Stack #132647 Word Scramble
D T Y I N S E
|
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
| Question | Answer |
| What is the ratio of light incident on the film to amount of light transmitted through the film? | radiographic density (optical density) |
| How is resolution measured? | By using a resolution grid, resolution is measured in lines per millimeter (lp/mm) |
| What change in KVP is needed to make a visible change in contrast? | 4-12% |
| What is different degrees of absorption in adjacent tissues that result in image contrast? | differential absorption |
| How does KVP relate to differential absorption? | Differential absorption increases as the KVP is decreased; conversely, as KVP increases, more photons pass through and differential absorption decreases |
| How does tissue thickness affect density? | There is an inverse relationship; as tissue thickness, average atomic number, and/or tissue density increases, radiographic density decreases |
| What effect does halving the SID have on density? | Density is increased 4 times |
| How does SID affect recorded detail? | SID is directly proportional to recorded detail. As SID increases, recorded detail increases and vice versa. This is because shorter SID's causes an increase in magnification, thus causing a decrease in recorded detail |
| What is considered the useful range of optical densities? | 0.25 to 2.5 |
| What term means the misrepresentation of the size or shape of a structure recorded in the radiographic image? | distortion |
| What is the primary controlling factor for contrast? | KVP |
| Which of the two types of contrast is a product of low KVP? | Short scale contrast |
| how does increasing filtration affect contrast? | Contrast is decreased slightly because filtration increases the average photon energy of the beam |
| How does beam restriction affect density? | It reduces the amount of scatter radiation and therefore, reduces the overall density of the image. |
| Why should KVP not be used to control density? | changing KVP also changes contrast |
| What is the rate at which x-ray energy is transformed into light in an intensifying screen? | conversion efficiency |
| What is the sharpness of the structural lines as recorded in the radiographic image? | recorded detail |
| How does SID affect size distortion? | As SID increases, size distortion decreases |
| When making contrast changes on a radiograph, what changes in KVP should be made? | Changes should be made in increments of 8 or 15% |
| How does the focal spot size affect recorded detail? | There is an increase in recorded detail as focal spot size decreases |
| What refers to the random nature in which x-rays interact with image receptor and occurs with the use of high speed screens with very low mas and high KVP and causes a grainy appearance of the image? | quantum mottle |
| How does mas affect contrast? | Mas alters density of image and therefore affects contrast |
| What is the unsharpness that is an inherent part of every radiographic image due to the position and shape of anatomic structures within the body? | inherent object unsharpness |
| Which of the two types of contrast exhibit wide exposure latitude? | Long scale contrast |
| What are the two factors that control size distortion (magnification)? | SID and OID |
| Which formula should be used to maintain density when making distance changes? | Density maintenance formula: MAS1/MAS2=D1(D1)/D2(D2) |
| How does film processing affect density? | Density increases as developer temperature, immersion time, or replenishment rates increase: contaminated developer will decrease density |
| What effect does doubling the SID have on density? | Density is reduced to 1/4 |
| How does OID affect size distortion? | As OID increases, size distortion increases |
| Do filters have an effect on density? | Because filtration alters beam intensity, density decreases slightly with increases in filtration |
| What is the controlling factor of density? | Mas |
| What is the misrepresentation (elongated or foreshortened) of the shape of the structure recorded as compared to the actual shape of the structure? | shape distortion |
| How does tighter collimation affect contrast? | tighter collimation reduces the number of photons available, thus reducing the amount of scatter and increasing contrast (shortens the scale of contrast) |
| What is the imperfect unsharp shadow caused by size of the focal spot (replaces the terms penumbra and geometric unsharpness)? | focal spot blur |
| What factors secondarily influence density? | KVP, distance, beam restriction, anatomic part, grid, film/screen combination, processing, anode heel affect |
| Because of the anode hill effect, density is less at which end of the x-ray beam? | Anode (because of absorption of x-rays by the "heel of the anode") |
| What is the ability to image an object with accuracy? | resolution also called recorded detail |
| What are the two types of distortion? | size and shape |
| What are the two types of contrast seen in medical radiography? | Long scale (low contrast), Short scale (high contrast) |
| What states that the blackening on the film remains constant as long as MAS remains the same and usage of mA and time combinations? | Reciprocity Law |
| What percent change in MAS makes a visible difference in density. | 30% |
| What is the overall blackening of the film from the black metallic silver deposited in the emulsion? | radiographic density (optical density) |
| What is the absorption of x-rays in the heel of the anode which results in decreased x-ray intensity of the anode side of the central ray? | heel affect |
| What are some alternate terms for resolution? | detail, sharpness, definition and resolving power |
| How can distortion be reduced? | By proper alignment of the tube, part and film (centering, keeping object parallel with fim and as close as possible |
| What is the enlargement of the recorded image as compared to the actual size of the structure? | magnification |
| How does increasing grid ratio affect density? | as grid ratio increases, density decreases because grids absorb scatter that would otherwise reach the image receptor |
| What factors cause elongation of an object? | misalignment of the tube or film |
| What factor causes foreshortening of the radiographic image? | misalignment of the part |
| How does OID affect recorded detail? | OID is inversely related to recorded detail. Recorded detail improves as OID decreases |
| Which scale of contrast has many shades of gray? | Long scale (low contrast) |
| Changing peak KVP by what percentage will have the same effect on density as doubling the MAS or halving the MAS? | 15% |
| Increasing or decreasing the contrast does what to density? | density remains the same |
| What is foreshortening of an object? | foreshortening projects the object so it looks shorter than it really is |
| What is elongation of an object? | elongation projects the object so it appears to be longer than it really is |
| How do intensifying screens affect density? | As the speed of the intensifying screen increases, density increases |
| What formula is used to calculate size distortion? | MF = SID/SOD (MF=magnification factor) |
| What effect does SID have on density? | As SID increases, density decreases and vice versa (according to the inverse square law) |
| Which scale of contrast has few shades of gray with many black and white images? | Short scale (high contrast) |
| Which of the 2 contrast factors should be standardized? | Image receptor (film) contrast |
| How can a radiographer reduce motion blur? | Use the shortest possible exposure time; give proper breathing instructions; use restraining devices; use a large SID; use a small OID |
| What is the difference between adjacent densities within the radiographic image? | radiographic contrast |
| What determines subject contrast? | size, shape, and attenuating characteristics of the material being irradiated |
| How does KVP affect density? | Directly, as KVP increases density increases because penetrability increases so more photons are reaching the IR |
| What factors compose radiographic contrast? | Image receptor (film) contrast and subject contrast |
| What effect do grids have on contrast? | improves contrast by removing scatter before it reaches the film which results in a shorter scale of contrast |
| What is most often the cause of motion blur? | patient motion; motion of the x-ray tube is not a problem |
| What influences image receptor (film) contrast? | Characteristics of the film and processing |
| What is the enlargement of the recorded image as compared to the actual size of the structure? | size distortion |
| What is the loss of radiographic quality caused by movement of the patient or x-ray tube during exposure? | motion blur |
| What is the exception to the Reciprocity Law? | Extreme exposure times (more than 10s or less than 10ms with use of intensifying screen |
| What is the region of the anode target where electrons interact to produce x-rays? | focal spot |
| The 15% rule can be used to do what? | increase/decrease density and maintain density while increasing or decreasing contrast |
Created by:
quietone055
Popular Radiology sets