Premium
Three‐dimensional dosimetric analysis and quantitative bremsstrahlung SPECT imaging for treatment of nonresectable pancreatic cancer using colloidal phosphorus‐32
Author(s) -
Parsai E. Ishmael
Publication year - 1997
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 - 10.1118/1.598074
Subject(s) - voxel , nuclear medicine , imaging phantom , dosimetry , monte carlo method , single photon emission computed tomography , physics , medicine , mathematics , radiology , statistics
A clinically applicable methodology was developed to: (1) co‐register the reconstructed three‐dimensional images from CT and SPECT, and (2) determine the 3‐D absorbed dose distribution from bremsstrahlung SPECT images for patients undergoing infusional brachytherapy using colloidal P‐32. The image co‐registration helps verify that the region of P‐32 activity distribution corresponds to the anatomic site selected for injection. For outer surfaces, the body contours obtained from bremsstrahlung SPECT data were co‐registered with corresponding contours from CT. For the administered activity, a 3‐D surface was generated by mapping the iso‐counts in the SPECT image in real coordinates. The corresponding surface objects from the CT then were matched with the SPECT using an outer surface‐fitting algorithm. The accuracy of the fit measured as the mean distance between the SPECT and CT surfaces was then calculated. Calibration curves were generated from phantom studies and activity per voxel from the attenuation corrected measured counts per voxel were determined. The cumulative activity at each voxel position was then converted to dose (Gy) using a Monte Carlo based P‐32 point dose kernel in water. Two‐ and three‐dimensional quantitative dose distributions were then generated and projected on the reconstructed SPECT or CT slices and dose‐volume histograms were analyzed.