Journal article
Dosimetry of [15O]water: A physiologic approach
Medical physics (Lancaster), Vol.23(1), pp.159-168
01/1996
DOI: 10.1118/1.597793
PMID: 8700028
Abstract
Earlier dosimetry estimates for [15O]water assumed its instantaneous equilibrium with total body water. This assumption leads to an underestimation of the absorbed doses to organs with high blood flows, since the biodistribution of this short‐lived radiopharmaceutical is dependent upon blood flow to organs. We have developed a physiologically based whole body blood flow model (WBBFM) using a commercially available icon‐driven mathematical simulation software package and applied it to the reevaluation of [15O]water dosimetry in humans. The WBBFM uses multiple parallel compartments to represent organs, heart chambers, the injection site for [15O]water, and blood sampling sites (arterial and venous). Input values to the WBBFM include organ blood flows, organ masses, organ water volumes, organ:blood partition coefficients, injected activity and S‐values of [15O]. The WBBFM is based on the same assumptions that are used in calculating regional blood flow using [15O]water and simulates the human body closely in its physiologic response. The activity in each organ is derived from the simulation and is used to calculate absorbed doses. The WBBFM calculated absorbed doses in μGy/MBq (mrad/mCi) to various organs are as follows: heart—2.66 (9.84), kidneys—2.20 (8.15), thyroid—1.83 (6.78), brain—1.66 (6.13), ovaries—1.25 (4.61), breast—1.24 (4.59), and small intestine—1.03 (3.83). These values are approximately two‐ to threefold higher than the earlier estimates of Kearfott [J. Nucl. Med. 23, 1031–1037 (1982)] and similar to the recent findings of Herscovitch et
al. [J. Nucl. Med. 34, 155P (1983)]. We believe this approach yields more realistic dosimetry estimates for [15O]water. Accordingly, we have revised the amount of [15O]water administered during regional blood flow studies at our institution. The relative ease and accuracy of this approach suggests its usefulness in dosimetry estimation for other freely diffusible radiopharmaceuticals.
Details
- Title: Subtitle
- Dosimetry of [15O]water: A physiologic approach
- Creators
- Shalini Narayana - Division of Nuclear Medicine, Department of Radiology, University of Iowa, Iowa City, Iowa 52242Richard D Hichwa - Division of Nuclear Medicine, Department of Radiology, University of Iowa, Iowa City, Iowa 52242Laura L Boles Ponto - Division of Nuclear Medicine, Department of Radiology, University of Iowa, Iowa City, Iowa 52242James A Ponto - Division of Nuclear Medicine, Department of Radiology, University of Iowa, Iowa City, Iowa 52242G. Leonard Watkins - Division of Nuclear Medicine, Department of Radiology, University of Iowa, Iowa City, Iowa 52242
- Resource Type
- Journal article
- Publication Details
- Medical physics (Lancaster), Vol.23(1), pp.159-168
- DOI
- 10.1118/1.597793
- PMID
- 8700028
- ISSN
- 0094-2405
- eISSN
- 2473-4209
- Number of pages
- 10
- Date published
- 01/1996
- Academic Unit
- Radiology; Research Administration; Pharmaceutical Sciences and Experimental Therapeutics; Physics and Astronomy; Radiation Oncology; Pharmacy Practice and Science
- Record Identifier
- 9984051539802771
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