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Experimental evaluation of an online gamma‐camera imaging of permanent seed implantation (OGIPSI) prototype for partial breast irradiation
Author(s) -
Ravi Ananth,
Caldwell Curtis B.,
Pignol JeanPhilippe
Publication year - 2008
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2919559
Subject(s) - imaging phantom , gamma camera , collimator , brachytherapy , image resolution , detector , monte carlo method , nuclear medicine , biomedical engineering , pixel , computer science , dosimetry , computer vision , artificial intelligence , materials science , optics , medicine , physics , mathematics , radiology , radiation therapy , statistics
Previously, our team used Monte Carlo simulation to demonstrate that a gamma camera could potentially be used as an online image guidance device to visualize seeds during permanent breast seed implant procedures. This could allow for intraoperative correction if seeds have been misplaced. The objective of this study is to describe an experimental evaluation of an online gamma‐camera imaging of permanent seed implantation (OGIPSI) prototype. The OGIPSI device is intended to be able to detect a seed misplacement of 5 mm or more within an imaging time of 2 min or less. The device was constructed by fitting a custom built brass collimator ( 16 mm height, 0.65 mm hole pitch, 0.15 mm septal thickness) on a 64 pixel linear array CZT detector (eValuator‐2000, eV Products, Saxonburg, PA). Two‐dimensional projection images of seed distributions were acquired by the use of a digitally controlled translation stage. Spatial resolution and noise characteristics of the detector were measured. The ability and time needed for the OGIPSI device to image the seeds and to detect cold spots was tested using an anthropomorphic breast phantom. Mimicking a real treatment plan, a total of 52Pd103seeds of 65.8 MBq each were placed on three different layers at appropriate depths within the phantom. The seeds were reliably detected within 30 s with a median error in localization of 1 mm . In conclusion, an OGIPSI device can potentially be used for image guidance of permanent brachytherapy applications in the breast and, possibly, other sites.