Process of conversion of continuous (analog) signals, such as the detected ultrasound or MRI signal (voltage), into numbers. This is carried out with an analog to digital converter.
There are two kinds of discretization involved: the voltage is only measured (sampled) at particular discrete times and only voltages within a particular range and separated by a particular minimum amount can be distinguished. Voltages beyond this range are said to exceed the dynamic range of the digitizer.

(ADC) A system that receives analog input data and produces digital values at its output. Analog to digital converters are used by the ultrasound scanner to convert the received signal into a format more compatible with the computer systems.
Ultrasound front-end-systems as well as many others sophisticated electronic systems use these analog signal processing components in connection with e.g., low-noise amplifier (LNA), and time gain compensation amplifier (TGC) as key elements in determining the overall system performance.

See also Digital to Analog Converter, and Digitization.

(DICOM) DICOM is the industry standard for transferral of radiologic images and other medical information between computers. Patterned after the Open System Interconnection of the International Standards Organization, DICOM enables digital communication between diagnostic and therapeutic equipment and systems from various manufacturers.
The DICOM 3.0 standard evolved from versions 1.0 (1985) and 2.0 (1988) of a standard developed by the American College of Radiology (ACR) and National Electrical Manufacturers Association (NEMA). To support the implementation and demonstration of DICOM 3.0, the RSNA Electronic Communications Committee began to work with the ACR-NEMA MedPacs ad hoc section in 1992.
Also Picture Archiving and Communication Systems (PACS), which are connected with the Radiology Information System (RIS), use commonly the DICOM standard for the transfer and storage of medical images.

See also Digitization.