Ch. 8 Key Terms

Automatic Exposure Control (AEC)

The termination of an x-ray exposure based upon optimum x-ray energy being sensed by a solid-state detector. This is user-selectable and it’s accuracy is position-dependent

Auto-tracking

A feature of modern x-ray systems that enables simultaneous vertical movement of an upright image receptor and overhead x-ray tube

Anode

Positive electrode of the x-ray tube

Bucky Mechanism

Grid that is an integral part of the x-ray table, located below the tabletop and above a cassette receptor tray. It decreases the amount of scatter radiation reaching the image receptor, and can improve image quality. It also moves during exposure so that no grid lines appear on the image

Cassette

Lightproof holder for the image receptor. It may be a computerized radiography (CR) plate or a wireless, digital radiography (DR) panel

Cathode

Negative electrode of the x-ray tube

Collimator

An essential device designed to define the dimensions and direction of the x-ray beams. This device consists of four rectilinear, radiopaque blades that are adjustable to control the x-ray’s field size and shape. It may be operated manually or automatically.

Diagnostic Yield

The amount of clinically useful, diagnostic information that is produced by a medical imaging modality.

Digital Imaging

Acquisition of static images in an electronic fashion to create an electronic data set; conversion of images to a digital format for image manipulation, enhancement, archival, and networking; often referenced as DR (digital radiography)

Diode

Electrical component that possesses polarity with a negative and positive terminal

DR Panel

Common term for a flat-panel digital image receptor using either indirect or direct capture technology

Flat-Panel Detector (FPD)

Type of digital detector employing amorphous silicon or selenium material bonded with thin-film transistor technology for digital image creation and amplification.

Fluoroscope

Device used for dynamic radiographic examinations of patient physiologic functionality; consists of an x-ray tube and image receptor, aligned with each other in an orthogonal relationship; the x-ray tube and receptor may be above or below the patient depending upon system design

Fluoroscopy

Examination by means of the fluoroscope, employing image intensification or a flat panel detector

Goniometer

Angulation scale incorporated into the x-ray tube-head assembly to indicate the degree of x-ray tube angle, relative to the image receptor

Latent Image

Invisible image created electronically after x-ray exposure and before image processing

Linear Accelerator

A major piece of equipment used for radiation therapy to administer x-ray or electron energies in the treatment of malignant tumors

Longitudinal

Lengthwise, or along the long axis

Medical Image Management and Processing System (MIMPS)

Computer network for the transmission, viewing, and archival storage of medical images; often integrated into a larger hospital information system (HIS) and radiology information system (RIS); replacing the older term PACS

Orthogonal

A perpendicular relationship between the x-ray beam central ray (CR) and image receptor

Overhead Tube Crane OTC/3-D Suspension

Mechanical support for suspending the x-ray tube and collimator assembly from the ceiling of the radiography room

Picture Archival and Communication System(PACS)

Computer network for the transmission, viewing, and archival storage of medical images; often integrated into a larger hospital information system (HIS) and radiology information system (RIS)

Piezoelectric Crystal

An integral component of the ultrasound transducer that converts electrical energy into sound energies of various frequencies above the human audible range. These ____ also convert sound energy (echoes) into electrical signals that become the sonographic image

Positive Beam Limitation (PBL)

Form of automatic x-ray beam collimation of field size ensuring that the x-ray exposure field is no larger that the receptor size

Postprocessing

Manipulation of medical images after they have been acquired through x-ray exposure in order to improve image quality and diagnostic yield

Pulsed Progressive Fluoroscopy (PPF)

A fluoroscopic mode in which the fluoroscopic milli-amperage (mA) characteristics can be modified to maintain optimum image quality at a lower radiation dose; mA traits such as pulse height, pulse width, pulse rate and pulse interval can be altered to optimize image quality

Pyrex Glass

Can withstand very high temperatures from the x-ray tube anode

Primary Barrier

A receptor of x-radiation that intercepts the primary beam and prevents exposure if not interlocked with the central ray of the x-ray beam. In fluoroscopy, the fluoroscopic digital panel or image intensifier tube are _______.

Quantum Mottle

An undesirable image quality characteristic that shows image graininess and a loss in visual acuity; most often the result of underexposure to the receptor

Radiolucent

Describes a material that easily transmits x-ray energy with very little absorption

Radiopaque

Describes a material that absorbs x-ray energy, predominantly through the photoelectric effect

Real-Time Images

Images in which dynamic patient motion is visualized instantly as fluoroscopic imaging is occurring

Remnant Radiation

All radiation exiting the patient during exposure and ultimately striking the receptor

Soft Copy

Visualization of x-ray images using a video monitor for display and interpretation

Spot Image

Equipment that permits the acquisition of static images during a dynamic fluoroscopic examination; images acquired digitally and stored electronically

Telethrerapy

Administration of therapeutic dosages of x-radiation or electrons to patient anatomy from a distance, in order to treat malignant tumors

Tether

Electrical wire connection between a digital detector and the x-ray generator and computer

Transverse

Placed crosswise; situated at right angles to the long axis of a part

Tredelenburg Tilt

Table tilt angle in which the patient’s head and thorax are lower than their legs

Tube Angulation

Pivoting the tube at the point where it is attached to its support; measured and displayed in degrees

Vertical

Perpendicular to the plane of the horizon

X-ray Tube

Device that produces x-rays

X-Ray Tube Head

Equipment consisting of the x-ray tube, collimator, and operator controls; permits manipulation of the x-ray tube in many directions for proper positioning