NOMECLATURE

• 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
• 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 - 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 a digital 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
• 1. 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
• post processing - 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 recepto
• 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
• 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