An assessment of position sensitive photomultiplier tubes for high resolution 3D imaging

The results of studies conducted with a small field of view camera based on a position sensitive photomultiplier tube (PSPMT) and a pixelized scintillator crystal made of CsI(Tl), are reported. Using a computer-controlled step motor allowing object rotation, projection data from several angles are acquired. With the use of a filtered backprojection algorithm, slices of the object are obtained while three dimensional (3D) reconstruction of the object is carried out using a modified marching cubes algorithm. Phantom studies have shown a spatial resolution of 2 to 3 mm in both two and three dimensions. Furthermore, mice experiments have shown successful SPECT imaging of small organs as well as satisfactory detection and exact localization of experimentally induced tumors. Larger field of view PSPMTs, which are already commercially available, can be used to allow imaging of small human organs (thyroid, breast), while a larger number of PSPMTs will lead to a substantial reduction of the required examination time. Thus, a high-resolution SPECT system, based on the same principle of operation, can be developed and used clinically as a low cost breast tomograph