HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH RSS TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Supplemental Appendix B Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Watchman, C. J. Articles by Bolch, W. E. Search for Related Content PubMed PubMed Citation Articles by Watchman, C. J. Articles by Bolch, W. E.

Absorbed Fractions for -Particles in Tissues of Trabecular Bone: Considerations of Marrow Cellularity Within the ICRP Reference Male

¹ Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida
² Department of Physics and Astronomy, Francis Marion University, Florence, South Carolina
³ Department of Health Physics, University of Nevada–Las Vegas, Las Vegas, Nevada
⁴ Department of Neurosurgery, University of Florida, Gainesville, Florida
⁵ Department of Radiology, Johns Hopkins University, Baltimore, Maryland
⁶ Department of Biomedical Engineering, University of Florida, Gainesville, Florida

-Particles are of current interest in radionuclide therapy due to their short range and high rates of energy transfer to target tissues. Published values of -particle absorbed fraction in the skeletal tissues, as needed for patient-specific dosimetry under the MIRD schema, do not generally account for its variation with particle energy or skeletal site. Furthermore, variations in -particle absorbed fraction with marrow cellularity have yet to be fully considered. Methods: In this study, a 3-dimensional (3D) chord-based radiation transport model (or 3D-CBIST) is presented, which combines (a) chord-based techniques for tracking -particles across bone trabeculae, endosteum, and marrow cavities and (b) a spatial model of the marrow tissues that explicitly considers the presence of marrow adipocytes. Chord-length distributions are taken from a 44-y male subject (ICRP [International Commission on Radiological Protection] Reference Male) and are identical to those used currently for clinical dose estimates for ß-particle emitters. Results: Values of (active marrowactive marrow) given by the 3D-CBIST model are shown to be considerably lower than = 1.0 assumed under the ICRP Publication 30 and 2003 Eckerman bone models. For example, values of absorbed fraction for the self-dose to active bone marrow in the ribs, cervical vertebra, and parietal bone are 0.81, 0.80, and 0.55 for 6-MeV -particles and are 0.74, 0.72, and 0.43 for 9-MeV -particles, where each is evaluated at ICRP reference cellularities in the 3D-CBIST model (72%, 72%, and 42%, respectively, at age 25 y). Conclusion: Improvements in patient-specific dosimetry of skeletal tissues require explicit consideration of not only changes in target mass with variable patient marrow cellularity (i.e., active marrow) but also corresponding changes in values of the absorbed fraction. The data given in this study provide a more-firm basis for application of the MIRD schema to patient-specific dosimetry for newly developing therapies using -particle emitters.

Key Words: radionuclide therapy • -particles • absorbed fraction • marrow cellularity • bone dosimetry.

This article has been cited by other articles:

				G. Sgouros, J. C. Roeske, M. R. McDevitt, S. Palm, B. J. Allen, D. R. Fisher, A. B. Brill, H. Song, R. W. Howell, G. Akabani, et al. MIRD Pamphlet No. 22 (Abridged): Radiobiology and Dosimetry of {alpha}-Particle Emitters for Targeted Radionuclide Therapy J. Nucl. Med., February 1, 2010; 51(2): 311 - 328. [Abstract] [Full Text] [PDF]

				J. G. Hunt, C. J. Watchman, and W. E. Bolch Calculation of absorbed fractions to human skeletal tissues due to alpha particles using the Monte Carlo and 3-d chord-based transport techniques Radiat Prot Dosimetry, November 1, 2007; 127(1-4): 223 - 226. [Abstract] [Full Text] [PDF]

				G. Sgouros Toward Patient-Friendly Cell-Level Dosimetry J. Nucl. Med., April 1, 2007; 48(4): 496 - 497. [Full Text] [PDF]

				J. M. Brindle, A. A. Trindade, A. P. Shah, D. W. Jokisch, P. W. Patton, J. C. Pichardo, and W. E. Bolch Linear Regression Model for Predicting Patient-Specific Total Skeletal Spongiosa Volume for Use in Molecular Radiotherapy Dosimetry J. Nucl. Med., November 1, 2006; 47(11): 1875 - 1883. [Abstract] [Full Text] [PDF]