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75 Cards in this Set
- Front
- Back
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Radiation |
The emission of energy in the form of waves through space or material. |
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x-radiation |
high-energy electromagnetic radiation |
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x-ray |
form of ionizing radiation |
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Radiology |
science or study of radiation as used in medicine |
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radiograph |
image produced on photosensitive film by exposing the film to x-rays then processing it |
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dental radiography |
the making of radiographs of teeth and adjacent structures through exposure to x-ray |
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Ionizing radiation |
radiation that produces ionization |
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anode |
positive electrode in the x-ray tube
acts as a target for the electrons |
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cathode |
the negative electrode in the x-ray tube
purpose is to supply the electrons necessary to generate x-rays |
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Primary beam |
most penetrating beam produced at the target of the anode |
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Ion |
electrically charged particle |
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Kilovoltage peak |
the x-ray tube peak voltage used during x-ray exposure |
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milliampere |
is 1/1000 of an ampere, a unit of measurement used to describe the intensity of an electric current
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W.C. Roentgen |
Discovered x-rays |
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C. Edmund Kells |
first person to make practical use of radiographs in dentistry |
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Ionization |
process by which electrons are removed from electrically stable atoms |
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Tubehead PID extension arm |
Primary components of a dental x-ray machine |
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99% |
amount of energy lost as heat during the production of x-rays |
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Primary Secondary Scatter |
types of radiation |
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Radiolucent |
term for structures that appear dark on a processed radiograph
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Radiopaque |
term for structures that appear light on a processed radiograph |
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kVp |
exposure factor that controls contrast |
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Density |
the overall darkness of a processed radiograph |
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Ionization |
name of the process for the harmful effects of x-ray |
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latent period |
period of time between x-ray exposure and the appearance of systems |
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Genetic effect |
radiation that is passed on to future generations |
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The Traditional or Standard System Systeme Internationale |
system that is used to measure radiation |
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5.0 rems/year |
maximum permissible dose of radiation for occupationally exposed persons |
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purpose of collimator |
reduce exposure of the primary beam and restrict the size of the primary beam |
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Aluminum filter |
removes the low energy, long wavelength rays |
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Purpose of personnel monitoring |
record the amount of radiation the operator receives |
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purpose of equipment monitoring |
check for radiation leakage |
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ALARA concept |
"as low as reasonably achievable" |
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Purpose of PID |
to direct the x-ray beam |
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Bremsstrahlung radiation |
the primary type of radiation produced in the x-ray tubehead |
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nuclear binding energy |
energy that hods that |
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electron binding energy |
energy holding electrons in their shells
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Electron |
negatively charged particle in the atom |
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electromagnetic radiation |
made up of photons that travel through space at the speed of light in a straight line with a wavelike motion
includes: x-rays, visible light, radar, radio, and television waves |
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shorter wavelength of the x-ray |
the greater it's energy |
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Why are shorter wavelengths especially useful in dentistry |
because of their high energy, short wavelengths can penetrate matter more easily than longer wavelengths |
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Components of the tubehead |
The housing insulating oil tubehead seal x-ray tube transformer |
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lead collimator |
a metal disc with a small opening in the center. It is located inside the PID in the path of the x-ray beam. The small opening forms the size and shape of the x-ray beam as it leaves the tubehead |
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Aluminum filter |
is a .5mm thick sheet located inside the PID in the path of the x-ray beam that filters out the nonpenetrating longer wavelength radiographs |
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PID |
open ended lead lined cylinder that extend from the opening of the metal housing |
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x-ray tube |
heart of the x-ray generating system
the vacuum environment allows electrons to flow with minimum resistance between the electrodes |
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short PID |
8 inches long |
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long PID |
16 inches long |
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True |
True/False
The long PID is more effective in reducing the exposure than a short one because there is less divergence of the beam |
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Extension Arm |
encloses the wire that runs between the tubehead and the control panel
used to position the tubehead
can be turned 360 degrees horizontally |
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Master Switch |
used to turn the machine on and off |
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Exposure button |
controls the flow of electricity to generate the x-rays. The timer is electronically controlled to provide precise exposure time and x-rays are only generated while the exposure timer is being pressed |
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impulses |
measures exposure time
(60 impulses=1second) |
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Primary radiation |
less penetrating made up of the x-rays coming from the target of the x-ray tube aka the useful beam or primary beam |
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mAs |
unit of measurement used to measure density |
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kVps |
unit of measurement used to measure contrast |
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The National Council of Radiation Protection and Measurement |
determines radiation effects and tolerable levels for humans |
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90 kVp setting |
requires less exposure time and produces an image with low contrast (more shades of gray)
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70 kVp setting |
requires a slightly longer exposure time and produces an image with high contrast |
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Factors that influence sharpness |
Focal spot size Film Composition Movement |
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Distortion |
refers to the disproportionate change in the size of images that is caused by excessive or insufficient vertical angulation |
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Magnification |
refers to proportionate enlargement of a dental image |
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Somatic effect |
refers to the body and is not passed down to other generations |
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Critical organs at risk to radiation |
skin thyroid gland lens of the eye bone marrow (small lymphocytes) |
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Traditional units of radiation measurement |
1. Roentgen (R) 2. radiation absorbed dose (rad) 3. roentgen equivalent in (hu)man (rem) |
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SI units of radiation measurement |
1. coulombs per kilogram (C/kg) 2. the gray (Gy) 3.sievert (Sv) |
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Background radiation |
comes from natural sources such as radioactive materials in the ground and cosmic radiation from space |
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Maximum Permissable Dose of occupationally exposed radiation |
100 mrem/week 5000mrem/year, 5.0rems/year, .05Sv/year
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Maximum Permissable Dose for nonoccupationally exposed radiation |
500mrem/year book says .1mrem/year |
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Fast speed film |
very effective way of reducing a patient's exposure to x-radiation
available for both intraoral and extraoral radiography |
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3 types of monitoring devices |
1. film badge 2. pocket dosimeter (pen style) 3. thermoluminescent device (TLD) |
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Dosimeter |
measures occupational exposure |
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Rules of radiation exposure |
1. never stand in direct line of the primary beam 2. always stand behind a lead barrier or a proper thickness of drywall. If a barrier is not available, stand at a right angle to the beam 3. never stand closer than 6ft from the x-ray unit during an exposure unless you are behind a barrier |
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Erythema |
earliest sign of radiation overexposure |
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Examples of cumulative radiation |
1. cataracts 2. leukemia 3. cancer |
