Estimation of absorbed dose for 2-[F-18]fluoro-2-deoxy-d- glucose using whole-body positron emission tomography and magnetic resonance imaging |
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Authors: | Hossain M Deloar Takehiko Fujiwara Miho Shidahara Takashi Nakamura Hiroshi Watabe Yuichiro Narita Masatoshi Itoh Masayasu Miyake Shoichi Watanuki |
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Institution: | (1) Cyclotron and Radioisotope Center, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai-980-77, Japan, JP |
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Abstract: | The purpose of this study was to measure the cumulated activity and absorbed dose in organs after intravenous administration
of 2-F-18]fluoro-2-deoxy-d-glucose (18F-FDG) using whole-body positron emission tomography (PET) and magnetic resonance imaging (MRI). Whole-body dynamic emission
scans for 18F-FDG were performed in six normal volunteers after transmission scans. The total activity of a source organ was obtained
from the activity concentration of the organ measured by whole-body PET and the volume of that organ measured by whole-body
T1-weighted MRI. The cumulated activity of each source organ was calculated from the time-activity curve. Absorbed doses to
the individuals were estimated by the MIRD (medical internal radiation dosimetry) method using S-values adjusted to the individuals.
Another calculation of cumulated activities and absorbed doses was performed using the organ volumes from the MIRD phantom
and the ”Japanese reference man” to investigate the discrepancy of actual individual results against the phantom results.
The cumulated activities of 18 source organs were calculated, and absorbed doses of 27 target organs estimated. Among the
target organs, bladder wall, brain and kidney received the highest doses for the above three sets of organ volumes. Using
measured individual organ volumes, the average absorbed doses for those organs were found to be 3.1×10–1, 3.7×10–2 and 2.8×10–2 mGy/MBq, respectively. The mean effective doses in this study for individuals of average body weight (64.5 kg) and the MIRD
phantom of 70 kg were the same, i.e. 2.9×10–2 mSv/MBq, while for the Japanese reference man of 60 kg the effective dose was 2.1×10–2 mSv/MBq. The results for measured organ volumes derived from MRI were comparable to those obtained for organ volumes from
the MIRD phantom. Although this study considered 18F-FDG, combined use of whole-body PET and MRI might be quite effective for improving the accuracy of estimations of the cumulated
activity and absorbed dose of positron-labelled radiopharmaceuticals.
Received 23 October 1997 and in revised form 31 January 1998 |
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Keywords: | : Absorbed Dose S-value MIRD phantom Whole-body positron emission tomography Magnetic resonance imaging |
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