Medical Assistant Chapter 52: Radiology Basics

automatic exposure control (AEC)

Terminates the exposure time when a certain quantity of radiation has been detected at the Image receptor.

bremsstrahlung radiation

Radiation that is created when an electron enters the tungsten anode of the x-ray tube, misses the tungsten electrons, and gets very near the nucleus.

Bucky

Contains a movable grid device that absorbs scatter radiation and also contains the image receptor.

central ray (CR)

The center of the x-ray beam and perpendicular to the long axis of the x-ray tube.

characteristic radiation

Radiation that is created when an electron enters the tungsten anode of the x-ray tube and knocks out a K-shell electron.

collimation

The method of restricting and confiding the x-ray beam to a given area.

computed radiography

A cassette-based digital imaging system where the image of the body part is obtained using storage phosphor plate.

digital radiography (DR)

Cassetteless imaging system where the phosphor is bonded to a flat panel detector or the system converts x-ray energy directly to an electronic signal.

distortion

The differences between the actual subject and its radiographic image.

energy

The ability to do work.

exposure indicator (EI)

A numeric value indicating the quantity of ionizing radiation received by a digital radiographic image receptor; also called an exposure index.

fog

The unwanted image exposure caused by scatter radiation.

generator

Delivers the electrical power to the x-ray tube and permits the selection of x-ray energy, x-ray quantity, and exposure time.

image receptor (IR)

The device that receives the energy of the x-ray beam and forms the image of the body part.

ionizing radiation

Radiation that, when passing through the body, produces positively and negatively charged particles.

kilovolts peak (kVp)

The unit of measure used to assess the voltage; controls the penetrating power of the x-ray beam.

line focus principle

The relationship between the actual focal spot on the anode surface and the effective focal spot size.

matter

Anything that occupies space and has shape or form.

object-to-image receptor distance (OID)

The distance between the subject and the image receptor.

primary radiation

The radiation that leaves the tube.

radiation field

The squared area of the x-ray beam that strikes the patient and x-ray table.

radiation protection

The measures taken to safeguard patients, personnel, and the public from unnecessary exposure to ionizing radiation.

scatter radiation

Radiation from the primary beam that is randomly scattered within or outside of the body.

source-to-image-receptor distance (SID)

The distance between the tube target and the image receptor.

thermionic emission

Electrons begin to "boil effect," when the filament is heated.

x-ray tube

The source of x-rays; the x-rays are formed within the x-ray tube.