Tomographic imaging with a miniature gamma camera

The feasibility of single-photon emission computed tomography (SPECT) using a prototype miniature gamma camera has been investigated. The camera consists of a sodium iodide (NaI(Tl)) crystal coupled to a single position-sensitive photomultiplier tube (PSPMT) and uses a maximum-likelihood algorithm to determine position estimates. The prototype system has been used to obtain projection data from a phantom, filled with technetium-99m (Tc-99m), that simulates a human forearm. Tomographic images were reconstructed via filtered backprojection. Images were also reconstructed from subsets of the projection data to examine the effects of limited-projection and limited-angle tomography. Using all projection data, objects as small as 2 mm are resolved. Larger objects are easily seen, even when the images are reconstructed from as few as 45 projections. In limited-angle reconstructions, large objects are also easily visualized, although artifacts exist. The authors´ results indicate that the prototype camera can be adapted for tomographic imaging