ABR NMP key terms

A system in which a long-lived parent radionuclide decays into a shorter-lived daughter that is periodically eluted for clinical use, such as molybdenum-99 yielding technetium-99m.

A condition in which a daughter radionuclide decays with a half-life shorter than its parent, so both activities decline together at the parent's rate after an initial buildup period.

A state in which a parent radionuclide has a half-life so much longer than its daughter that the daughter's activity approaches and holds the parent's activity over practical times.

The fraction of available daughter activity actually removed from a generator during a single elution, expressed as a percentage of the activity expected at that time.

Contamination of eluted technetium-99m with parent molybdenum-99, measured as a ratio of activities and limited by regulation because the parent adds unnecessary dose.

The fraction of total activity in a preparation that comes from the intended radionuclide, with the remainder being contaminating radionuclides.

The fraction of activity present in the desired chemical form, such as pertechnetate versus hydrolyzed or bound impurities, determined by chromatography or similar testing.

Unbound technetium-99m that was not incorporated into the intended radiopharmaceutical, appearing as an impurity that can mimic uptake in thyroid, stomach, or salivary tissue.

The combined half-life from physical decay and biological clearance, computed as the product of the physical and biological half-lives divided by their sum.

The average time that activity remains in a source organ, calculated by integrating the time-activity curve and dividing by the administered activity.

A plot of measured or modeled activity in a region versus time, used to derive uptake and clearance kinetics for dosimetry.

A formalism for internal dose estimation in which the dose to a target region equals the sum over source regions of the residence time times a precomputed S value.

A tabulated quantity giving absorbed dose to a target region per unit of cumulated activity in a source region, incorporating decay emissions and anatomy.

Energy deposited per unit mass in tissue, expressed in gray, where one gray equals one joule per kilogram.

Absorbed dose averaged over a tissue and weighted by radiation type to account for differing biological effectiveness, expressed in sievert.

A whole-body risk-weighted quantity summing tissue equivalent doses with tissue weighting factors, used to compare stochastic risk across procedures.

The principle of keeping radiation doses as low as reasonably achievable, considering economic and social factors, through time, distance, and shielding.

A prospective restriction on individual dose used in planning, set below the dose limit, to encourage optimization rather than to define compliance.

A regulatory maximum permissible dose for occupational or public exposure that must not be exceeded, distinct from optimization targets.

An imaging device using a collimator, scintillation crystal, photomultiplier tubes, and position logic to map the distribution of a radiotracer.

A lead structure with holes that restricts the direction of incident photons reaching the detector, trading sensitivity for spatial resolution.

A selected range of pulse heights accepted by the imaging system to include photopeak events while rejecting scattered photons.

The minimum separation at which two point sources can be distinguished, often reported as full width at half maximum of a line spread function.

Underestimation of activity concentration in objects smaller than the system resolution because counts from the object spread into surrounding regions.

The ratio of measured to true activity concentration for a region, used to correct small-object quantification losses in emission tomography.

Compensation for photon loss within the patient, typically using transmission or computed tomography data, to make activity estimates quantitative.

Removal or reduction of detected events that have lost energy by Compton interaction, improving contrast and quantitative accuracy.

A normalized measure of tracer concentration divided by injected activity and body size, used to compare uptake across patients and studies.

A positron-emitting compound whose annihilation photons are detected in coincidence, enabling high-sensitivity imaging of metabolic or receptor processes.

Identification of two nearly simultaneous annihilation photons arriving on opposite sides of the detector ring, defining an event line through the patient.

An accidental pairing of photons from two separate decays detected within the timing window, adding background that increases with activity and timing window width.

Use of small arrival-time differences between annihilation photons to localize the event along the line of response, improving signal-to-noise in PET.

A radiolabeled agent delivering tumoricidal absorbed dose, such as iodine-131 or lutetium-177 compounds, governed by patient-specific dosimetry and release criteria.

Regulatory conditions allowing discharge of a treated patient when the dose to others is projected to stay below specified limits, based on activity and exposure rate.

A patient's voluntary agreement to a procedure after receiving understandable information about purpose, risks, benefits, and alternatives.

A collaborative process in which clinician and patient exchange information and jointly choose a course of care consistent with patient values.

Principles governing human-subject research, including respect for persons, beneficence, and justice, enforced through review boards and consent processes.

An independent committee that reviews and monitors research involving human subjects to protect participants' rights and welfare.

A situation in which financial or personal interests could improperly influence professional judgment, requiring disclosure and management.

Evaluation of professional work or performance by qualified colleagues against accepted standards, used for quality assurance and credentialing.

An organized set of policies, tests, and reviews ensuring equipment, procedures, and personnel consistently meet required performance and safety standards.

An administration of byproduct material that differs substantially from the prescribed dose or involves the wrong patient, radiopharmaceutical, or route, requiring reporting.

The conduct expected of a medical physicist, including competence, honesty, accountability, respect for patients and colleagues, and service above self-interest.

The range of duties and responsibilities a professional is trained and authorized to perform, often defined by law, regulation, or institutional policy.

Reporting unsafe or unlawful practices to appropriate authorities after internal channels fail, protected when done in good faith for patient safety.