Dental Radiology

Basic's of radiology

Long wavelengths have LOW energy, & low frequency thus…

 Have poor penetrating ability

Extension Arm

Suspends the x-ray tubehead and allows for movement and positioning.

Tubehead

Tightly sealed, heavy metal housing containing the x-ray tube that produces dental x-rays.

Aluminum Filtration

Filters out nonpenetrating, longer wavelength x-rays.

Lead Collimator

Restricts the size of the x-ray beam.

Position-Indicating Device (PID)

Aims and shapes the x-ray beam.

Leaded Glass Housing

Prevents x-rays from escaping in all directions.

Cathode

The negative electrode that supplies the electrons necessary to generate x-rays.

Tungsten Filament

Supplies the electrons to generate x-rays.

Made of copper to withstand heat

Boils off electrons

Anode

The positive electrode that converts electrons into x-ray photons.

Focal Spot

The exact area where electrons strike the target, important for image sharpness.

Line Focus Principle (Bensons principle)

Places the target at an angle (15-20 degrees) to distribute heat and create a smaller effective focal spot.

Filament Circuit

Controls the flow of current to the filament.

Controlled by the mA setting in the control panel

High-Voltage Circuit

Accelerates electrons from cathode to anode to generate x-rays.

Transformers

device that is used to either increase or decrease the voltage in an electrical circuit.

Periapical X-ray

Shows the entire tooth and surrounding structures.

Bitewing X-ray

Shows the crowns of the upper and lower teeth in occlusion.

Occlusal X-ray

Shows the entire arch of teeth in either the upper or lower jaw.

Paralleling Technique

Sensor and tooth are parallel for image accuracy.

Bisecting Technique

Sensor is placed at an angle to the tooth for image accuracy.

Radiopaque

Substance that appears white or light gray on a radiograph.

Electromagnetic Spectrum

Range of all possible frequencies of electromagnetic radiation.

Parts of an Atom

Protons, neutrons, and electrons.

Four Conditions for X-ray Generation

Generation of electrons

Focusing of those electrons

Production of high-speed electrons

Stopping of high-speed electrons with target

Short wavelengths have HIGH energy, & high frequency thus…

Have high penetrating ability

High-voltage circuit

Controlled by the kVp setting in the control panel

Step-down transformer

Used to decrease the voltage

Step-up transformer

 Used to increase the voltage

Thermionic emission

The release of electrons from the tungsten filament when the electrical current passes through it and heats the filament

Binding energy

• determined by the distance between the nucleus and the orbiting electron

• The strongest binding energy is found closest to the nucleus in the K shell

Particulate radiation

consists of tiny, fast-moving particles that have energy and mass.

Travel in straight lines and at high speeds.

 Ionization

The process in which the atom gains or loses an electron

Filament circuit uses ____

3 to 5 volts

controlled by mA

High Voltage circiut uses ____

65,000 to 10,000 volts

controlled by kVp

What is dental radiology scatter?

radiation that spreads out in different directions from a radiation beam.