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Interpretation of pre‐ versus postimplant TRUS images
Author(s) -
Smith Stephen,
Wallner Kent,
Merrick Gregory,
Butler Wayne,
Sutlief Steven,
Grimm Peter
Publication year - 2003
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 - 10.1118/1.1568980
Subject(s) - nuclear medicine , brachytherapy , medicine , dosimetry , prostate , radiology , radiation therapy , cancer
In order to summarize the inter‐observer variability of pre‐ and postimplant TRUS image interpretation. Ten patients treated with Pd‐103 brachytherapy were studied. Preimplant prostate volumes ranged from 21 to 51 cm 3 . The number of sources implanted ranged from 74 to 155, and the number of sources per cm 3 prostate volume ranged from 3.0 to 4.3. A set of transverse images (6 MHz) were taken immediately prior to and following source placement. Original printer images were sent to four investigators and the prostate outlined independently on a cellophane overlay. The overlays were digitized into a Varian MMS 7.0 treatment planning system (Charlottesville, VA) for volume determinations. There was moderate interobserver variability in TRUS volume determination, accentuated for the postimplant images. The standard deviations varied from 2% to 13% of the mean (median: 7%) for preimplant volumes, versus 7% to 32% (median: 13%) for postimplant volumes. Interobserver prostatic edge (border) localization variability was greatest at the base and apex, with closer agreement along the posterior border. For preimplant images, the majority of edge points were within 1.0 mm of the mean. At each coordinate, with the exception of the anterior base, the majority of points were within 2.0 mm of the mean. In general, border identification variability was greater in the post implant images. While all prostate imaging modalities suffer from interobserver variability, preimplant and postimplant TRUS appears capable of consistently determining prostatic volume and borders. It appears that intraoperative TRUS‐based dosimetry is a practical goal, provided that seed location coordinates can be added to the prostatic edge information derived from TRUS images.