A Case Study into the Effect of Radiographic Factors on Image Quality and Dose for a Selenium Based Digital Chest Radiography System

Thoravision, the first commercially available digital radiography system utilising amorphous selenium, has been evaluated from both clinical and physical perspectives. The advent of digital radiography systems has made the optimisation of both image quality and dose an important problem. Initial studies, using the manufacturer's recommended factors, demonstrated that the image quality, measured both objectively and subjectively, was significantly superior to conventional screen-film images. However, some questions still remained regarding the system's performance. A second study using alternative factors showed that the Thoravision always produced acceptable diagnostic images, regardless of the factors, and there are advantages to using lower kVp, objective measurements of image quality confirm this. It is clear that no single set of radiographic factors and image processing algorithms will produce optimised images for every patient and further elucidation of the problem is required. The difference between acceptable and a good clinical image is also highlighted and the implications discussed. (author)