Term
Put material in order of most radiolucent (Black on the radiograph) to more radiopaque (white on radiograph)
- Bone/mineral
- Fat
- Metal/Contrast material
- Soft Tissue/Fluids
- Air/Gas
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Definition
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Term
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Definition
| When two objects are superimposed over one another, changing the visible opacity |
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Term
| Describe boarder effacement |
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Definition
| The boarder of an object becomes convoluted when it's margin lies against another object having a similar radiopacity |
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Term
| Are structures closer or further away from the FILM magnified? |
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Definition
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Term
| If you are shown a Right Lateral view of an animal, which side is down on the table? |
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Definition
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Term
| What is characteristic radiation? |
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Definition
A high speed electron from the cathode collides with an e- orbiting a nucleus in the anode. If the energy of the incoming high speed electron exceeds the energy of the e- orbiting the nucleus, it will eject that electron (called a recoil electron)
Replacement of the ejected electron from an outer shell leads to the formation of characteristic radiation
[image] |
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Term
| Bremsstrahlung is the main e- interaction when taking X-rays, describe this interaction |
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Definition
An incoming electron from the cathode does not have eneough energy to knock out an orbital electron in the anode, however it does come close to the nucleus. This close encounter causes the incoming e- to lose energy and change direction. That loss in energy is emitted as an X-ray photon.
An incoming e- from the cathode can also directly impact the nucleus, losing all of its energy, and emitting an X-ray photon. |
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Term
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Definition
| Quantity of X-rays produced |
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Term
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Definition
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Term
| What does kVp stand for, and what does it dictate? |
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Definition
Kilovoltage potential
Dictates the maximum possible kinetic energy of the e- flowing towards the anode |
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Term
[image]
Which radiograph had the higher mAs setting? kVp is 40 for both |
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Definition
Right side has higher mAs
mAs too low and the film is underexposed (Lighter)
mAs too high and the film is overexposed (Darker) |
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Term
| Leaving mAs the same, and increasing the kVp will do what to the radiograph? |
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Definition
| Decrease the contrast, because of increased shades of grey |
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Term
| What is X-ray attenuation? |
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Definition
| Decrease in the intensity of an X-ray as it passes through matter, either through absorption or scatter |
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Term
| What is coherent scattering? |
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Definition
Photon interacts with object and changes its direction
No change in energy, and no absorption
creates film fog
In patient
[image] |
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Term
| What is the photoelectric effect? |
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Definition
Complete absorption of the X-ray photon, by removing a photoelectron from a shell (ionization)
A transitional electron takes its place and gives off characteristic radiation, however there is not enough energy for it to leave the body
This effect increases with high atomic number materials and low energy Xrays - gives contrast!
[image] |
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Term
| What is the compton effect? |
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Definition
Xray photon ejects a free electron from an outer shell, causing the photon to scatter. Opposite to the photoelectric effect, this scattered photon will reach the radiograph and not be completely absorbed.
This creates film fog and is a potential saftey hazard. That's why there's lead aprons, duh.
This effect increases with low atomic numbers and high energy Xrays - reduces image quality
In patient
[image]
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Term
| Degree of X-ray absorption depends on what factors? |
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Definition
- Effective atomic number of each tissue
- Density of specific gravity of each tissue
- Thickness of tissue
- Photon energy (kVp) |
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Term
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Definition
| The photosensitive portion of the film. It contains a sweet sweet gelatin and silver halide crystals |
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Term
| Name an advantage and a distadvantage of 'fast film' |
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Definition
Advantage - requires less radiation, less exposure to the patient, great for thicker body parts
Disadvantage - loss of image resolution, less latitude |
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Term
| What is low contrast film generally used for? |
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Definition
| Soft tissues - thorax and abdomen |
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Term
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Definition
Film's inherent ability to produce shades of grey
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Term
| Characteristics of a low latitude film |
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Definition
Has a narrow range of acceptable exposures
Produces high contract images |
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Term
| Describe a high latitude film |
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Definition
Higher range of acceptable exposures
generally a low contrast film |
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Term
| what type of crystals are in intensifying screens? |
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Definition
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Term
| What is non-screen x-ray film? |
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Definition
Those with emulsions more sensitive to direct exposure of X - rays.
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Term
| What are Screen type x-ray films? |
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Definition
Those with emulsions more sensitive to blue [standard] OR green [rare earth] light.
Emitted when X-rays strike the intensifying screens.The X-ray photons are converted to visible light photons. |
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Term
| What does the "quality" of an x-ray beam refer to? |
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Definition
| Penetrating power of the beam, proportional to the x-ray energy (kVp) |
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Term
| What were the three photon interactions with MATTER discussed? |
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Definition
Coherent scattering - Photon interacts with object and changes its direction. No absorption and no change in energy
Photoelectric effect - Complete absorption of photon, characteristic radiation is given off. Most likely to occur with low energy photons and elements with high atomic numbers
Compton (throwing up my set) effect - Incoming photon ejects an outer shell electron, and the photon gets scattered |
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Term
| What are some methods to reduce scatter radiation? |
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Definition
- Collimation - narrow the beam
- Lower kVp
- Tissue compression
- Grids
- Air gap |
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Term
| When is maximum contrast obtained when using barium or iodine? |
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Definition
| When the x-ray photon energy is just about the k-edge of the absorber (barium or iodine) |
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Term
| Why does low kVp create high contrast images? |
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Definition
Because, science!!
And, the photoelectric effect. Photons get absorbed by the tissue more readily = less penetration
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