Three-dimensional treatment planning computer-based vs nomogram-based implant technique for prostate carcinoma

The use of three-dimensional (3D) treatment planning computers for determining seed placement in prostate brachytherapy has become more widespread. This study compares the dosimetric differences between prostate implants performed by using 3D treatment planning computers vs the traditional nomogram approach. During a five-month period, 19 transperineal ultrasound-guided conformal prostatic implants were performed. Of these patients, 14 received a planning computed tomography (CT) scan with nomogram approach, while five patients underwent planning ultrasound with 3D computerized treatment planning. All patients underwent postoperative CT scans for dosimetric analysis. Implants were evaluated based on the percentage of prostate receiving the prescribed dose, minimal dose received by 100% and 90% of the prostate, and dose to the urethra and rectal mucosa. Results showed all patients had adequate glandular coverage, and there were no statistically significant dosimetric differences between the two groups. However, the 3D treatment planning group did require fewer mCi/cc compared with the nomogram group. Use of 3D treatment planning computers or nomogram- based treatment planning can provide equivalent dosing for prostate implants when performed by an experienced brachytherapist; however, the use of a 3D treatment planning and linear array ultrasound probe should greatly decrease the involved learning curve.