Amaya's Radio exam 1 (chap. 1-8 & 18-19)

Who invented/discovered the x ray

Roentegen

Radiation

A form of energy carried by waves or a stream of particles

Fluorescence

a glow that results when a fluorescent substance is struck by light, cathode rays, or x-rays

Radiograph

an image or picture produced on a receptor (radiation-sensitive film, phosphor plate, or digital sensor) by exposure to ionizing radiation; a two-dimensional representation of a three-dimensional object

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 an image receptor to x-rays

Radiology

The science or study of radiation as used in medicine; a branch of medical science that deals with the therapeutic use of x-rays, radioactive substances, and other forms of radiant energy

X radiation

a high-energy radiation produced by the collision of a beam of electrons with a metal target in an x-ray tube

X ray

A beam of energy that has the power to penetrate substances and record image shadows on photographic recepotors

Who exposed the first dental radiograph

Walkhoff

Who exposed the first dental radiograph in the U.S. (living patient)?

Kells

What charge does a proton have

positive

What charge does a neutron have

neutral (no charge)

What charge does an electron have

negative

Radioactivity

the process by which certain unable atoms or elements undergo spontaneous disintegration/ decay in effort to attain a more balanced nuclear sate

Ionizing radiation

Radiation capable of producing ions by removing or adding an electron to an atom

Labeling of the X ray tubehead

What parts of the x ray tube head contain lead?

Lead collimator

Metal housing

Tube head seal

Position indicating device

Leaded glass housing

What are the periods for radiation exposure?

Latent period

Period of injury

Recovery period

Cumulative effects

Latent period

the time that elapses between exposure to ionizing radiation and the appearance of observable clinical signs

Period of injury

After latent period, cellular injuries occurs such as

cell death

changes cell in function

breaking or clumping of chromosomes

formation of giant cells

cessation of mitotic activity

Abnormal mitotic activity

Recovery period

Last event in sequence

Cell damage followed by repair

Cumulative effects

Repeated radiation exposure can lead to health problems

Radiosensitive Tissues / Organs

small lymphocyte

bone marrow

reproductive cells

intestinal mucosa

skin

lens of eye

oral mucosa

Radioresistant tissues/organs

Muscle tissue

nerve tissue

mature bone

cartilage

salivary gland

thyroid gland

kidney

liver

Somatic radiation effects

Injury in somatic cells that produce poor health and iridate the individual

Genetic radiation effects

Effects not seen in the irradiated person but are passed to future generations

Collimation

Restricts size and shape of x ray beam and reduce patient exposure

Soamtic cells

Cells in the body except reproductive

Genetic cells

The reproductive cells (Ova and sperm)

Inherent filtration

When primary beam passes through X ray Tube ,insulating, oil, and tube head seal with .5 to 1.0 mm of filtration

Added filtration

Aluminum disks in path of X ray beam, between collimator and x ray seal to filter out longer wavelengths and low energy x rays

Total filtration

Inherent + added

Machines at or below 70 kV need a minimum of 1.5 mm of aluminum filtration Above 70 kV you need 2.5 or above

What beam is wanted for an x ray?

A high-energy, penetrating, and hardened x-ray beam

What does maximal permissible dose mean?

Maximum does the body can endure with little or no injury

What is the maximal permissible dose?

50 mSv / year

.05 Sv/ year

5.0 rem/year

ALARA Concept

As low as reasonably achievable

Ways to protect the patient

Proper prescribing of dental images

Proper equipment (aluminum filter, collimator, PID)

Thyroid collar

Lead apron

Digital sensors/fast film

Beam alignment devices

Exposure factor selection

Proper technique when taking images

Proper film processing and receptor handling

X ray beam quality definition

Describe the mean energy or penetrating ability of the x ray beam

What is the quality of a beam controlled by?

Kilovoltage because it regulates the speed/energy of electrons and determines penetrating ability

What is x ray beam density?

Overall darkness/blackness of an image

What happens to density when kilovoltage is increased?

Image has more density and is darker

What happens to density when kilovoltage is decreased?

Images has less density and is lighter

What is contrast?

how sharply dark and light areas are differentiated or separated on image

What happens to contrast when kilovoltage is decreased?

High contrast

Many black and white areas with few shades of gray

Used for carries

What happens to contrast when kilovoltage is increased?

Low contrast

Many shades of gray

Use for periapical disease

What is exposure time?

Interval of time during which x rays are produced

What is the relationship between exposure time and kilovoltage?

Inverse

more exposure = more x rays = darker image

What is quantity of a beam controlled by?

Milliamperage

What is x ray beam quantity?

Number of x rays produced in the dental x ray unit

What happens to density when milliamperage is increased?

Higher density and a darker image

What happens to density when milliamperage is decreased?

Lower density and a lighter image

What happens to exposure time when milliamperage is increased?

Exposure time was decreased

What happens to exposure time when milliamperage is decreased?

Exposure time was increased

What is x ray beam intensity?

Both quality and quantity as a product

X ray beam intensity and Kilovoltage relationship

Higher kV = Higher intensity because more energy and shorter wavelengths

X ray beam intensity and Milliamperage relationship

Higher mA = higher intensity because of more electrons/ x rays produced

X ray beam intensity nd exposure time

Higher exposure time = more intense

Target surface distance

The distance from the source of radiation (tungsten target in anode) to the patients skin

Target object distance

The distance from the source of radiation to the tooth

Target receptor distance

The distance from the source of radiation to the receptor

Inverse square law

the intensity of radiation is inversely proportional to the square of the distance from the source of radiation

Half value layer (HVL)

the thickness of aluminum , when placed in the path of the x-ray beam, reduces the exposure rate by one-half.

Parts of X ray machine?

control panel, extension arm, tube head

What is kilovoltage used for?

The peak voltage of an alternating current

What is milliamperage used for?

Regulates the temperature of the cathode filament

Radiolucent

Portion of an image that is dark or black

Radiopaque

Portion of image that appears light or white

What is a step wedge used for ?

To check contrast

Sharpness

aka detail, definition or resolution

Capability of receptor to reproduce the distinct outlines of an object

What factors influence sharpness?

Focal spot size, film composition, movement

Penumbra

Unsharpness, blurry, fuzzy, unclear area

Magnification

Radiographic image that appears larger than actual size of the object it represents

What factors influence magnification?

Target-receptor distance

Object-receptor distance

Distortion

variation in the true size and shape of the object being radiographed

What factors influence distortion?

object-receptor alignment

x-ray beam angulation

Intraoral X ray machine parts

tube head, extension arm, control panel

Extra oral x ray machine parts

Position indicating devices

Panoramic

Cephalometric

Skull imaging

Cone beam computer tomography

What are the types of dental receptor holders

Bite block

Endoray

Snap a Ray

XCP

What devices are used for digital imaging

X ray unit

Sensor

Computer

Direct digital imaging

Method of obtaining a digital image, in which an intraoral sensor is exposed to x-radiation to capture a radiographic image that can be viewed on a computer monitor

Indirect digital imaging

A sensor after exposure is scanned and converted toa digital form that can be viewed on a computer monitor

Advantages of digital imaging

-Superior gray-scale resolution

-Reduced exposure to x-radiation

-Increased speed of image viewing

-Lower equipment and film cost

-Increased efficiency

-Enhancement of diagnostic image

-Effective patient education tool

Periapical examination purpose

used to examine the entire tooth (crown and root) and supporting bone

Interproximal examination purpose

To examine the crowns of both the maxillary and mandibular teeth on a single image

occlusal examination purpose

Used to examine large areas of the maxilla or mandible on one image

Parallel technique

1) Long axis of tooth and the receptor are parallel to each other

2) The central ray is directed perpendicular to the long axis of the tooth and film

3) The beam alignment device must be used to keep the receptor parallel to the tooth

Relationship between a focal spot and x ray image

smaller focal spot = Sharper image

Relationship between PID length and target receptor distance

A longer PID has less magnification

Relationship between distortion and object receptor distance

More distortion the further you are from an image

Relationship between receptor image and distortion

If the receptor is not parallel with the object the more likely distortion will occur

What happens when vertical angulation is steep (+70 degrees)

Foreshortening

What happens when the vertical angulation is flat (+20 degrees)

Elongation