TRUS-probe integrated MOSkin detectors for rectal wall in vivo dosimetry in HDR brachytherapy: In phantom feasibility study

• MOSkins were placed on a TRUS probe to perform rectal wall in vivo dosimetry.
• Their response was studied in a gel phantom including a typical prostate implant.
• The average discrepancy between calculated and measured dose was −0.6 ± 2.6%.

The increasing complexity and high amount of dose per fraction delivered in prostate high dose rate (HDR) brachytherapy treatments call for the implementation of accurate and effective methods for the systematic and independent quality control of the overall treatment procedure. In this study, MOSkin detectors were placed on a trans-rectal ultrasound (TRUS) probe with the aim of performing both imaging and real time rectal wall in vivo dosimetry with the use of just one single instrument. After an adequate calibration of the detectors, which was carried out in a solid water phantom, the use of MOSkins integrated to the TRUS probe was studied in a gel phantom with a typical (simplified) prostate implant. Measured and calculated doses from the treatment planning system were compared, with a resulting very low average discrepancy of −0.6 ± 2.6%. The results are very promising and of particular clinical importance, however, further in vivo investigation is planned to validate the proposed method.