Chromium-51 ethylene diamine tetra-acetic acid (51Cr-EDTA) total plasma clearance was evaluated using a multi-sample method (i.e. 12 blood samples) as the reference compared with several simplified methods which necessitated only one or few blood samples. The following 5 methods were evaluated: terminal slope-intercept method with 3 blood samples, simplified method of Bröchner-Mortensen and 3 single-sample methods (Constable, Christensen and Groth, Tauxe). Linear regression analysis was performed. Standard error of estimate, bias and imprecision of different methods were evaluated. For 51Cr-EDTA total plasma clearance greater than 30 ml.min-1, the results which most approximated the reference source were obtained by the Christensen and Groth method at a sampling time of 300 min (inaccuracy of 4.9%). For clearances between 10 and 30 ml.min-1, single-sample methods failed to give reliable results. Terminal slope-intercept and Bröchner-Mortensen methods were better, with inaccuracies of 17.7% and 16.9%, respectively. Although sampling times at 180, 240 and 300 min are time-consuming for patients, 51Cr-EDTA total plasma clearance can be accurately calculated for values greater than 10 ml.min-1 using the Bröchner-Mortensen method. In patients with clearance greater than 30 ml.min-1, single-sample techniques provide a good alternative to the multi-sample method; the choice of the method to be used depends on the degree of accuracy required.
Our results show that during ultrasound or stereotactic administration of radiolabeled compounds the radiation burden to the personnel involved in the procedure is virtually negligible. The surgeons too are exposed to a negligible radiation dose.
Measurements of 137Cs contamination in the urine of 37 individuals were performed in 1995 and 1996 in order to evaluate the 137Cs daily urinary excretion in the northwestern italian people ten years from the Chernobyl accident. The difference between the average 137Cs daily urinary excretion assessed for 1995 and for 1996 was not statistically significant. Using the values of urine contamination, an estimate of 0.2 Bq(-1) of mean ingested activity was obtained. A mean committed effective dose of about 1 microSv was determined as due to the 137Cs ingestion during 1 y at 10 y after the accident. Such a dose is lower by a factor of 10(3) than the corresponding value for the population of North Italy in the first year following the Chernobyl accident.
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