Individualized estimation of cumulated activity distribution in patients undergoing 18F-FDG PET scans based on the biokinetic model
Objective To achieve personalized assessment of cumulated activity distribution in patients undergoing 18F-FDG PET scans using the biokinetic model based on the single-time-point PET images.Methods A biokinetic compartmental model for the organs of interest was established,and the variation of activities in each compartment was described as a set of differential equations.The PET image data at a specific time point of each patient was used to obtain the kinetic model parameters which were then optimized by a simulated annealing algorithm to calculate the cumulated activity of each organ.Additionally,the effects of different voiding patterns on the cumulated activity of the bladder were analyzed.Considering the heterogeneity of radioactive nuclide distribution in organs,a whole-body cumulated activity distribution map was computed,and the accuracy of the proposed method was evaluated by comparison with the existing methods.Results For the 11 cases analyzed in the study,the calculation results of the biokinetic model generally showed a good agreement with experimental data,with an average deviation of less than 15%.Meanwhile,under different urinary excretion conditions,the average cumulated activity in the bladder differed by up to 2.4 times,indicating the positive significance of enforced urination in reducing radiation exposure.The comparison with the biokinetic data obtained from ICRP Publication 128 revealed relatively large deviations for certain organs such as the brain and heart,with standard deviations of 61.0%and 46.3%,respectively.Conclusion The constructed biokinetic model can effectively estimate the individualized cumulated activity distribution in patients undergoing PET scans,providing valuable insights for the internal dosimetry assessment.
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