Performance characteristics of seven-pinhole tomography.

Abstract

Vogel et al (1978) recently published a new method of planar emission tomography employing a standard wide-field Anger scintillation camera and a sevenpinhole collimator for the tomographic visualization of 2O1T1 myocardial perfusion under exercise and at rest. Initial reports indicated that improved accuracy in clinical diagnostic cardiac perfusion was obtained compared with non-tomographic scintigraphy (Vogel et al, 1978; 1979), although a recent publication from our laboratory employing receiver-operating-characteristic (ROC) curve analysis showed no difference in diagnostic ability between conventional planar and sevenpinhole tomographic imaging (Wainwright et al, 1980). Clinical applications other than myocardial perfusion are being investigated, such as blood pool (Chang & Henkin, 1980) and liver (Brookeman et al, 1982). This report describes an evaluation of some performance characteristics of the system for three-pinhole sizes. A commercially available system,† consisting of a seven-pinhole collimator and reconstruction software, was employed with a wide-field gamma camera‡ and digital computer system.§ The collimator includes three sets of lead pinholes, of diameter 4.5 mm, 5.5 mm or 7.5 mm. The collimator pinholes are in a plane 12.7 cm from the camera crystal and 6.6 cm apart from each other in a hexagonal array. Seven independent projections are simultaneously imaged. The iterative reconstruction algorithm refocuses the seven sector images to generate multiple slices parallel to the pinhole plane. Following clinical practice, a 30% energy window was used with 201Tl or 195 Au sources and a 20% window with 99Tcm or 57Co sources.