PubMed · 5154240
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R Henry. Isotope generators. Present status and future development.. https://pubmed.ncbi.nlm.nih.gov/5154240/
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UNLABELLED: We describe the development of a biokinetic model which permits an estimation of organ activities and the dosimetry of a bolus of 15O-water. The aim of this study was to estimate time-activity functions and deduce the cumulated activities in different organs so that the radiation absorbed dose values can be estimated. METHODS: The model we used includes the right heart chambers, lungs, left heart chamber, brain, liver, kidneys, muscles, gastrointestinal tract and the remainder of the body. Activity in an organ will decay by physical decay with the decay constant, lambda, and can diffuse in the organ. An exception is the heart, where blood is ejected from the heart chambers. Depending on the location of the organ in relation to the blood sampling point, organ activities can be calculated by convolution or deconvolution. RESULTS: The radiation absorbed dose values were estimated and an effective dose equivalent HE of 1.16 microSv/MBq (4.32 mrem/mCi) as well as an effective dose E of 1.15 microSv/MBq (4.25 mrem/mCi) were calculated. The cumulated activities in select organs measured by PET gave good agreement with the values calculated by this model. CONCLUSION: The values of effective dose equivalent and effective dose for bolus administration of 15O-water calculated from the absorbed doses estimated by the proposed kinetic model are almost three times higher than those previously published. A total of 8700 MBq (235 mCi) of 15O-water can be administered if an effective dose of 10 mSv (1 rem) is accepted.
AIM: To establish a simple method for estimating half-life of drugs obeying Michaelis-Menten elimination kinetics. METHODS: A linear relationship is sketched between elimination half-life and drug concentration in blood that obey Michaelis-Menten elimination kinetics. A simple method is proposed to draw a regression line of blood drug concentration vs time after a single bolus intravenous injection. RESULTS & CONCLUSION: The elimination half-life can be read from the regression line. The method can also be used to estimate the time required for the plasma concentration of a drug to decrease any fraction.