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Recorded Detail
Ch. 30
| Question | Answer |
|---|---|
| ______ is the degree of geometric sharpness or accuracy of the structural lines actually recorded in the image. | Recorded detail |
| Recorded detail is also referred to as: | definition, sharpness, spatial resolution or detail. |
| The primary film/screen unit of resolution is ______. | line pairs per millimeter or cycles per mm. |
| Most human visual acuity is limited to the range of ____ lp/mm. | 5 |
| Digital imaging recorded detail is determined primarily by _____. | matrix size, pixel size and gray scale bit depth. |
| Digital imaging recorded detail is most commonly described in terms of _________. | spatial frequency |
| A shorter wavelength signal (with higher frequency) represents pairs of lines that can be visualized ________. | very close together (high resolution) |
| Low frequency spatial resolution has a longer wavelength (and lower frequency) representing pairs of lines that are _______. | further apart (low resolution) |
| The art of radiography involves controlling the degree of _______ so that it does not interfere with image diagnosis. | unsharpness |
| _______ for digital images can be expressed in terms of three dimensions of the image. | Spatial resolution |
| Spatial resolution describes the ability of an imaging system to accurately display objects in _____. | two dimensions |
| ____________ measure the boundaries of a single image. | Point spread function (PFS), line spread function(LSF) and edge spread function (ESF) |
| In conventional radiography, PFS was referred to as _________. | penumbra or blur |
| The higher the _________, the closer together the sine waves and the closer together the line pairs. | spatial frequency |
| _________ measures the accuracy of an image compared to the original object on a scale of 0 to 1. | Modulation transfer function, |
| _______ is background information that the IR receives. | Imaging noise |
| ______ refers to a lack of sufficient incoming data (photons) for processing. | Quantum noise |
| Another name for quantum noise is ________. | quantum mottle |
| __________ is the sampling of the spatial resolution frequency signal twice from each cycle in digital systems. | Nyquist criterion |
| _______ occurs when the the spatial frequency exceeds the nyquist frequency and the incoming data is sampled less than twice per cycle. | aliasing |
| Resolution affects the image appearance by demonstrating _______ structures. | fine detail |
| ______ may cause an unsharpness of an image. | motion |
| Resolution problems can be fixed by: | 1. eliminate motion 2. reduce OID 3. reduce focal spot size 4. reduce intensifying screen phosphor size and concentration and 5. increase SID |
| Resolution is improved when OID ______ and degrades whenever it ______. | decreases;increases |
| Resolution is improved when SID ______ and degraded when it ______ | increases;decreases |
| The minimum OID should be used to improve ______. | detail |
| The ______ is the distinctly sharp area of a shadow or the region of complete shadow. | umbra |
| The _____ is the imperfect, unsharp shadow surrounding the umbra. | penumbra |
| As focal spot decreases in size, ____ also decreases, thus _______ resolution. | penumbra; increasing |
| Penumbra is increased by _____ of the beam. | attenuation |
| A slow fim/screen combination will demonstrate better ______ than a fast combination. | resolution |
| The resolving power of an intensifying screen depends on what three factors? | phosphor size, phosphor layer thickness and phosphor concentration |
| Quantum mottle is corrected only by increasing ______. | mAs |
| The major factors that limit photostimulable phosphor systems are the _____ and _____. | intensifying screen and scanning system |
| The major factor that limits INDIRECT digital systems is the ______ | size of the detector element |
| The major factor that limits DIRECT digital systems is the ______ | size of the detector element |
| _____ is that which is under the direct control of the patient. | voluntary motion |
| What is the best way to reduce and control voluntary motion? | communication with the patient |
| ______ in not under the conscious control of the patient | involuntary motion |
| Involuntary motion can best reduced by decreasing ________. | exposure time |
| What are methods which can be used to reduce the possibility of motion? | communication, immobilization devices and reduced exposure time |
| Digital imaging systems are dependent on: | matrix size, pixel size, and gray scale bit depth |
| Visualization of _________ is in indication of acceptable resolution | trabecular patterns |
| The z-axis is the gray scale which is represented as the: | depth (depth of information) |
| High spatial resolution represents a high frequency signal that is capable of imaging | smaller objects |
| Low spatial resolution represents a lower frequency signal that can only image | larger objects |
| The focal spot size is a major controller of image resolution because it controls | penumbra |
| High fill factor will produce ______. | high resolution |
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