Real-Time Magnetic Resonance Imaging-Guided Brachytherapy in the Treatment of Selected Patients with Clinically Localized Prostate Cancer

Abstract

Background and Purpose: A real-time three-dimensional magnetic resonance imaging (MRI)-guided implant technique has been designed and implemented. This report summarizes the dosimetry achieved and the acute morbidity in the first patients. Patients and Methods: To date, 43 patients with clinical stage T1cNxM0 prostate cancer, serum prostate specific antigen <10 ng/mL, and biopsy Gleason score no higher than 3 + 4 have been treated. The procedure was performed using an open magnet, with axial T1-weighted and fast spin echo images. The prescribed minimum radiation dose to the peripheral zone was 160 Gy. The total activity implanted ranged from 18.8 to 47.5 mCi using 43 to 120 (median 80) 125I seeds. Dosimetric analyses were performed intraoperatively in real time for the tumor, anterior rectal wall, and prostatic urethra. Results: The percent of the clinical target volume receiving the prescription dose was 89% to 99% (median 96%). Using a conservative estimate of 164 Gy, no more than 9% of the ure...