Deadtime of a single-crystal gamma camera in abdominal imaging.

The deadtime of a single-crystal gamma camera depends on the scattering condition, and differs among patients. The aim of this study was to estimate deadtime in posterior abdominal imaging. Radionuclide angiography of the posterior abdominal view was performed in 23 patients with a point source in the field-of-view, and temporal changes in count loss were assessed. The deadtime for each patient was calculated based on the count loss for the point source. The estimated deadtime ranged from 7.83-12.52 microsec, and was significantly correlated with the ratio of body weight in kg to body height in cm (y=13.143x+5.595, r=0.852, p<0.001). Count loss was successfully corrected using the deadtime predicted with the regression equation. In conclusion, the deadtime in posterior abdominal imaging can be predicted for each patient from the body weight and body height. The predicted deadtime may aid in improving the reliability of quantitative measurements by scintigraphic techniques.