| Abstract | This paper will briefly describe the gamma-ray scintillation camera, the positron camera, and a new instrument called the multiplane tomographic scanner. The scintillation camera, manufactured commercially by Nuclear-Chicago Corp., utilizes an 11-or 12-inch diameter sodium iodide crystal viewed by 19 phototubes and circuitry that reproduces the scintillations that occur in the crystal on a cathode-ray tube. Pulse-height selection is used to eliminate scattered γ rays. One of several image-forming collimators is used to project an image of the subject on the sodium iodide crystal. Then, the cathode-ray tube display is photographed for a period of time lasting from a second to several minutes, and a picture of the distribution of activity in the subject results. The image-forming collimators used at the present time are shown in Fig.1. At the upper left is the pinhole collimator, which gives best results for small organs such as the thyroid gland or a single kidney. It can also be used to take pictures of very large subjects such as the lung but is not as satisfactory for this purpose as the new diverging multichannel collimator. For highest resolution in small organs, the pinhole collimator is superior to all others. |
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