A Study on Image Reconstruction for Seed Localization for Permanent Prostate Brachytherapy

Hong, Ju Young; Rah, Jeong Eun; Suh, Tae Suk

Abstract

PURPOSE: This study was to design and fabricate a phantom for prostate cancer brachytherapy to validate a developed program applying a 3-film technique, and to compare it with the conventional 2-film technique for determining the location of an implanted seed.
MATERIALS AND METHODS
The images were obtained from overlapped seeds by randomly placing a maximum of 63 seeds in the anterior-posterior (AP) position and at -30degrees to 30degrees at 15degrees intervals. Images obtained by use of the phantom were applied to the image processing procedure, and were then processed into the development program for seed localization. In this study, cases were set where one seed overlapped, where two seeds overlapped and where none of the three views resolved all seeds. The distance between the centers of each seed to the reference seed was calculated in a prescribed region. This distance determined the location of each seed in a given band. The location of the overlapped seeds was compared with that of the 2-film technique.
RESULTS
With this program, the detection rate was 92.2% (at +/-15degrees), 94.1% (at +/-30degrees) and 70.6% (compared to the use of the 2-film technique). The overlaps were caused by one or more than two seeds that overlapped; the developed program can identify the location of each seed perfectly. However, for the third case the program was not able to resolve the overlap of the seeds.
CONCLUSION
This program can be used to improve treatment outcome for the brachytherapy of prostate cancer by reducing the number of errors in the process of reconstructing the locations of perfectly overlapped seeds.