As usual, however, the scintillating crystals are not included in these contracts. Due to these contracts, each malfunction is reported to the company and all necessary actions are undertaken by the company to get the camera working again as soon as possible. Furthermore, each camera receives twice a year a preventitive maintenance, including a full recalibration of the camera. Once every week, the engineers of our division check the uniformity of each scintillation camera for the most often used collimater set, which are usually the low energy high resolution collimators. The results of these uniformity controls are printed out and archived in a map.
Every bad result is taken care of, either by the company or by the engineers of our division.
If the results are really bad, the camera is shut down until the problem has been solved. Significant difference between these two scans result in the necessity for renormalization or detector replacement. This whole procedure takes approximately 25 minutes and uses the internal transmission source. A complete normalization procedure takes approximately 8 to 10 hours. The sources used in the normalization procedure include a plane source and a cylindrical uniform phantom.