oral radiology ch 1-3 extended

radiology

• is the science or study of radiation as used in medicine

• a branch of medical science that deals with the use of x-rays, radioactive substances, and other forms of radiant energy in the diagnosis and treatment of disease

radiograph

• a photographic image produced on film or computer by the passage of x-rays through teeth and related structures

why are dental images important in dentistry?

• radiographs (images) enable diagnosis

• dental images enable the dental professional to identify many conditions that may otherwise go undetected and to see conditions that cannot be identified clinically

Wilhelm Conrad Roentgen

• roentgen was experimenting with vacuum tubes and fluorescent screen when he discovered an unknown glow

• print of his wife’s hand was the first known image taken with x-ray technology

C.Edmund Kells

• introduced the paralleling technique in 1896

• was the first to use radiographs in the dental practice

radiation

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

• the emission and propagation of energy through space or a substance in the form of waves/particles

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

x-radiation

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

x-ray

• a beam of energy that has the power to penetrate substances and record image shadows on receptors

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 by the exposure of a receptor to x-ray

dental radiographer

• any person who positions, exposes, and processes dental x-ray image receptors

image

• a picture or likeness of an object

image receptor

• a recording medium; examples include x-ray film, phosphor plate, or digital sensor

imaging, dental:

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

Coolidge

developed first x ray tube

Fitzgerald

• went on to improve long-cone paralleling technique

McCormack

• used paralleling technique in practical dental radiography

Morton

• exposed first dental radiograph in the united states (living patient)

Price

• introduced bisecting tehnique

Raper

• wrote first dental text; introduced bite-wing tecchnique

Rollins

• wrote first paper on the danger of x-radiation

Walkhoff

• exposed first dental radiograph

in which shell do electrons have the greatest binding energy?

k shell

what type of electrical charge does the electron carry?

negative

which terms describes two or more atoms that are joined by chemical bonds

molecule

which statement describes ionization

• is the production of ions, or the process of converting an atom into ions.

• ions are known as atoms that have undergone the process of losing or gaining electrons, therefore becoming electrically unbalanced

which is not a type of particle radiation

nucleons

which term describes the process by which unstable atoms undergo spontaneous disintegration in an effort to attain a more balanced nuclear state

radioactivity

which is not a type of electromagnetic radiation

electron

which statement is incorrect?

wavelength is the distance between waves

which statement is incorrect

x-rays travel at the speed of sound (they actually travel at the speed of light)

which statement is correct

x-rays have more energy than visible light does

be able to identify and label x-ray tube

• step up transformer

• step down transformer

• cathode

• anode

• aluminum disk

• tubehead seal

• position indicating device

• unleaded glass

• insulating oil

• metal sealing

• lead collimator window

which regulates the flow of electrical current to the filament of the x-ray tube?

• low-voltage circuit

which is used to increase the voltage in the high voltage circuit?

step up transformer

which does not occur when the high voltage circuit is activated

x-rays travel from filament to target

which is the location where x rays are produced

positive anode

which is the location where thermionic emission occurs

negative cathode

which accounts for 70% of all the x-ray energy produced at the anode?

general radiation

which occurs only at 70 kV or higher and accounts for a very small part of x-rays produced in the dental x-ray machine?

characteristic radiation

which describes primary radiation?

radiation that exits the tubehead

which describes scatter radiation

radiation that has been deflected from its path by interaction with matter

which type of scatter occurs most often with dental x-rays?

compton

Known at the “binding energy” of an electron

• electrons are maintained in their orbits by electrostatic force between positive nucleus and negative electrons

• the closer the electron shell is to the nucleus, the stronger the bind will be

radioactivity

• is the process by which certain unstable atoms or elements undergo spontaneous disintegration or decay

• the dental profession does not deal with radioactivity

cathode

• (-) CATNAP

• supplies the electrons necessary to generate x-rays

• cathode rays are streams of high-speed electrons that originate in an x-ray tube

• tungsten filament produces electrons when heated

insulating oil

• surrounds x-ray tube and transformers, prevents overheating

anode

• (+) CATNAP

• consists of a wafer-thin tungsten plate embedded in a solid copper rod

• converts electrons into x-ray photons

early production of dental x-rays

1. electricity from the wall outlet supplies the power to generate x-rays

2. the current is directed to the filament circuit and step-down transformer in the tubehead

3. the filament circuit uses 3-5 volts to heat the tungsten filament in the cathode

4. thermionic emission occurs, and the release of electrons

5. electrons stay in an electron cloud until the high-voltage circuit is activated

primary radiation

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

• what is produced and comes out of PID

secondary radiation

• x-radiation created when the primary beam interacts with matter

• is what is not used from the primary radiation and hits outside of the target

scatter radiation

• a form of secondary radiation, the result of an x-ray that gas been deflected from its path by an interaction with matter

• scattered radiation is when the radiation is deflected off of something

compton scatter

• ionization takes place and x-rays have been made, but the x-ray photon loses energy and focuses in a different direction. does not help in taking a useful radiograph

• the ejected electron is termed a Compton electron

free radical formation

• occurs when x-ray photons are absorbed by water within a cell

• the free radicals combine to form toxins that damage cells

• ONLY creates a toxin when it interacts with water via ionization

indirect theory

• x-ray photons are absorbed within the cell and cause the

radiosensitive organs

• lymphoid tissue

• bone marrow

• testes

• intestines

radioresistant organs

• salivary glands

• kidney

• liver

critical organ

• an organ that, if damaged, diminishes the quality of a person’s life

• critical organs exposed during dental radiographic procedures include

  • skin

  • thyroid gland

  • lens of the eye

  • bone marrow

somatic cells

are all of the cells in the body except reproductive cells

the latent period in radiation biology is in the time between

• exposure to x-radiation and clinical symptoms

a free radical

• combine with molecules to form toxins

direct radiation injury occurs when

x-ray photons hit critical targets within a cell

indirect radiation occurs when

• x-ray photons are absorbed and form toxins

which relationship describes the response of tissues to radiation?

linear, nonthreshold

which statement is incorrect?

long-term effects are seen with small amounts of radiation absorbed in a long period

radiation injuries that are not seen in the person irradiated but that occur in future generations are termed

genetic effects

what is most susceptible to ionizing radiation

small lymphocyte

The sensitivity of tissues to radiation is determined by:

mitotic activity, cell differentation, and cell metabolisim

Which of the following is considered radioresistant?

Mature bone cells

An organ that, if damaged, diminishes the quality of an individual's life is termed a:

critical organ

The traditional unit for measuring x-ray exposure in air is termed:

the roentgen

what is the greatest contributor to artificial radiation exposure

medical radiation

the amount of radiation exposure an individual receives varies depending on:

film speed, collimation, technique, exposure factors