PCN NDT Radiographic Testing Level 2 Exam key terms

The principle that radiation intensity from a point source decreases with the square of the distance, so doubling the distance reduces intensity to one quarter of its original value.

A measure of how strongly a material reduces radiation intensity per unit path length; it depends on photon energy and the material's density and atomic number.

The variation in radiation intensity transmitted through different regions of a specimen, determined by differences in thickness, density, and atomic number along the radiation path.

The amount of ionizing radiation energy deposited per unit mass of material, measured in grays; it provides the physical basis for assessing radiation effects on tissue.

A radiation protection quantity equal to absorbed dose multiplied by radiation weighting factors, expressed in sieverts, used to compare the biological risk of different radiation types.

The principle of keeping radiation exposure as low as reasonably achievable, considering economic and social factors, by controlling time, distance, and shielding.

A device worn by a radiographer to measure cumulative radiation dose over a monitoring period, such as a film badge or thermoluminescent dosimeter, used for dose records.

An area where radiation exposure is possible and access is restricted and supervised for protection purposes, marked with warning signs and defined in the radiation safety plan.

The thickness of a specified material that reduces the intensity of a radiation beam to half its original value, used to describe beam quality and shielding.

The area on an X-ray tube anode where X-rays are produced; a smaller focal spot improves image sharpness but limits the tube current that can be used.

The potential difference applied across an X-ray tube, which controls the energy and penetrating power of the produced X-rays and strongly affects radiographic contrast.

A sealed radioactive isotope such as iridium-192 or cobalt-60 used to produce gamma radiation for industrial radiography, selected according to specimen thickness and material.

Material placed in an X-ray beam to absorb low-energy photons, hardening the beam, reducing unnecessary dose, and improving image quality by removing radiation that would only cause scatter.

Radioactive material permanently enclosed in a capsule designed to prevent leakage during normal use; used in gamma radiography and subject to leak testing and regulatory control.

A measure of the darkness of a processed radiograph, defined as the logarithm of the ratio of incident light intensity to transmitted light intensity through the film.

A graph plotting optical density against the logarithm of relative exposure for a film, showing its speed, contrast gradient, and latitude.

A layer of phosphor material in a cassette that converts ionizing radiation into light, increasing the film's effective sensitivity and reducing the exposure needed.

The invisible pattern of changed silver halide grains formed in film by exposure to radiation, which becomes a visible image only after chemical development.

The chemical solution that converts exposed silver halide grains in film into visible metallic silver, turning the latent image into a measurable optical density.

The chemical solution that removes unexposed and undeveloped silver halide from processed film and hardens the emulsion, making the radiographic image permanent.

A filtered lamp in a darkroom that emits light to which radiographic film is relatively insensitive, allowing film handling and processing without causing fog.

Blurring of the radiographic image caused by the finite size of the radiation source; it increases with larger focal spot and greater object-to-film distance.

The distance from the radiation source to the film or detector surface, controlling geometric unsharpness and the radiation intensity reaching the film through the inverse square law.

The enlargement of a feature's image caused by divergence of radiation between source and detector, calculated from source-to-detector and source-to-object distances.

A document specifying all radiographic parameters for a component, including source, kilovoltage, distance, exposure, film, screens, image quality indicator, and coverage, ensuring repeatable inspections.

A device with defined wires or holes placed on the specimen or source side to verify radiographic sensitivity, contrast, and overall image quality.

The ability of a radiograph to reveal small discontinuities, usually expressed as the smallest detectable image quality indicator wire or hole diameter as a percentage of specimen thickness.

A false indication on a radiograph caused by film handling, processing, screens, or equipment rather than by a genuine discontinuity in the specimen.

An interruption or irregularity in the normal structure of a material, such as a crack, porosity, or inclusion, which may or may not be a defect depending on acceptance criteria.

A discontinuity or imperfection that exceeds the applicable acceptance criteria and therefore makes the component nonconforming under the relevant standard or specification.

A signal or image feature on a radiograph that requires interpretation to determine whether it arises from a genuine discontinuity or from an artifact.

Gas-filled cavities in a weld or casting, appearing as dark rounded spots on a radiograph and evaluated by size, number, and distribution against acceptance criteria.

A weld discontinuity where the weld metal fails to fuse to the base metal or previous passes, often appearing as a dark line or band aligned with the weld preparation.

A specification or code that defines allowable discontinuity types, sizes, and distributions for a component, against which radiographic indications are evaluated and accepted or rejected.

A documented and controlled description of how a radiographic inspection is performed, including scope, references, personnel, equipment, technique, and acceptance criteria.

The ability to link inspection records, materials, and results to their origin and history through documented identification, ensuring accountability and verification of the inspection.

The comparison of an instrument's readings against a known reference standard to establish its accuracy, performed at defined intervals and documented to maintain confidence in measurements.

A formal record of a radiographic inspection containing component identification, technique, results, acceptance decision, and signatures, providing documented evidence and traceability.