ABSTRACT
(Diagnostic Radiology) Sometimes image quality parameters and related dose parameters can be linked in a formula, presenting the quality as a single figure. This new empirical figure is an imaging performance parameter, known as Q factor or Q value. However it is not an absolute figure, as it often depends on additional parameters, such as type of test object, x-ray system parameters, etc. For example, one such Q value, used for the evaluation of some CT scanners, includes a formula incorporating the 50% value of the MTF, the percentage of image noise, the nominal slice thickness and the dose in water.
