Dark Noise

               As technology is getting more and more advanced, more beneficial equipments are being developed in diagnostic imaging.  Examples like DR and CR are huge improvements compare to the film screen in the past.  However, having good quality equipments does not mean they do not need to do any testings or maintenance.  In fact, in order to keep up the performance of these advanced equipments, regular checkups are required and that is the purpose of quality control. Dark Noise is a quality control method for CR readers. It is a simple and fast control test because it only requires one to erase a cassette and then process it without exposure.  A cassette and a CR processing station are the materials that one needs to perform this test.              

The purpose of a Dark Noise test is to give indication of system noise.  This is extremely important to diagnostic imaging because if a CR reader is not working properly, there would be artifacts showing up on the image and these artifacts would lead to inaccurate diagnosis and increase patient dose.  Therefore, a dark noise test should be done once in a while to ensure the CR reader is performing properly.  Another reason that this test is important is because it also ensures the uniformity of the CR reader.  Although there are other quality control test that would test the uniformity of the CR reader, this test can also ensure the reader is working in a consistent manner. 

The image above is a picture that i took during the lab. It is the result of the dark noise test. As one can see, there are no artifacts at all and the exposure index is 10. According to the guideline for safety, the exposure index of GE should not be exceeding 80.Thus, our CR reader passed the Dark noise test.