Wireless In-Vivo Dosimetry of High Dose Rate Brachytherapy for Prostate Cancer using MOSkin Detectors

High Dose Rate brachytherapy is an effective treatment modality for prostate cancer due to the radio-sensitivity of the tumour and short treatment time. This procedure has strong radiation concentration and a steep dose gradient but no acceptable dose verification method to ensure prescribed dose is delivered to minimise damage to tumour-adjacent organs. With radiation emitted directly into the tumour, the most effective monitoring method is in-vivo dosimetry. A new MOSkinTM readout system, OneTouch, has been developed to provide real time dosimetric readouts and temperature variation compensation during in-vivo dosimetry. Through the additional of detectors to the rectal ultrasound probes used during brachytherapy, dosimetric and anatomical data can be transmitted. Two generations of MOSkinTM detectors were analysed through angular and sensitivity testing; the circular gate version proved superior normalised angular dose response of ±1.5% and sensitivity drift of -8.41±0.67%, compared to -28.24±1.19% with the parallel gate design. MOSkinTM detectors are an accurate in-vivo dosimeter, with normalised agreement to the treatment plan of 1.06±0.1 compared to radiochromic film normalised agreement of 1.10±0.01. The OneTouch and MOSkinTM system proved clinically viable and will further improve the safety of prostate cancer treatment through HDR brachytherapy.