radiology chapter 8

Automatic exposure control

The termination of an x-ray exposed base 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 enable 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 an integral part of the x-ray table located below the table top 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 good lines appear on image.

Cassette

Light proof holder for the image receptor it may be a computerized radiography plate or a wireless digital radiography panel

Cathode

Negative electrode of the xray tube

Collimator

An essential device designed to define the dimensions and direction of the x-ray beam. This device consist of four rectilinear, radiopaque blades that are adjustable to control the X-rays field size and shape

Cryogen

A cooling refrigerant that is used to reduce external temperatures to a very low level. This is required in high field MR systems and typically is accomplished using liquid helium to create a state of magnetic superconductivity.

Diagnostic yield

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

Dual emission xray absorptiometry (DEXA)

X-ray based technology that is used to assess bone density and bone health statistical calculations yield a T score and fracture risk assessment

CT number

Represent the numerical valuation of differential absorption that occurs as x-ray energy, penetrates tissue and a CT scan acquisition numbers represent the degree of linear attenuation of a data point as compared to a linear attenuation coefficient of water, which is zero

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.

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 digital capture technology

Flat panel detector

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

Fluoroscopy

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

Fluoroscope

Device used for dynamic, radiographic examinations of patient. Psychologic functionality consist of an x-ray tube and image interceptor aligned with each other in an orthogonal relationship.

Gamma camera

A device used in radio new Clyde imaging to collect gamma photon emissions from patient creating nuclear medicine images. Gamma cameras May have one or two detector heads and may rotate around the patient as a series of images are taken to create a single photo on a mission computed tomographic image

Gantry

Term used to express the equipment component that contains major technological components comprising a CT or MR scanner

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

Hounsfield unit

Numerical value used in the CT as a expression of the attenuation coefficient of a particular tissue or material x-ray energy penetrates

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 for 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 imaging often integrated into a larger hospital information system and radiology information system replacing the older term PACS

Orthogonal

A perpendicular relationship between the x-ray beam central rate and image receptor

Overhead tube crane OTC/3-D suspension

Mechanical support for suspending the x-ray tube and collimator assembly for the ceiling or the radio radiography room

Perfusion

The flow of blood or lymphatic fluids into an out of cells as a function of cell metabolism perfusion is critically important for normal cell and tissue physiology as it reflects the general health of tissues, and they’re capability to transport, oxygen nutrients and waste

Picture archival and communication system (PACS)

Computer network for the transmission viewing and archival storage of medical imaging often integrated into a larger hospital

Piezoelectric crystal

An integral component of the ultrasound transducer that converts the electrical energy into sound energy and various frequencies above the human range

Positive beam limitation (PBL)

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

Post processing

Manipulation of medical imaging 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 horoscope Milli amperage characteristics can be modified to maintain optimum image quality at a lower radiation dose

Pyrex glass

Specific glass type that can withstand very high temperatures from the x-ray tube

Primary barrier

A receptor of X radiation that intercepts the primary beam and prevents exposure, if not interlock with the central ray of the x-ray beam

Quantum mottle

An undesirable image quality characteristic that shows images graininess, and a loss of visual acuity. Most often the result of exposure to the receptor.

RF coil

Radio, frequency a 10 a that are used to transmit and receive radio frequency’s , As an integral part of magnetic resonance image production

Radiolucent

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

Radiopaque

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

Radionuclide

Radioactive substance that spontaneously emits nuclear particles and or gamma radiation; chemically attached to a carrier material to assess tissue perfusion through the detection of gamma emissions

Real time images

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

Remnant radiation

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

Sequence

The choice of MR scanning protocols used and scanning patients. Sequences, generally alter radio frequency, signal, pulse amplitude, and duration.

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

Teletherapy

Administration of the 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

Transducer

Handheld device used by sonographers to emit and receive ultrasound energies

Transverse

Placed cross wire situated at right angles to the long axis of a part

Trendelenburg Tilt

Table till 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 measure

Vertical

Perpendicular to the plane of the horizon

Xray tube

Device that produces x-rays

X ray tube head

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