DTHY 210 midterm

Intraoral films

receptors placed inside of the patients mouth: Periapicals, bitewings/interproximals, and occlusals

Size 0 film

smallest, BW or periapical for children

Size 1 film

longer than 0, usually used for anterior PA in adults (canine shots)

Size 2 film

standard BW or periapical

Size 3 film

longer, used only for BW

Size 4 film

occlusal films

Periapicals

examines entire portion of tooth including crown and root; Must show 2-3 mm past apex

Bitewing/ interproximal exams

looks at crowns of max/mandibular teeth for the detection of interproximal caries and alveolar bone level

occlusal film

larger film used to examine large sections of the man/maxillary teeth

fill mouth series

individual radiographs to examine all teeth and tooth bearing areas; Both BW and periapical films; uses 14-19 (18-most common)

Extraoral radiographic examination

film is placed outside the mouth the examine large areas of the skull or jaw

film mount

may be cardboard, plastic, or vinyl; used to support and arrange dental radiographs in anatomic order

Why use a film mount

quicker and easier to view; stored easily; decreases chance of misplacement of films; prevents damage to films

film mount methods

identification dot is located in one corner of each intraoral film packed; all dots must face same direction; P film, all dots placed toward the occlusal side; BW film location of the dot doesn’t matter

labial mounting

radiographs are viewed as if the radiographer is looking directly at the patient; dot is raised when viewing if you are outside the patient facing in

lingual mounting

film is viewed as if you are standing on the patient’s tongue looking outward; Dots are DOWN

tips for mounding radiographs

maxillary molars have 3 roots; presence of sinus indicates the maxilla; mandibular molars have 2 roots

Radiation

Energy carried by waves or streams of particles

X-Radiation

High-energy radiation produced by the collision of a beam of electrons witha 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 film

Radiology

Science or study of radiation used in medicine

Radiograph

A photograph on film produced by a passage of x-rays through an object or body

Dental Radiograph

image produced on film by the passage of rays through teeth and related structures

Radiography

art and science of making radiographs by the exposure of film to x-rays

Dental radiography

the production of radiographs of the teeth and adjacent structures by the exposure of film to x-rays

Dental radiographer

Any person who positions, exposes, and processes x-ray film

Importance of Dental Radiographs

Enable the professional to identify conditions undetected by naked eye

Benefits of Dental Radiographs

outweighs the risk of small doses of x-radiation

Uses of dental radiographs

Detect, confirm or classify, localize, provide information, evaluate growth and development, illistrate changes, and document lesions/diseases/trauma

Information found on dental radiographs

Missing, extra, and impacted teeth; caries, diseases, and abnormalities

Duties and responsibilities

Positioning, processing, mounting, educating, maintenance, implementation, and ordering

Professional goals

Protection, education, competence, efficiency, production of high quality images and care

Ionization

atoms are neutral when they have an even number of electrons and protons; sometimes they are unbalanced and unequal

Ion

atom that gains or loses electrons and is unbalanced'; always trying to become balanced

ionization

production of ions

Radiation

A form of energy carried by waves or streams of particles through space or a substance.

Radioactivity

The process by which certain unstable atoms or elements undergo disintegration to become balanced

Particulate Radiation

tiny particles of matter that process mass and travel in straight lines at high speeds

4 types of particulate radiation

Electrons (beta/cathode), Alpha particles, protons, and neutrons

Electromagnetic Radiation

The propagation of wavelike energy/particles with no mass; may be human made or occur naturally; Ionizing or non-ionizing

Velocity

the speed of the wave

Wavelength

distance between the waves

frequency

the number of wavelengths that pass a certain point in given time

Long wavelength = ___ frequency

low

Short wavelength = ____ frequency

high

components of x-ray machine

control panel, extension arm, tubehead (tube and apparatus)

Tubehead

tightly sealed, heavy metal housing; contains the x-ray tube that produces dental x-rays

metal housing

surrounds the x-ray tube and transformers, protects tube and grounds high voltage components

insulating oil

surrounds x-ray tube and transformers, prevents overheating

tubehead seal

permits exit of x-rays from tubehead, seals the oil, filters x-ray beam

x-ray tube

heart of generating system

transformer

alters voltage of incoming electricity

aluminum disks

filter out nonpenetrating, longer wavelength x-rays

lead collimator

restricts size of x-ray beam

position-indicating device

aims and shapes the x-ray beam

x-ray tube

A glass vacuum tube - contains components necessary for the generation of x-rays

components of x-ray tube

leaded-glass housing, cathode, and anode

leaded glass vacuum tube

prevents x-rays from escaping in all directions; one area has “window” to permit the x-ray beam to exit the tube and directs toward the aluminum disks, lead collimator

Cathode (neg)

consists of a tungsten wire filament in a cup-shaped holder made of molybdenum; supplies electrons necessary to generage x-rays

Anode (pos)

Wafter-thin tungsten plate embedded in a solid copper rod; converts electrons into x-ray photons

Tungsten target

serves as a focal spot and converts electrons into photons

copper stem

dissipate heat away from the tungsten target

high-voltage circuit

uses 65,000 to 100,000 volts

Transformers

Device used to increase or decrease the voltage in an electrical circuit

Step-down transformer

Decreases voltage from incoming 110- or 220- line voltage to 3-5 volts used by the filament circuit

Step-up Transformer

Increases incoming voltage 110-220 volt line to 65,000 to 100,000 volts used by the high-voltage circuit

Autotransformer

regulates fluctations

Production of X-rays

Electricity from the wall outlet supplies the power to generate x-rays, the current is directed to the filament circuit and step-down transformer in the tubehead

Thermionic emission

The release of electrons

When electrons strike the tungsten target, less than ___ % of the energy is converted to x-rays, the remaining ___ % is lost as heat

1; 99

General radiation

braking radiation (bremsstrahlung)

Braking

sudden stopping of high-speed electrons when they hit the tungsten target in the anode

Characteristic radiation

x-ray photons are produced when electrons replace other eletrons in the inner shell

Primary radiation

x-ray beam that is produced at the target of the anode

Secondary radition

X-radiation created when the primary beam interacts with matter

Scatter radiation

A forum of secondary radiation, the result of a x-ray that has been deflected from its path by an interaction with matter

Quality of radiation

energy or penetrating ability of the x-ray beam, controlled by kilovoltage, X-rays with shorter wavelength have more penetrating power

Quantity

Number of x-rays produced; controlled by milliamperage

intensity

total energy contained in the x-ray beam in a specific area at a given time; affected by the kilovoltage, milliamperage, exposure time, and distance

voltage

potential difference between two electrical charges

When voltage is increased the speed of electrons is ____ from the cathode toward the anode

increased

electrons strike the target with greater force and energy producing a ___ penetrating beam with a ___ wavelength

more; shorter

voltage is measured in

volts or kilovolts

KvP controls

speed and energy of the x-ray beam

Radiolucent

those areas on the film with varying shades of darkness which appears in a range from dark gray to black

Radiopaque

refers to “whiteness” of observable structures on the radiograph

Density

overall darkness or blackness of an image

Density will increase with an increase in exposure factors

milliamperage, kVp, exposure time, and subject thickness-decreases density

When kilovoltage is increased the radiograph will appear ___. density is ___

darker; increased

when kilovoltage is decreased the radiograph will appear ___, density is ____

lighter; decreased

high contrast means

distinct differences between light and darkness and is good for detection of caries

low contract

many shades of gray and is good for detection of periodontal disease

influencing factors of contrast

film contrast, subject contrast, kVp

film contract

inherent qualities within the film that are influenced by the manufacturer

controllable factors that affect film contrast

film processing

Influencing factor of contrast

kVp

kVp controls

the energy or penetrating ability of the x-rays

high kVp

the more easily the x-rays pass through objects in their path, resulting in low contrast and shades of gray

low kVp

high contrast with more areas of black and white

Short scale contrast

shows only two densities, black and white (low kVp, low contrast)