When the PMT and preamplifier are out of order, it is impossible to make a correct diagnosis because of defects on the scintigram. However, repair of the equipment may take a long time. In order to perform emergent whole-body scintigrams in the event of such breakdowns, we have developed a new approach named the lead-shield method. The major principles of this method involve placing a lead shield on the gamma camera such that it corresponds to the area of the abnormal PMT and making use of the normal area of the detector. The lead shield, 2mm thick and 1.5 times as wide as the defect on a planar image, was situated perpendicular to the scan plane of the whole-body scintigram. The results showed that whole-body scintigrams obtained by the lead-shield method had the same quality as those obtained by the conventional method, and the spatial resolution and uniformity showed nearly no change despite some disadvantages such as lower sensitivity and shorter scan length. The lead-shield method can be a useful tool for the performance of whole-body scintigrams in cases of emergency, when the PMT and preamplifier are out of order.
