Dental Radiography: Introduction, History, and Radiation Physics

Vocabulary flashcards covering key definitions, historical pioneers, dental radiography techniques, equipment components, and radiation physics mechanisms.

Heinrich Geissler

Built the first vacuum tube in 1838, which was later used in the work of making neon lighting.

Johann Hittorf

Used the vacuum tube to study fluorescence in 1870 and became the first scientist to calculate the electric capacity of ions.

William Crookes

Discovered in the late 1870s that cathode rays were streams of charged particles.

Philip Lenard

Discovered in 1894 that cathode rays could penetrate a thin window of aluminum foil.

Wilhelm Conrad Roentgen

Bavarian physicist known as the "Father of X-rays" who discovered X-rays on Nov. 8, 1895.

Otto Walkhoff

Made the 1st dental radiograph in 1895 by exposing his own mouth on a photographic plate for 25 minutes.

W.J. Morton

Made the 1st radiograph using a skull in 1895 and gave early warnings regarding the adverse effects of X-rays.

C. Edmund Kells

Exposed the 1st dental radiograph in the United States using a living person in 1896 and introduced the paralleling technique.

William Coolidge

Invented the hot cathode X-ray tube in 1913.

Weston Price

Introduced the bisecting technique in 1904.

Howard Riley Raper

Refined the original bisecting technique and introduced the bite-wing technique in 1925.

Hisatugu Numata

First person to expose a panoramic radiograph in 1933 using the concept of rotation.

F.G. Fitzgerald

Introduced the long-cone paralleling technique in 1947.

Cone-Beam Computed Tomography (CBCT)

A 3D imaging technique introduced in 1999 that allows imaging without distortion.

Radiation

Energy carried by waves or streams of particles, or the production and spread of energy through space or a substance in the form of waves or particles.

X-radiation

High-energy, ionizing electromagnetic radiation produced by the collision of a beam of electrons with a metal target in an X-ray tube.

X-ray

A weightless bundle of energy (photon) without an electrical charge that has the power to penetrate substances and record image shadows on a receptor.

Radiology

The science or study of radiation as used in medicine, dealing with X-rays, radioactive substances, and radiant energy in diagnosis and treatment.

Radiograph

A picture or visible photographic record on a receptor produced by the passage of X-rays through an object or body.

Dental radiograph

A photographic image produced on a receptor by the passage of X-rays through teeth and related structures.

Radiography

The art and science of making radiographs by the exposure of a receptor to X-rays.

Dental radiography

The production of radiographs of the teeth and adjacent structures by the exposure of a receptor to X-rays.

Dental radiographer

Any person who positions, exposes, and processes X-ray film or receptors.

Image receptor

A recording medium used in radiography, such as X-ray film, phosphor plate, or digital sensor.

Dental imaging

The creation of digital, print, or film representations of anatomic structures for the purpose of diagnosis.

Matter

Anything that occupies space and has mass.

Atom

The fundamental unit of matter composed of a central nucleus (protons and neutrons) and orbiting electrons.

Binding energy

The electrostatic force between the positive nucleus and orbiting electrons that maintains electrons in their orbits, measured in electron volts ($\text{eV}$) or kilo electron volts ($\text{keV}$).

Ion

An atom that gains or loses electrons and becomes electrically unbalanced.

Ionization

The process of converting an atom into ions, producing a positive ion and an ejected negative electron (ion pair).

Radioactivity

The process where unstable atoms undergo spontaneous disintegration or decay to attain a more balanced nuclear state.

Particulate radiation

Tiny particles of matter possessing mass that travel in straight lines at high speeds.

Alpha particles

Particulate radiation emitted from the nuclei of heavy metals consisting of two protons and two neutrons without electrons.

Beta particles

Fast-moving electrons emitted from the nucleus of radioactive atoms.

Cathode rays

Fast-moving electrons that originate in an X-ray tube.

Electromagnetic radiation

The spread of wavelike energy without mass through space or matter in electric and magnetic fields positioned at right angles ($90^\circ$) to one another.

Photon

A bundle or quantum of electromagnetic energy with no mass or weight that travels as a wave through space at the speed of light.

Wavelength

The distance between the crest of one wave and the crest of the next, measured in nanometers for short waves and meters for long waves.

Frequency

The number of wavelengths that pass a given point in a specified length of time.

Control panel

The wall-mounted component of an X-ray machine containing the power switch, indicator light, and control devices for exposure time, kilovoltage, and milliamperage.

Extension arm

The component of the X-ray machine that suspends the tubehead, houses electrical wires, and allows horizontal and vertical positioning.

Tubehead

A tightly sealed, heavy metal housing containing the X-ray tube, transformers, and insulating oil.

Insulating oil

Oil in the tubehead that surrounds the X-ray tube and transformers to absorb heat and prevent overheating.

Aluminum disks

Disks in the tubehead seal that filter out nonpenetrating, longer wavelength X-rays.

Lead collimator

A lead diaphragm that restricts the size and shape of the X-ray beam.

Position-indicating device (PID)

An open-ended cylinder or rectangular device attached to the tubehead that aims and shapes the X-ray beam.

Cathode

The negative electrode in an X-ray tube consisting of a tungsten filament and molybdenum cup to supply electrons.

Anode

The positive electrode in an X-ray tube consisting of a tungsten target and copper stem that converts electrons into X-ray photons.

Thermionic emission

The release of electrons from the tungsten filament when heated by an electrical current.

Direct current (DC)

Electrical current in which electrons flow in only one direction through a conductor.

Alternating current (AC)

Electrical current in which electrons flow in two opposite directions.

Rectification

The conversion of alternating current ($\text{AC}$) to direct current ($\text{DC}$), performed self-containedly by the dental X-ray tube.

Amperage

The measurement of the number of electrons moving through a conductor, measured in amperes ($\text{A}$) or milliamperes ($\text{mA}$).

Voltage

The measurement of electrical force causing electrons to move from a negative pole to a positive pole, measured in volts ($\text{V}$) or kilovolts ($\text{kV}$).

Filament circuit

The low-voltage circuit using $3-5\,\text{V}$ that regulates electrical current flow to the cathode filament, controlled by $\text{mA}$ settings.

High-voltage circuit

The circuit using $65,000-100,000\,\text{V}$ that provides the high voltage required to accelerate electrons to the anode, controlled by $\text{kV}$ settings.

Step-down transformer

A transformer used to decrease incoming line voltage ($110\,\text{V}$ or $220\,\text{V}$) to $3-5\,\text{V}$ for the filament circuit.

Step-up transformer

A transformer used to increase incoming voltage to $65,000-100,000\,\text{V}$ for the high-voltage circuit.

Autotransformer

A voltage compensator in the X-ray circuit that corrects for minor fluctuations in current.

General radiation

Braking radiation (bremsstrahlung) produced when high-speed electrons slow down or stop near tungsten nuclei, accounting for approximately $70\%$ of X-rays produced.

Characteristic radiation

Radiation produced when a high-speed electron dislodges an inner-shell electron of a tungsten atom at $\ge 70\,\text{kVp}$, triggering electron rearrangement.

Primary radiation

The penetrating X-ray beam produced at the target that exits the tubehead, also called the primary or useful beam.

Secondary radiation

Radiation created when the primary beam interacts with matter such as tissues, bones, and teeth.

Scatter radiation

A form of secondary radiation where an X-ray photon is deflected from its path by interaction with matter.

Photoelectric effect

Ionization interaction where an X-ray photon gives up all its energy to eject an inner-shell electron, accounting for $30\%$ of interactions with matter.

Compton scatter

Ionization interaction where an X-ray photon collides with an outer-shell electron, ejecting a recoil electron and scattering at a lower energy level; accounts for $62\%$ of interactions with matter.

Coherent scatter

Unmodified scatter interaction where a low-energy photon changes path upon interacting with an outer-shell electron without energy change or ionization; accounts for $8\%$ of interactions with matter.