Clinical implementation of new region-specific S-values for marrow dosimetry: Dose distribution vs mean marrow dose in radioimmunotherapy of leukemia
- Oak Ridge National Lab., TN (United States); and others
Radiolabeled antibodies that target hematologic disease often exhibit a highly variable as well as non-uniform spatial distribution within the marrow. Mean marrow absorbed dose estimates obtained using a single S-value to represent the absorbed dose per unit cumulated activity for the whole marrow may not adequately reflect potential normal marrow morbidity or tumor cytotoxicity in different marrow regions. New, region-specific, S-factors for marrow, developed at the Oak Ridge National Laboratory, were used to calculate the absorbed dose to three different marrow regions in 9 leukemia patients that were administered trace-labeled I-131-HuM195, the humanized version of (anti-CD33) M195 antibody. Time-activity curves for each marrow region were obtained by drawing contours around: the head and neck of both femurs, both humeral heads, and the third and fourth lumbar vertebra, in each of four daily conjugate-view images that were collected starting the day of the infusion. Based on data gathered in the regions over the spine and femur, we predict absorbed doses to the active marrow for various regions of the skeleton ranging from 0.16-0.63 mGy/MBq, with a region-weighted average of 0.46 mGy/MBq. This compares with estimates mGy/MBq, respectively. Analysis of marrow dosimetry by region and in a dose-volume histogram format will provide a more reliable dosimetry picture for the clinician than provided by the single dose estimates available previously.
- OSTI ID:
- 197984
- Report Number(s):
- CONF-940605--
- Journal Information:
- Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: Suppl.5 Vol. 35; ISSN 0161-5505; ISSN JNMEAQ
- Country of Publication:
- United States
- Language:
- English
Similar Records
Estimation of radiation absorbed doses to the red marrow in radioimmunotherapy
Dose conversion factors for marrow and bone by skeletal regions