ADC

(analog-to-digital converter) converts image information
into numerical data

AEC

automatic exposure control (ionization chamber located
between the patient and the image receptor)

algorithm

mathematical formula used by the computer to
construct the radiographic image

anode

positive electrode in the x-ray tube

APR; APT

anatomically programmed radiography;
anatomically programmed technique; exposure technique is
set by the radiographer by choosing the proper anatomic part
and projection on the control panel

artifact

an unwanted marking on a radiographic image

automatic collimation

also known as positive beam limitation
(PBL); the ability of the radiographic equipment to collimate
automatically the x-ray beam to the same size as the image
receptor resting in the Bucky tray

bit binary digit

either 1 or 0; the computer’s unit of information

bit depth

the number of shades of gray available within a pixel

blur

effect of motion on the radiographic image

brightness, image brightness

the amount of light coming from the monitor on which the radiographic image is displayed

Bucky

short for Poer-Bucky diaphragm; a moving grid used to remove scaer radiation from the remnant beam, which can cause fog on the image receptor

cassette

container used for holding the imaging plate in
computed radiography (CR)

cathode

negative electrode in the x-ray tube

collimator

box-like structure attached to the x-ray tube containing lead shutters that limit the x-ray beam to a specific area of the body

contrast media

solutions or gasses introduced into the body to
increase the scale of contrast, making more detail visible;
negative contrast medium is air; positive contrast media are
barium and iodine

computed radiography (CR)

digital radiographic imaging using a cassette containing an imaging plate

contrast

the visible difference between two selected areas of
brightness in the radiographic image; contrast allows detail to
be visible

contrast resolution

the smallest change in signal that can be detected by the image receptor

DAP

dose area product, a measure of the total radiation
exposure to the patient, extrapolated from the dose in the air
just above the patient

DICOM (digital imaging and communications in medicine)

a standard protocol used for blending a picture archiving and
communications system and various imaging modalities

direct radiography (DR)

uses fixed detectors that directly communicate with a computer

distortion

misrepresentation of the size or shape of the object as recorded in the radiographic image

dynamic range

the ability of an image receptor to capture the x-ray photons leaving the patient

exposure indicator

describes the status of the exposure and diagnostic value of the digital image

fluoroscopy

“live action” imaging when the x-ray beam is on,
creating images of the body as it functions and displaying
those images on a monitor

focal spot (focal track)

area of the anode in the x-ray tube from which x-rays emanate

grid

device that is placed between the patient and the image
receptor that absorbs scatter radiation exiting the body

HIS

hospital information system

HL7

health level seven, an international standard for communicating medical information

histogram

graphic display of the distribution of pixel values in adigital image

image receptor (IR)

any device or medium that captures the remnant beam

imaging plate (IP)

plate that is coated with photostimulable
phosphors that absorb the photon energies exiting the patient;
located inside a computed radiography (CR) cassette

kVp peak kilovoltage

that is applied to the x-ray tube, which
determines the wavelength of the x-ray beam and its ability to
penetrate the body, impacting the overall contrast of the
radiographic image

lead aprons

coverings worn by radiographers who are in a
radiographic or fluoroscopic room with the x-ray beam
turned on; also required to be worn for radiation protection
when performing portable radiography; the lead absorbs
most of the scatter radiation that strikes the apron

mAs (milliampere-seconds)

the product of milliamperage and time; mA is the current that is passed through the x-ray tube, whose energy is then converted to x-rays when it strikes the anode; it determines the number of x-rays produced and,
consequently, the overall exposure striking the image receptor; radiation exposure to the patient is directly proportional to the mAs used

matrix

digital image that is made up of rows and columns of data

mobile radiography portable radiography

imaging patients in locations other than an x-ray room, such as the patient’s room or operating room (see surgical radiography); because of presence of scatter radiation, the radiographer is required to wear a dosimeter and lead apron

OID (object-to-image receptor distance)

distance from the part being examined to the image receptor

PACS

picture archiving and communications system

pixel

picture element; the smallest component of a matrix

postprocessing

digital manipulation of a radiographic image after its acquisition by the computer

PSP (photostimulable phosphor)

coating on the imaging plate of a computed radiography cassette

radiographic image x-ray

image as viewed on a monitor after acquisition

radiographic position

specific position of the body or body part in relation to the table or image receptor

radiographic projection

path the x-ray beam takes as it passes through the body; described as if the body is in the anatomical position

radiographic view

term used to explain how the image receptor sees the body image; the opposite of the radiographic projection

remnant beam (exit radiation)

x-ray beam that exits the patient; is made up of image-forming rays and scatter radiation

RIS

radiology information system

scatter radiation

x-rays emanating from the patient in divergent paths rather than straight to the image receptor; the source of the radiographer’s occupational dose, requiring the wearing of a lead apron and dosimeter for fluoroscopy and mobile radiography

spatial resolution

the sharpness of the structural edges in the radiographic image; the smallest detail that can be detected

SID (source-to-image receptor distance)

distance from the source of radiation (x-ray tube anode) to the image receptor

SOD (source-to-object distance)

distance from the source of radiation (x-ray tube anode) to the part being examined

surgical radiography

radiographic procedures performed by the radiographer in the operating room, usually using a C-arm (portable fluoroscope)

time, distance, shielding

the three cardinal principles of radiation protection; least amount of time exposed, greatest distance from the source of radiation, use of lead or other
barriers to shield

voxel

volume element; section of tissue represented by a pixel

window

level midpoint of densities in a digital image; used to adjust digital image brightness

window

width adjusts contrast of the digital image

workstation (radiologist or radiographer)

location of the monitor on which radiographic images are displayed

x-ray

a form of electromagnetic radiation at wavelengths that
can penetrate matter