A developing agent is a chemical, usually phenidone, hydroquinone or metole, which reduces exposed silver ions to atomic silver to visualize an image on a film.

See also X-Ray Film, Film Processor, Activator, Clearing Agent, Developer and Fixer.

(DRL) The diagnostic reference level is a patient dose-related quantity per x-ray procedure or image. The diagnostic reference level is essentially a guide and the first step in the management of patient doses. Dose descriptors can also be used to compare local doses to national reference doses and reviews of local practice if consistently exceeded.

Diaphanography is a noninvasive breast imaging technique used in diagnosis of breast disease. The breast is illuminated with low intensity light and the transmission pattern of red and near-infrared radiation is detected. After amplification and reconstruction, the images are displayed on a monitor.
Results from diaphanography tend to show lower sensitivities and specificities than are found in diagnostic mammography studies. Light scanning (diaphanography and transillumination) is not recommended for screening or diagnostic evaluation of the breast.

The display matrix is the matrix in the displayed image and can be equal to or larger than the reconstruction matrix size due to interpolation procedures. This array of rows and columns of pixels is typically between 512 x 512 and 1024 x 1024.

Electronic noise decreases the image quality. There are various noise sources in any electronic system, including Johnson noise, shot noise, or thermal noise. Electronic noise can be caused by vibrations of any of the hardware components, especially the rotational components of a CT scanner or power fluctuations.