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SU‐G‐TeP3‐08: Pre‐Clinical Radionuclide Therapy Dosimetry in Several Pediatric Cancer Xenografts
Author(s) -
Marsh I,
Otto M,
Weichert J,
Baiu D,
Bednarz B
Publication year - 2016
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 - 10.1118/1.4957088
Subject(s) - nuclear medicine , dosimetry , voxel , radionuclide therapy , medicine , absorbed dose , monte carlo method , radiation treatment planning , partial volume , imaging phantom , radiation therapy , radiology , mathematics , statistics
Purpose: The focus of this work is to perform Monte Carlo‐based dosimetry for several pediatric cancer xenografts in mice treated with a novel radiopharmaceutical 131 I‐CLR1404. Methods: Four mice for each tumor cell line were injected with 8–13 µCi/g of the 124 124I‐CLR1404. PET/CT images of each individual mouse were acquired at 5–6 time points over the span of 96–170 hours post‐injection. Following acquisition, the images were co‐registered, resampled, rescaled, corrected for partial volume effects (PVE), and masked. For this work the pre‐treatment PET images of 124 I‐CLR1404 were used to predict therapeutic doses from 131 I‐CLR1404 at each time point by assuming the same injection activity and accounting for the difference in physical decay rates. Tumors and normal tissues were manually contoured using anatomical and functional images. The CT and the PET images were used in the Geant4 (v9.6) Monte Carlo simulation to define the geometry and source distribution, respectively. The total cumulated absorbed dose was calculated by numerically integrating the dose‐rate at each time point over all time on a voxel‐by‐voxel basis. Results: Spatial distributions of the absorbed dose rates and dose volume histograms as well as mean, minimum, maximum, and total dose values for each ROI were generated for each time point. Conclusion: This work demonstrates how mouse‐specific MC‐based dosimetry could potentially provide more accurate characterization of efficacy of novel radiopharmaceuticals in radionuclide therapy. This work is partially funded by NIH grant CA198392.