Question

Regarding the post-processing of digital radiography images: 

a. Irregular shading across the image field is an irreversible artefact 

b. Defective pixels within the matrix may not alter the final image quality 

c. The wide dynamic range of unprocessed data can result in loss of image quality 

d. Auto-ranging is operator dependent 

e. Auto-ranging improves spatial resolution

Answer 1

a. False. This refers to the variation in X-ray sensitivity, which may occur across the detector and be seen in the resultant image. This can be adjusted using gain calibration (so is not irreversible). 

b. True. This is compensated for by a process known as flat-field calibration. However, if there are a significant number of defective pixels, then image quality/ accuracy may be compromised. 

c. True. If data are unprocessed, then the imaging display device may not be able to demonstrate the full range of intensities obtained. This is overcome by a process known as auto-ranging, which processes the data to display only the most important part of the response range relevant to the particular examination performed. 

d. False. It is an automatic process that is performed by software once details of the projection performed have been entered into the system, e.g. chest radio graph. 

e. False.