RADT 101: Ch 8 TEST 2

Medical Imaging Equipment

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 a user-selectable and its accuracy is position-dependent

Auto-tracking

A feature of modern x-ray 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, and it 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

• can be CR or DR

Cathode

negative electrode of the x-ray tube

Collimator

An essential device designed to define the dimensions and fdirection of the x-ray bean

• consists of four rectilinear, radiopaque blades that are adjustable to contorl the x-ray field size and shape

• may be operated manually or automatically

cryogen

a cooling refrigerant that is used to reduce external temperatures to a very low leve

• required in high field MR systems and typically is accomplished using liquid helium to create a astate of magnetic superconductivity

Diagnostic Field

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

DXA

Acronym for Dual Emission X-ray Absorptiometry

• x-ray based technology that is used to assess bone density and bone health

• statistical calculations yield a T-score and fracture risk assessment (FRAX)

CT Number

• aka Hounsfield Unit (HU)

• CT numbers represent the numerical valuation of differential absorption that occurs as x-ray energy penetrates tissue in a CT scan acquisition

• CT numbers represent the degree of linear attenuation of a data point as compared to the linear attenuation coefficient of water, which is (0)

• can range from +1000 to -1000

Digital Imaging

Acquisition of static imagines in an electronic fashion to create an electronic data set

• conversion of images to a digital formation for image manipulation, enhancement, archival, and networking

Diode

Electronical component that posseses 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 (FPD)

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

Fluoroscope

Device used for dynamic radiographic examination 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 pt depending upon system design

Gamma Camera

A device used in radionuclide imaging to collect gamma photon emissions from patients creating nuclear medicine images

• gamma cameras may have one or tow detector heads and may rotate around the patient as series of images are taken to create a single photon emission computed tomographic (SPECT) imaage

Fluoroscopy

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

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 (HU)

Numerical value used in CT as an expression of the attenuation coefficient of an particular tissue or material x-ray energies penetrate

• considered a vital feature of ct image interpretation and also referred to as CT number

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

MIMPS

acronym for medical image management and processing system

• computer network fro the transmission,, viewing, and archival storage of medical images

• integrated into hospital information system (HIS) and radiology information system (RIS)

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

Perfusion

The flow of blood or lymphatic fluids into and out of cells as a function of cell metabolism

• is critically important for normal cell and tissue physiology as it reflects the general health of tissues and their capacity to transport oxygen, nutrients, and waste products

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 systems (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 crystals are convert sound energy into electrical signals that become the sonographic image

Positive Beam Limitation (PBL)

Form af automatic x-ray beam collimation of field size is no larger than 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 mod 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

Special type of glass that can withstand very high temperatures from the x-ray tube anaode

Primary Barrier

A receptor of x-radiation that intercepts the primary bean and prevents exposure if not interlocked with the central ray of the x-ray bean

• fluoroscopy the fluoroscopic digital or image intensifier tube are primary barriers

RF Coil

Radio-frequency (RF) antennae that are used to transmit and receive RF frequencies as an integral part of magnetic resonnance (MR) image production

Real-Time Images

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

Sequence

The choice of MR scanning protocols used in scanning patients

• sequences generally alter RF signal pulse amplitude and duration

• an MR sequence can be likened to radiographic exposure technique selection

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

Teletherapy

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

Transducer

Hand-held device used by sonographers to emit and receive ultrasound energies in the production of sonographic images

Transverse

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

Trendelenburg tilt

Table tilt angel in which the patient’s head 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 plan of the horizon

x-ray tube

device that produces x-rays

X-ray tube head

equipment consisting of the c-ray tube, collimator, and operator controls

• permits manipulation of the x0ray tube in many directions for proper positioning