Simultaneous irradiation, or ProstRcision, is a prostate cancer treatment provided exclusively at the Radiotherapy Clinics of Georgia. It involves high-dose brachytherapy followed by external beam radiation therapy while the brachytherapy seeds are still active. An integral part of the procedure is the targeting of a post-treatment serum prostate-specific antigen (PSA) nadir of 0.2 ng/mL and an assessment of treatment failure if the PSA level fails to reach this nadir or subsequently rises above it. The goal of simultaneous irradiation is to destroy the prostate tissue; it is intended as an alternative to radical prostatectomy or conventional radiation monotherapy.