Relation between the patient dose and the image quality for commercial imaging devices

Luis Alberto Vazquez Quino, University of Texas at El Paso


The modality of computed radiography (CR) is every day more used in hospitals as a regular image technique. The knowledge about how much dose is necessary to produce an image and the quality of the image in function of that dose is unknown. The aim of this work is to probe the hypothesis that with higher doses the quality of the image is better. In this work the physics and mathematical principles of computed radiography are presented and the mechanism of how CR works and the parameters to measure the quality of an image. A procedure in order to obtain a quantitative estimation of the image quality is presented. This procedure is based in the calculation of the modulation transfer function (MTF) of the images. Two methods to calculate the MTF are presented; a traditional and accepted method (Grid Phantom Method GP) and a new method called Gaussian Fitting Method (GF) are used to calculate the MTF and are compared. Two different system of CR are used to get different images with different doses used and the analysis of this two system (Philips-Agfa and Varian-Agfa) are presented. The result of this comparison is presented and the estimation of the noise in the images is calculated. The results obtained for the quality of the image and the noise will help to the develop of a procedure to determine at what dose the quality of the image is desired and to help to the radiologists to make a decision about what dose use depending of what part of the body is going to be taken a radiography.

Subject Area

Medical imaging|Nuclear physics|Biophysics

Recommended Citation

Vazquez Quino, Luis Alberto, "Relation between the patient dose and the image quality for commercial imaging devices" (2008). ETD Collection for University of Texas, El Paso. AAI1456734.