Tissue Attenuation Corrections in Gamma Scintigraphy

Abstract

ABSTRACT Gamma scintigraphy may be used to quantify deposition patterns from aerosol inhalers provided that appropriate corrections are made for the attenuation of gamma rays by different body tissues. Tissue attenuation correction factors (ACFs) were determined in a group of 10 healthy volunteers, using four different techniques: measurement of body thickness, transmission scans, a sealed radioactive source, and a perfusion scan. Different combinations of these ACFs were then used to calculate deposition values from data obtained in the same volunteers in a previous study in which the deposition pattern of a drug inhaled from two different asthma inhalers was investigated. In addition, deposition patterns were determined from data that had not been corrected for tissue attenuation. Lung and stomach ACFs were relatively independent of the correction method (means, 1.84–2.16 for the lungs and 3.42–3.81 for the stomach), although ACFs for the oropharynx were more variable (means, 1.41–2.29). There were sign...