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New trends in clinical and retrospective dosimetry

Jung Aleksandra, Matusiak Katarzyna

Bio-Algorithms and Med-Systems

2023

Vol. 19, no. 1

69--73

Selecting the proper dosimeter and methodology is crucial for accurate dose measurement, especially since the requirements are different for clinical and retrospective dosimetry. Regardless of the field-radiotherapy, X-ray diagnostic radiology or nuclear medicineefforts are continuously being made to improve radiation measurement accuracy through the development of new dosimeters, accurate calibration of instrumentation, training of staff, proper quality control and enhancement of radiation safety procedures. For instance, for retrospective dose estimation during radiation accidents, the selection of the appropriate material and knowledge of the intrinsic background signal of the selected material are crucial. In both clinical and retrospective dosimetry it is important to have adequate protocols as well as expertise in possible uncertainties, discussed here based on the authors own research.

Bile acid kinetic modeling in end-stage liver support patients

Jung Aleksandra, Korohoda Przemyslaw, Krisper Peter, Stadlbauer Vanessa, Stauber Rudolf E., Schneditz Daniel

Biocybernetics and Biomedical Engineering

2020

Vol. 40, no. 2

764--773

Background & Aims: Solute generation rates, distribution volumes and compartment effects control the in vivo efficiency of any extracorporeal therapy such as extracorporeal liver support (ELS) used to remove bile acids accumulating in acute-on-chronic liver patients. The aim of this study was to identify and to examine kinetic parameters of two major bile acids using mathematical modeling. Methods: The kinetics of cholic (CA) and chenodeoxycholic acid (CDCA) were described by one- and two-compartment models with central elimination by decreasing or constant extracorporeal clearance, constant bile acid generation rate, and constant apparent distribution volume. Concentration profiles collected in 13 ELS sessions done in 8 patients were included for model calculations Results: For the one-compartment model, the average volumes and generation rates were 30 ± 6 [l], 0.19 ± 0.06 [μmol/min] for CA and 22 ± 5 [l], 0.29 ± 0.08 [μmol/min] for CDCA, respectively. For the one-compartment model and average normalized concentrations, the volumes and genera- tion rates were 25 [l], 0.28 [μmol/min] for CA and 18 [l], 0.37 [μmol/min] for CDCA, respectively. For the two-compartment model, average normalized concentrations, the same initial concentration in both compartments, and assuming a 10% post-treatment rebound, the volume and generation rates were 25 [l], 0.27 [μmol/min] for CA and 19 [l], 0.32 [μmol/min] for CDCA, respectively. Conclusions: The generation rate for CDCA is higher when compared to that of CA and independent of the number of compartments. Assuming a constant extracorporeal clearance overestimates generation rate and distribution volume. The kinetic parameters of one-and two-compartment models are comparable for the same bile acid.