Investigation of the optimisation of imaging parameters with a gamma camera

The diagnosis of a large percentage of nuclear medicine studies depends on the principle that the clinician should detect a hot or cold lesion against a relative uniform background activity. The lesion detectability is influenced by various physical factors, such as resolution, contrast count density and lesion diameter, as well as psychophysical factors. Most of these factors are interdependent. One of the objectives of this study was to investigate the influence of the above-mentioned factors on lesion detectability as well as their interdependence. As the final image is displayed on film, all development conditions were standardised. A single emulsion x-ray film with a high gamma was selected. A specially designed phantom which simulated cold lesions in a uniform background was used to investigate the interdependence of the lesion diameter, contrast, count density and resolution. Lastly, the lesion detectability of a multi-purpose and high resolution collimator was compared for a cold lesion. There was no significant difference between the two collimators. 64 refs., 42 figs., 31 tabs