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RAD100 CH8-9
Vocab
| Term | Definition |
|---|---|
| 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 its 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. |
| 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 beam. This device consists of four rectilinear, radiopaque blades that are adjustable to control the x-ray’s 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 (–452°F) to create a state of magnetic superconductivity |
| Diagnostic Yield | 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 | Also called a 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 |
| 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 digital 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; |
| Gamma Camera | A device used in radionuclide imaging to collect gamma photon emissions from patients creating nuclear medicine images |
| 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 a 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 |
| Longitudinal | Lengthwise, or along the long axis |
| MIMPS | Acronym for Medical Image Management and Processing System; 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) |
| 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 |
| 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 |
| 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 |
| 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 |
| Pyrex Glass | Special type of glass that 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 |
| 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 |
| RF Coil | Radio-frequency (RF) antennae that are used to transmit and receive RF frequencies, as an integral part of magnetic resonance (MR) image production |
| 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 |
| 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 is occurring |
| Remnant Radiation | All radiation exiting the patient during exposure and ultimately striking the receptor |
| Sequence | The choice of MR scanning protocols used in scanning patients. Sequences generally alter RF 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; 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 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 |
| Air Kerma | SI quantity used to measure energy transferred from radiation to matter, which may be at the surface of a patient’s or radiologic and imaging sciences professional’s body |
| ALARA | Mnemonic meaning to keep all radiation exposure as low as reasonably achievable |
| Becquerel (Bq) | Unit of radioactivity in the International System of Units, equal to one disintegration per second |
| Classic Coherent Scattering | Interaction with matter in which a low-energy photon (below 10 kiloelectron volts) is absorbed and released with its same energy, frequency, and wavelength but with a change of direction |
| Curie (Ci) | Unit of radioactivity defined as the quantity of any radioactive nuclide in which the number of disintegrations per second is 3.7 × 1010 |
| Exposure (X) | the amount of radiation delivered to a point. Measured in coulomb per kilogram. |
| Germ Cells | Cells of an organism whose function is to reproduce the organism (e.g., ovum, spermatozoa) |
| Gray (Gy) | Unit in the International System used to measure the amount of energy absorbed in any medium; 1 Gy = 100 radiation absorbed doses |
| International System (SI) of Units | System of units based on metric measurement developed in 1948 and having units used to measure radiation |
| Kiloelectron Volts (keV) | Units of energy equal to 1000 electron volts |
| Photoelectric Interaction | Interaction with matter in which a photon strikes an inner shell electron, causing its ejection from orbit with the complete absorption of the photon’s energy |
| Radiation | Forms of energy emitted and transferred through matter |
| Sievert (Sv) | Unit in the International System used to measure the dose equivalence, or biologic effectiveness, of differing radiations; 1 Sv = 100 rem |
| Somatic Cells | All of the body’s cells except germ cells |
| X-rays | Form of electromagnetic radiation traveling at the speed of light, possessing the ability to penetrate matter |
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hmarie94
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