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RADT 2403 Chapter 9
| Question | Answer |
|---|---|
| A quality radiograph must include: | accuracy of structural lines displayed, sharpness and visibility of anatomic structures |
| Visibility factors of a quality radiograph include: | brightness and contrast |
| What results in a poor-quality digital image because of improper processing due to extreme over exposure to the IR? | saturation |
| What feature provides a numeric value indicating the level of radiation exposure to the digital IR? | exposure indicator |
| Anatomic tissues that attenuate the x-ray beam equally are said to have: | low subject contrast |
| An imaging system that can resolve 10 Lp/mm instead of 6 Lp.mm is said to have: | improved sharpness |
| Unwanted scatter exposure to the IR will likely increase: | fog |
| What is defined as "the range of exposure intensities an IR can accurately detect"? | dynamic range |
| For a given field of view (FOV) a ___ matrix size will result in ___ pixels. | large, more |
| In digital imaging which of the following determines the range of grayscale available for display? | pixel bit depth |
| During digital image display, the contrast can be lowered (decreased) by increasing ___ | window width |
| The ability of an imaging system to distinguish between small objects that attenuate the x-ray beam similarly defines: | contrast resolution |
| Increasing the displayed field of view (FOV) for a fixed matrix size will result in: | increased pixel size |
| Spatial frequency consists of units of: | line pair/millimeter |
| Which of the following reduces contrast resolution? | noise |
| If the dynamic range of an imaging system is 12 bits, how many shades of gray are available? | 4096 |
| Patient radiation dose should be lower when utilizing a newer digital imaging system because of: | Detective Quantum Efficiency (DQE) |
| Detective Quantum Efficiency (DQE) is a measure of: | x-ray absorption |
| The x-ray beam incident on the IR compared to the one incident on the patient: | has less intensity |
| The post-processing method used to allow us to see all shades of gray in an image referred to as: | window width and level |
| Size distortion will be affected by which of the following expect: | kVp |
| Increasing the signal-to-noise (SNR) increases the visibility of anatomic strucutres | true |
| The exposure indicator (EI) of a digital imaging system provides a numeric value that corresponds to the radiation exposure to the IR | true |
| A radiographic image that shows high subject contrast will have more shades of gray than an image with low subject contrast | false |
| The greater the pixel bit depth the greater the number of shades of gray available for image display. Decreasing the bit depth will improve the contrast resolution of a digital image. | false |
| To alter image brightness (density), the ____ is changed | window level |
| Why can an acceptable image be produced with computed radiography (CR) or digital radiography (DR) equipment even when the input exposure was underexposed or overexposed? | wide dynamic range of the digital detector |
| Contrast resolution is the ability to: | distinguish between small objects that attenuate the x-ray beam similarly |
| What occurs if the number of pixels in a matrix decreases and the field of view remains the same? | spatial resolution decreases |
| What is the result of under-penetration? | quantum noise |
| What could be considered 100% contrast? | one black pixel and one white pixel |
| The amount of light emitted from the display monitor is | brightness |
| Which of the following is correct regarding the display feature windowing? | changing the window level will change the brightness level |
| Radiographic contrast | allows visibility of anatomic structures |
| Which of the following contribute to subject contrast? | differences in tissue density, effective atomic number and difference in tissue thickness |
| A radiographic image that has brightness levels that are very similar to each other | has low contrast and has long-scale contrast |
| The distance from the center of one pixel to the center of the one next to it is | pixel pitch |
| Spatial resolution can be increased by: | increasing the pixel density and decreasing the pixel pitch only |
| To measure resolution, a ____ is necessary. | resolution test pattern |
| Which of the following is correct regarding spatial frequency? | small objects have higher spatial frequency and large objects have lower spatial frequency only |
| What is a measure of the imaging system's ability to display the contrast of anatomic objects varying in size? | modulation transfer function |
| The radiographic misrepresentation of either the size (magnification) of the shape of the anatomic part is called | distortion |
| Size distortion is also called | magnification |
| When the image of a structure appears shorter than the actual structure there is | shape distortion |
| What decreases the visibility of anatomic strucutres? | scatter radiation |
| Quantum noise is a result of | too few x-ray photons reaching the IR |
| Which of the following is a method of describing the strength of the radiation exposure compared with the amount of noise apparent in a digital image? | signal-to-noise ratio |
| When the image is distorted, spatial resolution is also decreased | true |
| The higher the detective quantum efficiency (DQE) of a system, the lower the radiation exposure required to produce a quality image | true |
| Decreasing the contrast-to-noise ratio will increase image quality | false |
| The resolution of the monitor used to display the digital image has an enormous effect of spatial resolution | true |
| Because it reduces spatial resolution, it is always best to minimize shape distortion in radiographic imaging | false |
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