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Contrast & Density
Contrast info, Density info
| Question | Answer |
|---|---|
| An H & D curve demonstrating a steep curve represents film with ______? | High contrast |
| How does the use of grids affect the contrast of a radiograph? | Produces higher contrast |
| Subject contrast is caused by? | Tissue density differences, atomic number, and body part thickness |
| List the body parts in order from less absorbing power to more absorbing power. | Air, Fat, Water, Muscle, and Bone |
| Adding air to a body part ______ its tissue density compared to the structures around it. | Decreases |
| Adding iodine or barium to a body part ______ its tissue density compared to the structures around it. | Increases |
| What is the main controlling factor for radiographic contrast? | kVP |
| The radiation that goes through the patient's body is called? | Exit radiation or remnant radiation |
| Scattered radiation ________ radiographic contrast. | Lowers |
| 3 most common contrast agents | Air, Barium and Iodine |
| Adding air <increases/decreases> radiographic density | Decreases |
| As x-ray photons are absorbed, scattered, or pass through, the intensity of the beam is reduced. this is called _______. | Attenuation |
| ________ refers to the ability of a film to record a wide range of densities. | Film latitude |
| Low energy radiation will result in ______ ____ contrast. | Short scale |
| How will high kvp techniques affect radiographic contrast? | Produce lower contrast |
| The quality of an x-ray beam is determined by? | kVp |
| How will increasing screen speed affect radiographic quality? | Produce higher contrast |
| Which grid ratio should be used to maintain contrast when using over 100 kvp? | 12:1 |
| The number of density difference in a radiograph refers to what? | Scale of contrast |
| How does a small increase indeveloper temperature affect radiographic contrast? | Produces higher contrast |
| Subject contrast will be the lowest with which body habitus? | Hyperstenic |
| What accessory can be used to demonstrate a scale of contrast or test for contrast? | Penetrometer |
| How will an air gap technique affect radiographic contrast? | Produce higher contrast |
| Contrast can be measured from an H & D curve by finding the slope of the ________ ________. | Highest contrast |
| Long wavelength radiation will result in _____ scale contrast. | Short |
| What type of relationship occurs with contrast when mAs increases? | Inverse relationship |
| What type of relationship occurs with contrast when SOD increases? | Inverse relationship |
| What type of relationship occurs with contrast when tube angle increases? | No change |
| Why is contrast needed in a radiographic image? | Makes detail visible. |
| How does an increase in developer temperature affect contrast? | Contrast decreases. |
| As contrast decreases, how is the number of densities in the film affected? | Increases |
| As motion increases, what happens to contrast? | Motion has no effect on contrast. |
| Define contrast. | Difference between adjacent densities. |
| A visible change in kVp is not seen until kVp is changed __ to __%, depending on kVP range. | 4, 12 |
| What are the two types of radiographic contrast? | Film and subject contrast |
| Define film contrast. | The range of densities that the image is capable of recording. |
| Define subject contrast. | Range of differences in the intensity of the x-ray beam after it has been attenuated by the subject. |
| What happens to contrast if collimation is increased? | Decreased contrast |
| Density is one of the two ________ properties comprising visibility of detail. | Photographic |
| Increments of 0.3 changes in optical density numbers represent a ________ or ________ of opacity. | Doubling, halving |
| Image density/brightness on the display monitor is controlled by __________ ________ | Window levelling |
| The ______________ _______ states film density should remain unchanged as long as the intensity and duration of x-ray exposure remains unchanged. | Reciprocity law |
| When kVp ranges 30 - 50, a __ to ___ percent change in kVP can be detected. | 4 to 5 |
| A __ to ___ percent change in kVp is required in the 50-90 kVp range. | 8 to 9 |
| A ___ to __ percent change in kVp is required in the 90 - 130 kVp range. | 10 to 12 |
| The 15 percent rule is somewhat accurate within the range of ___ to ____ kVp. | 60 to 100 |
| The image receptor exposure is always greater at the _________ end. | Cathode |
| The anode heel effect is also more significant when using ____ _____ anodes (12 degrees or less) | small angle |
| The portion of an object with the greatest subject density should be placed toward the ____ end of the tube. | Cathode |
| Radiolucent contrast media (air) will _________ film density. | Increase |
| Radiopaque contrast media (barium, iodine) will _______ film density. | Decrease |
| As relative speed increases, the amount of exposure required to maintain the same film density ____________. | Decreases |
| Film density will _____ when developer solution temperatures ________. | Increase, increase |
| Film density will _____ when developer solution temperatures ________. | Decrease, decrease |
| __________ ____________ controls image contrast. | Window width |
| As the slope of the Dlog E curve increases, contrast is _______. | Increased |
| Low kVp produces ____ subject contrast because most of the low energy photons are absorbed by thicker parts. | Higher |
| With high kVP, subject contrast is _______ because more uniform penetration occurs between thick and thin parts. | Decreased |
| In a fixed kilovoltage system, the kVp is held _______, while the mAs is ______ to achieve appropriate image receptor exposure. | Constant, varied |
| Fixed kilovotage technique systems, _____ patient dose. | Decrease |
| _______________ kVp is the maximum kVp level that will produce images with appropriate contrast, consist within acceptance limits. | Optimal |
| The objective of optimal kVp is to determine the ____kVp and _____ contrast that is within acceptance limits. | Highest, lowest |
| A ________ ____________ x-ray exposure technique system is one where the kilovoltage to be used for a particular projection is varied, depending on measured body part thickness. | Variable kilovoltage |
Created by:
rad1958tech
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