Term
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Definition
| The shorter the group's wavelength, the stronger the energy. KEY: x-rays produce ionization, others do not. |
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Definition
| The ejection of an electron from an atom. Produces charged ion pairs of free radicals. |
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Definition
| Movement of elections (-) along a wire toward a (+) charge which changes direction 60 times per second. |
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Definition
1 Second = 60 impulses of x-rays
1/4 second - 15 impulses of x-rays |
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Term
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Definition
| Amps (mA) describe the number of electrons flowing. |
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Definition
| Volts (kVp) describes the potential differences between the negative and positive and therefore, the speed or force of the moving electrons toward the positive charge. |
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Definition
| Number of x-ray photons given off in a period of time. |
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Term
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Definition
| Penetrating nature/power of the x-ray photons (involves wavelengths). More penetrating = shorter waves |
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Definition
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Term
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Definition
number of photons increase (quantity)
heats filament |
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Term
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Definition
| Number of photons increase (quantity) |
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Term
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Definition
Number of photons increase
Shorter wavelengths (more penetration)
(quantity and quality) |
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Term
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Definition
Number of photons decrease
Removes softer dangerous photons
Hardens the beam
(quantity and quality) |
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Term
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Definition
Number of photons decrease as beam spreads.
(quantity) |
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Term
| What two things affect penetration (quality)? |
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Definition
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Term
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Definition
More photons = more density (energy = blackness)
Affected by: mA, exposure time, kVp, filtration decrease, distance decrease |
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Term
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Definition
A SHORT SCALE OF CONTRAST: mostly black and whites (high visual contrast)
-results form less kVp and aluminum
A LONG SCALE OF CONTRAST: many shades of gray (low visual contrast)
-results from more kVp and aluminum |
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Term
| What two things affect contrast? |
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Definition
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Term
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Definition
Tubehead: increases # of photons
Film Density: increases density |
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Term
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Definition
Tubehead: increases # of photons
Film Density: increases denstiy |
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Term
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Definition
Tubehead: Increases # of photons/ penetration
Film Density: Increases density
Film Contrast: long scale/many grays |
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Term
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Definition
Tubehead: decreases # of photons, removes soft photons, increases % of hard/soft , safer beam
Film Density: decreases
Film Contract: long scale/ many grays |
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Term
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Definition
Tubehead: decreases # of photons
Film Density: decreases density |
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Term
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Definition
These produce the sharpest images with the least magnification:
-small focal spot
-short object-to-film distance (OFD)
-large target-to-film distance (TFD) or (SFD)
-Film and tooth parallel
-Beam perpendicular to film |
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Definition
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Definition
If distance is doubled or halved, the original energy changes by a factor of 4.
i.e. 3 feet to 6 feet inversely from from 4 rads to 1 rad.
*remember the closer you are the more rads you absorb* |
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Term
| What does a double exposure x-ray look like? |
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Definition
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Term
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Definition
| anterior teeth are blurred and thin |
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Term
| Panorex too far posterior |
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Definition
| anterior teeth are blurred and wide (pudgy) |
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Term
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Definition
| note reverse curve of occlusion ; condyles off side of image |
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Term
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Definition
| condyles off top of image |
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Term
Panorex
Imposing Air Space |
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Definition
| tongue not placed against palate |
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Term
Panorex
Imposing Spinal Shadow |
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Definition
| patient slumped forward at an angle |
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Term
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Definition
| Developer -> Fixer -> Rinse -> Dry |
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Term
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Definition
| silver halide (Bromide) crystals on both sides of film |
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Term
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Definition
| (Elon and Hydroquinone) turns only exposed crystals to metallic silver |
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Term
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Definition
| (Sodium Thiosulfate) removes undeveloped (including unexposed) crystals |
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Term
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Definition
| exhausted fixer or poor replenishment, after time, problem is poor wash |
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Term
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Definition
1) Direct (CCD) vs Indirect (PSP Photo-stimuable-phosphor), 2) digital requires less radiation than any film available
3) film has higher resolution that digital |
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Term
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Definition
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Term
| Biological sensitivity to radiation |
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Definition
1) Rapid turnover or mitosis rate of cells increases tissue damage
2) undifferentiated cells have increase damage (WBCs) |
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Term
| Why are children more sensitive to radiation? |
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Definition
| Rapid cell mitosis associated with child's growth |
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Term
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Definition
| time between x-ray exposure and maximum damage observed |
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Term
| Somatic vs. genetic effects |
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Definition
| Genetic effects are only those that can be passed to future generations |
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Term
| Which tissue has the most sensitivity to radiation? |
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Definition
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Term
| Which tissue has the least sensitivity to radiation? |
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Definition
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Term
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Definition
| Adverse reaction of the body to x-radiation never return exactly to original state, therefore, accumulating to some degree over a lifetime. |
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Term
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Definition
Old Units: Roentgen
S.I Units (new): Coulomb/Kg |
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Term
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Definition
Old Units: Rad
S.I Units: Gray |
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Term
MPD
Dose Equivalent in man |
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Definition
Old Units: Rem
S.I Units: Sievert |
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Term
| MPD Occupational (Old and New) |
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Definition
5 rem/ year (old)
.05 Sv./ year (new) |
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Term
| MPD Non-occupational 1/10 (fetus of auxiliary) Old and New |
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Definition
.5 rem/ year (old)
.005 Sv. / year (new) |
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Term
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Definition
| There is always a risk from x-radiation, even in small amounts. Practitioners must weigh possible effects against possible patient benefit |
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Term
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Definition
| Radiographs should be ordered on an individual basis after a historical and clinical examination of the patient. |
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Term
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Definition
| As Low As Reasonably Achievable |
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Term
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Definition
most effective method of protection. each alphabetical film group is 2 times faster than the previous film group and needs half as much radiation exposure.
EXAMPLE: D- speed needs half as much exposure as C-speed and E-speed or E-plus needs half as much as D-Speed. |
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Term
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Definition
| panoramic intensifying screens reduce the amount of radiation ( 3 to 4 BWX) |
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Term
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Definition
| Lead washer sizes beam and reduces scatter. Beam size at the patient's face can be no larger than 2.75 inches. Collimator reduces patient dose. |
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Term
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Definition
| reduces the area of patient's skin surface exposed by 50% to 65% over round |
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Term
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Definition
| must have at least 1.5mm of total aluminum filtration for up to and including 70 kVp. Requires 2.5mm if machine can function above 70 kVp |
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Term
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Definition
| Less volume of tissue is irradiated if long cone is use |
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Term
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Definition
| wall is mandatory if operator cannot stand at least 6 feet from the scatter source (measured from the patient's head). Walls do not necessarily require lead lining, |
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Term
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Definition
| absorbs 90% of the scatter that would have reached the reproductive tissue. Lead equivalent of . 25mm |
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