Innovative Planning and Guidance System for Prostate Focal Brachytherapy

A key feature of low-dose brachytherapy is that irradiation affects only a local area around the inserted radiation sources. The exposure of healthy tissues around these sources is then reduced. However, the number of adverse events remains high (about 79% of patients with sexual problems and 30% of patients with urinary incontinence) and brachytherapy is no better than other treatment options for Preservation of the urethral apparatus (about 40% of patients). The current technique for the implantation of radioactive sources, which has not been revised since the early 1980s, consists in imaging the prostate at the beginning of the intraoperative procedure with transrectal ultrasound in order to evaluate the size and shape of the prostate . This information is then used to identify the best distribution of the dose of radiation to be administered to each patient. This treatment planning step is based on a procedure where the operator manually places 50 to 100 grains of iodine in the prostate. These grains are inserted transperinally under transrectal 2D ultrasound control, using needles through a transperineal grid with several needle guides evenly spaced 5 mm apart. This is an arduous task because this manual grain placement procedure must take into account the dose to be administered to the prostate without exceeding the dose limit for the surrounding organs at risk (rectum, urethra). In addition, the overestimation of the dose formality called TG-43 and the inaccurate grain placement can contribute to the creation of cold spots where no dose is administered. It may be responsible for recurrences of prostate cancer after brachytherapy treatment. Although brachytherapy dosimetry has been extensively researched, the TG-43 dose formalism has been the benchmark for the last 20 years. Moreover, from an economic point of view, the high side-effects rates of the treatment of prostate cancer result in particularly expensive post-treatment costs. The search for improved so