ABR TMP key terms

The ratio, expressed as a percentage, of absorbed dose at a given depth along the central axis to the maximum dose at the same field size and source-to-surface distance.

The ratio of absorbed dose at a given depth in a phantom to the dose at a reference depth, with the source-to-detector distance held constant; used for isocentric calculations.

The physical principle that photon fluence and dose decrease with the square of the distance from a point source, used to correct dose when distance changes.

The process of converting a prescribed dose at a point into the linear accelerator monitor units needed, accounting for output, depth, field size, distance, and modifiers.

A cumulative or differential plot showing how much volume of a structure receives at least a given dose, used to evaluate target coverage and organ sparing.

A numerical measure comparing the treated volume receiving a specified dose with the target volume, often expressed as a ratio of intersection to target or prescription volume.

A metric describing how uniformly dose is distributed within a target volume, often calculated from maximum, minimum, mean, or prescription dose values.

The uniform dose that would produce the same biological effect on a tumor or normal tissue as the actual nonuniform dose distribution.

A dose calculation method that models photon energy deposition by convolving or superposing dose kernels with the incident fluence, accounting for tissue heterogeneities better than simple correction methods.

The ratio of dose with a wedge to dose without it at the same point, used to correct monitor unit calculations when a wedge modifies the beam.

A dose comparison tool that combines dose difference and distance-to-agreement into a single pass-fail metric, commonly used for patient-specific quality assurance.

The AAPM protocol for clinical reference dosimetry of high-energy photon and electron beams, specifying calibration conditions, ionization chamber use, and correction factors.

The AAPM task group report providing quality assurance recommendations and tolerances for medical linear accelerators, including daily, monthly, and annual tests.

The stability of radiation output per monitor unit over time, checked with a chamber or detector to ensure the accelerator delivers the intended dose.

Beam profile metrics describing how uniform dose is across the central portion of a radiation field and how closely the left/right and top/bottom sides match.

A geometric test using a small target and portal images at multiple gantry, collimator, and couch angles to verify that the radiation isocenter coincides with the mechanical isocenter.

An MLC quality assurance test that images a series of narrow slit fields at different leaf positions to evaluate leaf position accuracy and reproducibility.

The ability of multileaf collimator leaves to accurately reach and hold commanded positions, which is critical for conformal and intensity-modulated dose delivery.

A comprehensive workflow test that follows a phantom through imaging, planning, delivery, and analysis to confirm the entire treatment process agrees with expectations.

Measurement of dose on or in a patient during treatment using detectors such as diodes or thermoluminescent dosimeters, used to verify delivered dose.

The AAPM protocol for brachytherapy source dosimetry that defines dose calculation in water using air kerma strength, dose rate constant, radial dose function, and anisotropy function.

A brachytherapy source specification equal to air kerma rate multiplied by the square of the distance, expressed in units such as microgray-meter squared per hour.

The dose rate in water at one centimeter along the transverse axis per unit air kerma strength for a brachytherapy source, forming the reference normalization in TG-43.

A dimensionless TG-43 factor describing how dose falls off with distance along the transverse axis of a brachytherapy source, after removing inverse-square effects.

A TG-43 factor accounting for the angular dependence of dose around a brachytherapy source due to encapsulation and self-absorption, relative to the transverse axis.

The duration a high-dose-rate brachytherapy source remains at a programmed dwell position within the applicator, determining the dose contributed at that location.

A remote-controlled brachytherapy device that drives a high-activity source through catheters to programmed dwell positions inside the patient for temporary treatment.

A scaled value representing tissue attenuation relative to water and air on a CT scan, used to characterize tissues and support dose calculation.

A volumetric imaging technique using a flat-panel detector and a rotating kilovoltage source, commonly used for patient setup verification before treatment.

The process of aligning two imaging datasets, such as planning CT and daily CBCT, using rigid or deformable transformations to map anatomy.

A small implanted or external object visible on imaging, used to localize a target or verify alignment between planning and treatment images.

The radiation protection principle of keeping exposures to workers, patients, and the public as low as reasonably achievable, considering economic, social, and technical factors.

The three practical methods for reducing radiation exposure between a person and a source: limiting time near sources, increasing distance, and adding appropriate shielding.

Regulatory annual limits on radiation dose to workers, such as total effective dose and lens or extremity limits, designed to prevent deterministic effects and limit stochastic risk.

A proactive risk assessment method that identifies ways a process can fail, estimates severity, occurrence, and detectability, and prioritizes improvements.

An AAPM task group report that applies failure mode and effects analysis and fault tree analysis to radiation therapy quality management, emphasizing risk-based process improvement.

A standard for storing, transferring, and displaying medical images and related information, enabling interoperability among imaging, planning, and record-and-verify systems.

The radiation therapy extension of the DICOM standard, defining objects for structures, plans, doses, and treatment records so different systems can exchange planning and delivery data.

A messaging standard for exchanging clinical and administrative health information between hospital systems, used alongside imaging standards such as DICOM for workflow integration.

A retrospective structured method for identifying underlying system causes of an incident rather than blaming individuals, used to prevent recurrence.