosimetry in HDR brachytherapy, representing an innovative tool that could help to significantly increase safety and accuracy in the brachytherapy treatments delivery. Eventually, these improvements might conduce to the best achievable therapeutic results, that is higher survival and recovery rates of the patients.