Dental Radiography for DCPs Revision Flashcards

Comprehensive vocabulary flashcards covering dental radiography principles, equipment, safety regulations (IRR/IRMER), techniques, and pathological interpretation for DCP revision.

Photons

A type of electromagnetic radiation that comes in a wide range of energies which determine their properties.

Ionising Radiation

High-energy electromagnetic radiation, specifically Gamma rays and X-rays, capable of interacting with and displacing electrons from atoms.

X-rays vs. Gamma rays

Technically the same entities; however, Gamma rays are naturally occurring while X-rays are man-made.

Transmission

An interaction where X-ray photons pass straight through matter without touching anything.

Pure Scatter

An interaction where X-ray photons are deflected in another direction with no loss of energy.

Deterministic Effects (Tissue Reaction Effects)

Certainty effects resulting from high doses of radiation where damage severity is proportional to the dose; dental radiography does not use doses high enough to cause these.

Stochastic Effects

Chance effects that can result from any dose of radiation; the severity of damage bears no relation to the dose, but the probability increases as dose increases.

Somatic Cells

Normal body cells; damage to these may result in chance effects like fatal cancer.

Genetic Effects

Chance effects occurring in reproductive cells (egg and sperm) that may appear in future offspring.

Cathode

The part of the X-ray tube containing a tungsten wire filament where electrons are generated.

Anode

A tungsten target set into a block of copper where high-speed electrons collide to produce X-rays.

Step-up Transformer

An electrical device that converts ordinary mains voltage ($240\,V$) to the high voltage required for X-ray production ($70,000\,V$ or $70\,kV$).

kV (Kilovoltage)

Controls the energy and penetrating power (quality) of the X-ray beam; increasing this decreases contrast ('kV kills contrast').

mA (Milliamperage)

Along with 'Time', this variable controls the quantity of X-ray photons produced and the degree of film blackening.

Aluminium Filter

A component used to remove harmful, lowest-energy X-ray photons from the beam; recommended thickness is $1.5\,mm$ for $<70\,kV$ sets and $2.5\,mm$ for $>70\,kV$ sets.

Collimation

The restriction of the size and shape of the X-ray beam; rectangular is recommended, or a maximum diameter of $60\,mm$ for circular types.

Photo-electric Effect

Interaction where an X-ray photon hits an inner-shell electron; the chance follows the atom's Atomic Number cubed ($Z^3$).

Compton Effect

Interaction where an X-ray photon hits an outer-shell electron, losing only some energy before being deflected.

Ionisation

The process of creating an unstable atom (positive ion) and a stray electron (negative ion) through collisions with radiation.

Indirect Damage

Damage caused when X-ray photons ionise water molecules, producing toxic substances like hydrogen peroxide and hydrogen gas.

Gray (Gy)

The unit used to measure Radiation Absorbed Dose, which is the total amount of radiation absorbed by the patient.

Sievert (Sv)

The unit for both Equivalent Dose and Effective Dose; accounts for radiation damage potential or tissue sensitivity.

Radiation Weighting Factor ($W_R$)

A factor used to calculate Equivalent Dose based on radiation type damage; for X-rays, the value is $1$.

Tissue Weighting Factor ($W_T$)

A factor used to calculate Effective Dose based on tissue sensitivity; gonad, red bone marrow, and lung tissue are most sensitive.

Annual Dose Limit (Non-classified Workers)

The legal yearly limit for staff working with radiation is $20\,mSv$ per year, though the recommended constraint is $0.3\,mSv$.

Solid-state Receptors

Real-time or 'corded' digital systems that produce instantaneous images by converting X-ray energy into electrical signals.

Phosphor Plate Receptors

Storage plate or 'cordless' systems that store the image on a plate to be later scanned by a laser reader.

Voxels

Tiny cubes of digital information that make up 3D images in Cone Beam Computed Tomography (CBCT).

Intensifying Screens

Fluorescent phosphors (like calcium tungstate or rare earth materials) in a cassette that emit light to expose indirect-action film.

Latent Image

The invisible image formed on a film or sensor after exposure but before processing.

Development

The chemical process where sensitised areas of green emulsion are reduced to black metallic silver; sensitive to time and temperature.

Fixation

The chemical process that removes all un-sensitised emulsion to reveal the clear base; inadequate fixer causes greenish-yellow or brown staining.

ALARP Principle

A key concept of Optimisation in radiation protection: 'As Low As Reasonably Practicable'.

Controlled Area

A designated zone where specific radiation protection rules apply; operators should stand at least $1.5\,m$ away from equipment if not outside this area.

Radiolucent

Black areas on a radiograph where X-ray photons passed through without absorption.

Radiopaque

White areas on a radiograph where X-ray photons were totally absorbed by the patient.

Tomograph

An image of a 'slice' of the patient, such as a Dental Panoramic Tomograph (DPT).

Periapical Radiography

Designed to show individual teeth and the tissues around the apices; taken via paralleling or bisected angle techniques.

Focal Trough

The 3D horseshoe-shaped 'in-focus' layer in panoramic radiography; structures within it appear sharp and slightly magnified.

Bitewing

A radiograph designed to image the crowns of premolar and molar teeth to detect caries or assess periodontal status.

SLOB Rule

An acronym for horizontal parallax: 'Same Lingual, Opposite Buccal'; helps locate unerupted teeth.

Quality Assurance (QA)

An organised effort to ensure diagnostic images are of high quality while keeping costs and radiation doses at ALARP levels.

IRR 2017

Ionising Radiations Regulations; legislation primarily concerned with the safety of workers and the general public.

IRMER 2017

Ionising Radiation (Medical Exposures) Regulations; legislation concerned with the safety of patients and the justification of exposures.

Lamina Dura

The white line seen radiographically representing the tooth socket; its disappearance can indicate periapical disease.

Primary Squamous Cell Carcinoma

The most common oral cancer, appearing on radiographs as irregular destruction of bone.

Odontome

A developmental defect appearing as either multiple small teeth (Compound) or a radiopaque jumble of dental tissues (Complex).