Errors in External Counting Method of Hepatic Blood Flow Index Using Colloidal Radiogold

The external counting method of hepatic blood flow index using colloidal radiogold is useful in the clinical examination. Variations of hepatic blood flow index according to the position of the scintillation detector over the liver of each patient were studied. And variations of hepatic blood flow index calculated from the same accumulation curve by different examiners were also studied. Method: 2-4 scintillation detectors were placed on the different parts over the liver in each patient at the same time. Then 55 accumulation curves in 21 patients were recorded. Hepatic blood flow indexes were calculated from these 55 curves and compared. And also hepatic blood flow indexes were calculated by different 18 examiners from 6 accumulation curves in 2 patients and compared. Results: In 6 of 21 patients, S.D, of K (1-n) according to the position of detectors were more than 0.010. In 3 of these 21 cases, S.D. of K (1-n) were between 0.006 and 0.009. S.D. of K values calculated from the same accumulation curve by different 18 examiners were between 0.015 and 0.023 in six accumulation curves. It was found that the K value varied according to the position of detectors and depending upon personal judgement, i.e, the saturation level decided by the individual, plotting activity value on the section papar, drawing the slope and so on. From the results of these two origins of errors, we must deal with the hepatic blood flow index, knowing that the second decimal number of hepatic blood flow index (K) varies in the same patient at the same time according to the position of the detector and even more according to the personal judgement. And it seems meaningless to compare third decimal number in hepatic blood flow index.