Evaluation of an intraoperative iodine-125 brachytherapy implant technique

The purpose of this study was to evaluate the usefulness of an intra-operative planning method in brachytherapy prostate seed placement by comparing pre-planning and intra-operative planning techniques. This comparison was achieved by a virtual-planning technique in which the pre-planned seed and needle positions are superimposed on the intra-operatively obtained volume study. Dosimetric evaluation of each implant was based on the dose volume histogram (DVH) generated from CT studies and analysis of image and seed numbers, target volume and inferior extent of posterior planes. These parameters showed that greater dosimetric values are noted in the intra-operative technique. The study demonstrated a benefit from an intra-operative approach to seed placement as opposed to a pre-planned approach. Defining the sagittal contours of the prostate, immediately prior to implant, reduced the inferior extent of seeds placed in the most posterior aspect of the prostate, thereby decreasing the probability for rectal complication and morbidity. Additionally, more correctly delineating the tranverse prostate contours at the time of seed placement resulted in fewer seeds placed in the periprostatic region, outside the PTV, thus reducing potential seed migration and increasing prostate dose coverage