2331: Dosimetric Evaluation of Permanent Prostate Brachytherapy Using Cs-131 Sources

Abstract

To evaluate the dosimetric properties of Cs-131 sources in permanent prostate brachytherapy. From March 2005 through January 2006, 58 patients underwent permanent interstitial brachytherapy prescribe to 100 Gy mPD for clinical stage T1c-T2c (2002 AJCC) prostate cancer. All patients were implanted using Cs-131 sources (Isoray Model Cs-1). Post-implant dosimetry from day-0 CT scans of these patients implants was performed generating dosimetric data as recommended by the American Brachytherapy Society. These include D90, V100, V150, Urethral D30, and Rectal V100. Mean D90 was 104.2% (range 95.5 - 112.2%). Mean V100 was 96.7% (range 93.4–98.8%) Mean V150 was 29.4% (range 22.3–38.8%). Mean urethral D30 was 123.4 % (range 119.4 - 132.4%). Mean rectal V100 was 0.32 cc (range 0–0.72 cc). Permanent interstitial prostate brachytherapy using Cs-131 sources allows for excellent dosimetic results. Cs-131 achieves excellent gland coverage with minimal inhomogeneity. Urethral and rectal doses are also well within the accepted range.