Iron-59 Absorption Measurements by Whole-body Counting and Faecal Recovery Techniques A Study of Experimental Errors

Abstract

An assess-ment has been made of the types and magnitudes of errors involved in Fe59 intestinal absorption measurements by whole-body counting, employing a stationary single-crystal arrangement with the patient sitting on a chair in a simple "open booth" of shielding iron. The counting-statistical variation and the errors due to different positioning were found to be relatively minor, the major source of error being changes in counting efficiency caused by redistribution of the activity within the body. The total standard deviation due to random variation was found to be about 10%. A comparison with data based on fecal collection did not reveal any large systematic errors, but indicated a possible trend of too high retention values from whole-body counting as compared with the results derived from measurements of feces; this error, however, did not exceed 20%, and might partly be explained by an overestimation of the retention as obtained from the fecal collection data.