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Image Analysis

Chapter 2

QuestionAnswer
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?