Glossary
The glossary is an alphabetical list of defined terms or words specifically found in the ASRT Practice Standards for Medical Imaging and Radiation Therapy. The terms or words have meaning that might not be general knowledge. The definitions are formulated using evidentiary documentation and put into place following extensive review and subsequent approval. The glossary is not all-inclusive. New terms and new usage of existing terms will emerge with time and advances in technology.
AAPM – American Association of Physicists in Medicine
ACR – American College of Radiology
adverse event – Any undesirable experience associated with the use of a medical product in a patient.
AI – artificial intelligence
ALARA – Acronym for “as low as (is) reasonably achievable,” which means making every
reasonable effort to maintain exposures to radiation as far below the dose limits as practical,
consistent with the purpose for which the licensed activity is undertaken, while taking into
account the state of technology, the economics of improvements in relation to state of
technology, the economics of improvements in relation to benefits to the public health and safety
and other societal and socioeconomic considerations, and in relation to the use of nuclear energy
and licensed materials in the public interest. The ASRT recognizes the concept of ALARA to
include energies used for magnetic resonance and sonographic imaging.
anatomic (anatomical) landmarks – Bones or other identifiable points that are visible or
palpable and indicate the position of internal anatomy.
appropriate action plan – Encompasses the initial, current or revised action plan.
archive (archival) – The storage of data in either hard (film) or soft (digital) form.
ARDMS – American Registry for Diagnostic Medical Sonography
ARRT – American Registry of Radiologic Technologists
artifact – Extraneous information on the image that interferes with or distracts from image quality.
ASRT – American Society of Radiologic Technologists
authorized user – A physician, dentist or podiatrist who meets the requirements as defined by the United States Nuclear Regulatory Commission.
beam-modification devices – Devices that change the shape of the treatment field or distribution of the radiation at (tissue) depth.
brachytherapy – A method of treatment that involves the temporary or permanent placement of radiation source(s) (isotopic or electronic) inside or immediately adjacent to a tumor-bearing region.
CCI – Cardiovascular Credentialing International
change management – Systematic approach to preparing for, implementing and sustaining a change in process.
clinical – Pertaining to or founded on actual observations and treatments of patients.
clinically competent – The ability to perform a clinical procedure in a manner that satisfies the demands of a situation, as assessed and documented by a qualified individual.
compounding medication – The combining, mixing, pooling or otherwise altering of a conventionally manufactured drug in response to or anticipation of a medication order.
compounding radiopharmaceutical – The combining, mixing, pooling or otherwise altering of
a conventionally manufactured radiopharmaceutical or synthesizing/formulating a
radiopharmaceutical from bulk drug substances and radionuclides.
contrast media – A substance administered during a medical imaging procedure for the purpose of enhancing the contrast between an internal structure or fluid and the surrounding tissue.
cropping – The process of selecting and removing a portion of the image.
custom blocks – Devices designed to shape the radiation field.
DICOM – Acronym for “Digital Imaging and Communications in Medicine.” The DICOM
standards are a complex set of instructions to exchange and present medical image information.
dose distribution – Spatial representation of the magnitude of the dose produced by a source of radiation. It describes the variation of dose with position within an irradiated volume.
dose pooling – Combining unit doses of a radiopharmaceutical to meet the dosage requirements of a single patient.
dosimetric calculations – – Computation of treatment unit settings, monitor units, treatment times and radiation doses to anatomical areas of interest.
ECG – – electrocardiogram
educationally prepared – The successful completion of didactic and clinical education
necessary to properly perform a procedure in accordance with accepted practice standards.
electronic masking – Electronic collimation or cropping of the digital radiographic image that occurs during postprocessing of the acquired image and does not alter the size of the irradiated field.
FDA – U.S. Food and Drug Administration
GRADE – Grading of Recommendations Assessment, Development and Evaluation
HIPAA – Health Insurance Portability and Accountability Act of 1996
HQCC – Healthcare Quality Certification Commission
hybrid imaging – – The combination of imaging technologies that allows information from
different modalities to be presented as a single set of images.
image-guided radiation therapy – A process of using various imaging technologies to localize the target and critical tissues and, if needed, reposition the patient just before or during the delivery of radiotherapy.
imaging technologies – Technologies using ionizing and nonionizing radiation to visualize
physiological processes, internal structures and fiducial markers, both anatomical and nonanatomical.
immediate use – Dose preparation, including one made using appropriate and necessary
deviation, and/or the dispensing of a sterile radiopharmaceutical specific for a single patient.
immobilization device – Device that assists in maintaining or reproducing the position while limiting patient movement.
initial observation – Assessment of technical image quality with pathophysiology correlation communicated to a radiologist.
interpretation – The process of examining and analyzing all images within a given procedure and integration of the imaging data with appropriate clinical data in order to render an impression or conclusion set forth in a formal written report composed and signed by a licensed practitioner.
interventional procedures – – Invasive medical imaging guidance methods used to diagnose
and/or treat certain conditions.
ISCD – International Society for Clinical Densitometry
JRC-DMS – Joint Review Committee on Education in Diagnostic Medical Sonography
least significant change ‒ The least amount of bone mineral densitometry change that can be
considered statistically significant.
licensed practitioner – A medical or osteopathic physician, chiropractor, podiatrist or dentist who has education and specialist training in the medical or dental use of radiation and is deemed competent to perform independently or supervise medical imaging or radiation therapy procedures by the respective state licensure board
MDCB – Medical Dosimetrist Certification Board
medical physicist – An individual who is competent to practice independently in the safe use of x-rays, gamma rays, electron and other charged particle beams, neutrons, radionuclides, sealed radionuclide sources, ultrasonic radiation, radiofrequency radiation and magnetic fields for diagnostic and therapeutic purposes. An individual is considered competent to practice in the field of medical physics if the individual is certified by the appropriate recognized certification organization.
medication – Any chemical substance intended for use in the medical diagnosis, cure, treatment or prevention of disease.
minimal sedation (anxiolysis) – A drug-induced state during which patients respond normally to verbal commands. Although cognitive function and coordination may be impaired, ventilatory and cardiovascular functions are unaffected.
moderate sedation – A drug-induced depression of consciousness during which patients
respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate. Cardiovascular function is usually maintained.
molecular imaging – A noninvasive, diagnostic imaging technology that enables visualization, characterization and measurement of biologic processes at the molecular and cellular levels.
Molecular imaging techniques may be applied to computed tomography, magnetic resonance, nuclear medicine, optical imaging, PET-CT, sonography and spectroscopy.
monitor units – Unit of output measure used for linear accelerators, sometimes indicated with the abbreviation MU. Accelerators are calibrated so that 1 MU delivers 1 cGy for a standard reference field size at a standard reference depth at a standard source to calibration point.
MQSA – Mammography Quality Standards Act
MR Level 2 Personnel – Individuals who have completed more extensive education in broad MR safety issues related to all MR energy fields.
NECS – National Education Curriculum for Sonography
NMTCB – Nuclear Medicine Technology Certification Board
noninterpretive fluoroscopic procedures – Use of fluoroscopic imaging under the direction of a licensed practitioner for purposes other than interpretation.
normal tissue tolerance – Radiation tolerance levels of healthy organs near or within the
radiation treatment fields.
NRC – U.S. Nuclear Regulatory Commission
panning – Movement of the procedure table during image production to maintain visualization of an anatomic region of interest.
personal radiation monitoring devices – Devices designed to be worn or carried by an
individual for the purpose of measuring the dose of radiation received.
physics survey – Performing equipment testing, evaluating the testing results and completing a formal written report of results. The written survey report, validated by a medical physicist, contains sufficient information to document that each test was conducted according to local, federal or state requirements and includes an assessment of corrective actions and recommendations for improvements
point-of-care testing – Medical diagnostic testing performed outside the clinical laboratory in close proximity to where the patient is receiving care (e.g., blood sugars, creatinine).
postprocessing – Computerized processing of data sets after acquisition to create a diagnostic or therapeutic image.
procedure – Specific course of action intended to result in an imaging study, treatment or other outcome.
processing – Manipulation of the raw data just after acquisition.
protocol – The plan for carrying out a procedure, scientific study or a patient’s treatment regimen.
quality assurance – Activities and programs designed to achieve a desired degree or grade of care in a defined medical, nursing or health care setting or program. Sometimes indicated with the abbreviation QA.
quality control – The routine performance of techniques used in monitoring or testing and
maintenance of components of medical imaging and radiation therapy equipment. This includes the interpretation of data regarding equipment function and confirmation that corrective actions are/were taken. Sometimes indicated with the abbreviation QC.
radiation oncologist – A physician who specializes in using radiation to treat cancer.
radiation protection – Prophylaxis against injury from ionizing radiation. The only effective preventive measures are shielding the operator, handlers and patients from the radiation source; maintaining appropriate distance from the source; and limiting the time and amount of exposure.
radioactive material – A substance composed of unstable atoms that decay with the
spontaneous emission of radioactivity. Includes radiopharmaceuticals, unsealed sources (open, frequently in liquid or gaseous form) and sealed sources (permanently encapsulated, frequently in solid form).
radiobiology – The study of the effects of radiation on living organisms.
radiography – The process of obtaining an image for diagnostic examination using x-rays.
radiotheranostics – The use of radionuclides for the paired imaging and therapy agents.
remote procedure – Operator control of image acquisition from a physical location that is different from the patient.
RSO – Radiation Safety Officer
scholarly activity – Activities that systematically advance the teaching, research and practice of the medical imaging and radiation therapy profession through scientific investigation, presentation, and publication.
setup – Arrangement of treatment parameters used in preparation for delivering radiation
therapy; includes patient positioning data, field alignment information and equipment configurations.
shuttering – A postprocessing technique that may be used to eliminate ambient light around an image for the sole purpose of improving the quality of the displayed image. It should not be used as a substitute for insufficient collimation of the irradiated field.
simulation – A process using imaging technologies to plan radiation therapy so that the target area is precisely located and marked; the mockup procedure of a patient treatment with medical imaging documentation of the treatment portals.
SNMMI – Society of Nuclear Medicine and Molecular Imaging
static – Any medical image that is fixed or frozen in time.
superficial radiation therapy – Treatment with x-rays produced at potentials ranging from 40-150 kV.
supervising radiologist – A board-certified or board-eligible radiologist who oversees duties of the radiologist assistant and has appropriate clinical privileges for the procedure performed by the radiologist assistant.
theranostics – The systematic integration of targeted diagnostics and therapeutics.
timeout – Preprocedural pause to conduct a final assessment that the correct patient, site and procedure are identified.
tolerance levels (doses) – The maximum radiation dose that may be delivered to a given
biological tissue at a specified dose rate and throughout a specified volume without producing an unacceptable change in the tissue.
treatment calculations – See dosimetric calculations.
treatment field (portal) – Volume of tissue exposed to radiation from a single radiation beam.
treatment planning – The process by which dose delivery is optimized for a given patient and clinical situation. It encompasses procedures involved in planning a course of radiation treatment, including simulation through completion of the treatment summary
treatment record – – Documents the delivery of treatments, recording of fractional and
cumulative doses, machine settings, verification imaging and the ordering and implementation of prescribed changes.
T-score – Number of standard deviations the individual’s bone mineral density is from the
average bone mineral density for gender-matched young normal peak bone mass.
USP – United States Pharmacopeia
vascular access device – Apparatus inserted into the peripheral or central vasculature for
diagnostic or therapeutic purposes.
vascular closure device ‒ Active or passive medical devices used to achieve hemostasis after a
cardiovascular or endovascular procedure that requires catheterization.
venipuncture – The transcutaneous puncture of a vein by a sharp rigid stylet or cannula carrying a flexible plastic catheter or by a steel needle attached to a syringe or catheter.
verification images – – Images produced to confirm accurate treatment positioning and accurate treatment portals.
Z-score – Number of standard deviations the individual’s bone mineral density is from the
average bone mineral density for age- and gender-matched reference group.