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Image Analysis
Chapter 2
| Question | Answer |
|---|---|
| The light collected and converted to an electrical signal by the photomultiplier tube (PMT) during CR image sampling is then sent to the _____ to be digitized. | ADC (analog-to-digital converter) |
| What is the location on a histogram graph of air/gas? | Right |
| What is the location on a histogram graph of background values? | Far Right |
| What is the location on a histogram graph of bone? | Center |
| What is the location on a histogram graph of contrast/metal? | Left |
| What is the location on a histogram graph of fat? | Right |
| What is the location on a histogram graph of soft tissue? | Center |
| All of the following may result in histogram analysis errors except | Motion |
| All of the following are guidelines for producing optimal image histograms except | use the smallest possible IR and cover at least 50% of it. |
| The exposure indicator number represents all of the following except the | Measure of dose to the patient |
| At what level is the exposure indicator reading taken on the VOI? | halfway between S1 and S2 |
| When is the examination or body part selected when using the DR system? | Before the radiation exposure |
| All of the following are true about histogram analysis errors except | fog values outside the exposure field, but included in the VOI, do not cause widening of the histogram. |
| All of the following are true about windowing except | window level adjustments change the contrast of the image. |
| An exposure recognition field algorithm is applied to the image data to | 1, 2, 3 |
| Saturation indicates | Overexposure of the IR |
| If the image histogram is wider than the LUT’s histogram, all of the following are true except the algorithm would (choose the false statement) | Widen the histogram |
| Appropriate scatter radiation control methods include which of the following? | 1, 2, 3, 4, and 5 |
| Histogram analysis errors for all digital systems include all of the following except | exposure of less than 30% of the IR |
| When an image resembles a double exposure, the type of artifact demonstrated is a(n) _____ artifact. | phantom image |
| Which of the following statements are true? 1. the movement of an image histogram, left to right, will adjust image brightness. 3. changing the shape of the histogram will affect image contrast. | 1 and 3 only |
| n a cassette-less DR imaging system, 1. the correct examination is chosen before the exposure. 2. thin film transistors collect the electrical charge created in the LUT. 3. thin film transistors contain detector elements. | |
| If a projection does not differentiate the densest and thickest structures in the VOI, adjusting the _____ is necessitated. | kVp |
| Exposure indicators 1. are used to create the histogram. 2. denote the quantity of photons that strike the IR. 3. are used to determine dose to the patient. 4. vary from one manufacturer to another. | 2 and 4 only |
| The anode heel affect 2. is a variation in photon intensity across the exposure field. 3. occurs because the heel of the anode absorbs photons. | 2 and 3 only |
| Technical considerations when imaging obese patients include all of the following except: 3. mAs should be doubled for every 2 cm of added tissue. 4. kV should be increased by 2 for every 2 cm of added tissue. | 3 and 4 only |
| The amount of light produced in each pixel in the matrix is _____ to the amount of energy that was _____ in that area of the IP during the acquisition process. | equivalent; stored |
| Best practice guidelines for the use of automatic exposure control include all of the following except | |
| Underexposed projections that require repeating are identified by which of the following: 1. quantum noise is present. 2. the VOI demonstrates a loss of contrast resolution. 3. The EI number indicated less than optimal exposure and no histogram | 1, 2, and 3 |
| Additive disease processes that would require at least a 35% increase in mAs include all of the following except | Paget's Disease |
| Quantum noise can affect edge discrimination and contrast resolution. The only way to decrease quantum noise is to increase the IR exposure by 1. increasing kV. 2. increasing mAs. 3. decreasing kV. 4. decreasing mAs. | 1 and 2 only |
| Total saturation is seen when _____ the ideal IR exposure is reached. | eight to 10 times |
| Technologists can assist the exposure field recognition process when making multiple exposures on one IR by 1. masking the unused portion of the IR with lead sheets. 2. ensuring the body part is centered within each exposure field. 3. increasing | 1, 2, 3, and 4 |
| Which of the following patient conditions demonstrates high subject contrast? | Dense Bones |
| Which of the following patient conditions demonstrates low subject contrast? | High Fat Content |
| Which of the following patient conditions demonstrates low subject contrast? | Fluid retention cause by disease |
| Which of the following patient conditions demonstrates low subject contrast? | Obesity |
| Which technical factor listed below is the primary controlling factor for exposure? | mAs |
| Which of the following technical factors is primarily used to regulate contrast? | kVp |
| What percentage of kVp adjustment doubles the exposure? | 15% |
| An AP abdomen projection was obtained using 85 kVp at 10 mAs. The resulting image demonstrated excessively low contrast, although the brightness was acceptable. What new technique could be used to obtain the projection with equal exposure but higher cont | 72 kVp at 20 mAs |
| What is the technical adjustment required with the patient condition of emphysema? | -8% kVp |
| What is the technical adjustment required with the trauma device of a small to medium plaster cast? | +5-7 kVp or +50%-60% mAs |
| What is the technical adjustment required with the trauma device of a wood backboard? | +5 kVp or +25%-30% |
| What is the technical adjustment required with the patient condition of ascites? | +50-75% mAs |
| What is the technical adjustment required with the patient condition of pleural effusion? | +35% mAs |
| What is the technical adjustment required with the postmortem image of the head, thorax, and abdomen? | +35%-50% mAs |
| What is the technical adjustment required with soft tissue demonstration of foreign object? | –15-20% kVp |
| What is the technical adjustment required with the patient condition of osteoporosis? | –8% kVp |
| A PA chest projection was obtained using a grid with a recommended 40-inch focal range with a 72-inch SID. Where would the grid cutoff be demonstrated on the projection? |
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