title: Online gamma-camera imaging of 103Pd seeds (OGIPS) for permanent breast seed implantation.
abstract: Permanent brachytherapy seed implantation is being investigated as a mode of accelerated partial breast irradiation for early stage breast cancer patients. Currently, the seeds are poorly visualized during the procedure making it difficult to perform a real-time correction of the implantation if required. The objective was to determine if a customized gamma-camera can accurately localize the seeds during implantation. Monte Carlo simulations of a CZT based gamma-camera were used to assess whether images of suitable quality could be derived by detecting the 21 keV photons emitted from 74 MBq (103)Pd brachytherapy seeds. A hexagonal parallel hole collimator with a hole length of 38 mm, hole diameter of 1.2 mm and 0.2 mm septa, was modeled. The design of the gamma-camera was evaluated on a realistic model of the breast and three layers of the seed distribution (55 seeds) based on a pre-implantation CT treatment plan. The Monte Carlo simulations showed that the gamma-camera was able to localize the seeds with a maximum error of 2.0 mm, using only two views and 20 s of imaging. A gamma-camera can potentially be used as an intra-procedural image guidance system for quality assurance for permanent breast seed implantation.
authors: Department of Medical Biophysics, University of Toronto, Canada.
authors: Ananth
authors: A
authors: Ravi
authors: Curtis B
authors: CB
authors: Caldwell
authors: Brian M
authors: BM
authors: Keller
authors: Alla
authors: A
authors: Reznik
authors: Jean-Philippe
authors: JP
authors: Pignol
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008954:Models, Biological; D009010:Monte Carlo Method; D009862:Online Systems; D010165:Palladium / Q000627:therapeutic use*; D019919:Prosthesis Implantation / Q000379:methods*; D011868:Radioisotopes / Q000627:therapeutic use*; D011877:Radionuclide Imaging / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted / Q000379:methods; D025321:Surgery, Computer-Assisted / Q000379:methods
chemical_list: D011868:Radioisotopes; D010165:Palladium