Radiation Safety and Production of X-Rays

Week 2

Weightless bundles of energy (photons) without an electrical charge that travel in waves at the speed of light

X-ray beams

When X-ray beams strike a patient's tissue. This is the harmful effect of X-ray beams in humans that results in the disruption of cellular structure and causes permanent damage to living cells and tissue

Ionization

A minute bundle of pure energy that has no mass or weight

Photon

During ionization, electrons are removed from electrically stable atoms by collisions with

Photons

Made of photons that travel through space at the speed of light in a straight line, with a wavelike motion / X-ray beams (together with visible light, radar, radio, and television waves) belong to a group called

Electromagnetic radiation

The stream of radiation is emitted from the X-ray unit. Travels in a straight line and contains powerful short wavelengths. Produce diagnostically useful radiographs

Primary radiation (or central ray or primary beam)

Given off after the primary beam comes into contact with the soft tissue of the head, the bones of the skull, and the teeth. It is less penetrating than primary radiation because the rays become weaker after they contact the tissue; however, the patient still may absorb these rays

Secondary radiation

A form of secondary radiation that occurs when an X-ray beam is deflected from its path during impact with the patient. Travels in all directions and is impossible to confine; and without adequate protective barriers, the operator and others nearby may be affected by exposure to this kind of radiation.

Scatter radiation

Radiation that escapes in all directions from a faulty X-ray tube head

Leakage radiation

Amount of radiation to which a person is exposed

Radiation exposure

The amount of radiation energy actually absorbed by tissue is

Absorbed dose

Used to compare the biological effects of different types of radiation

Dose equivalence

Radiation we are exposed to every day. Comes from natural sources

Background radiation

The exposure limit for those who are occupationally exposed to radiation when observing all safety practices

Maximum permissible dose (MPD)

Concept that states that all exposure to radiation must be kept As Low As Reasonably Achievable

ALARA principle

The effects of radiation may not become evident for many years after the time when the X-ray beams were absorbed. This time lag is called

Latent period

Exposure to radiation builds over time, it has a

Cumulative effect

Occurs when a large dose of radiation is absorbed in a short time, such as in a nuclear accident

Acute radiation exposure

Occurs when small amounts of radiation are repeatedly absorbed over a long period. It may take years before effects are observed

Chronic radiation exposure

Genetic cells are the reproductive cells (sperm and ova). Damage to genetic cells is passed on to succeeding generations. These genetic changes are referred to as

Genetic mutations

When using the conventional film-based technique _____ is the single most effective method of reducing a patients exposure to x-ray beams

Fast-speed film

What is the fastest intraoral film available?

F-speed film or InSight

Requires significantly less X-radiation than conventional film-based radiography because the sensor used to capture the image is more sensitive to X-ray beams than conventional film

Digital imaging

____ of the x-ray beam results in higher energy and a more penetrating, useful beam

Filtration

Used to restrict the size and shape of the X-ray beam and to reduce patient exposure

Collimation

A lead plate with a hole in the center. Placed directly over the opening in the machine housing where the X-ray beam exits the tubehead

Collimator

Used to aim the X-ray beam at the film in the patient's mouth, thereby minimizing the amount of radiation to the patient's face

Position indicator device (PID)

It can be worn by the operator or placed on x-ray equipment or on walls. Protects the operator by identifying occupational exposure to radiation

Radiation monitors

The primary function is to house the dental X-ray tube. Made of metal and has a protective lead lining to prevent any radiation from escaping

Tubehead

Part of the cathode and keeps the electrons suspended in a cloud at the cathode. When the exposure button is pressed, the circuit within the tubehead is completed, and the electrons very rapidly cross from the cathode (-) to strike the anode (+)

Focusing cup

Acts as the target for the electrons. Consists of a tungsten target (a small block of tungsten) that is embedded in the larger copper stem

Anode

Similar to the filter. A metal disc, usually lead, that has a small opening in the center to control the size and shape of the X-ray beam as it leaves the tube head

The Collimator

Also known as the target-film distance. The distance between the source of the X-ray beams (focal spot on the tungsten target) and the film. The length of the PID determines the _____. A longer PID reduces distortion as a result of magnification

Source-film distance

An aluminum disc is located at the port of the tubehead where the POD is connected. Removes low-energy, long-wavelength x-ray beams

Filter

Hollow and encloses the wire between the tubehead and the control panel. Plays an important role in positioning the tubehead

Extension arm

Contains the master switch and two indicator lights, an exposure timer, an mA selector, and the kV selector

Control panel

Structures appear dark or black on the radiograph. Air spaces, soft tissues of the body, and dental pulp appear as

Radiolucent

Structures appear white or light gray on the radiograph. Metal, enamel, and dense areas of bone appear as

Radiopaque

The differences between the shades of gray in a radiograph are called

Contrast (controlled by the kilovolt peak kVp setting)

Overall blackness or darkness of a radiograph

Density (controlled by the mA setting controls)

Describes the distance between the teeth (object) being radiographed and the radiographic film

Object-film distance (OFD) (placing the film close to the teeth reduces distortion or the lack of sharpness)