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RADT 311 Unit 2
| Question | Answer |
|---|---|
| ____________ requires sufficient brightness, sufficient contrast and a minimum presence of noise. | Visibility |
| The ideal amount of contrast is an optimum ___________ level. | intermediate |
| _________ is any undesirable input that interferes with the visibility of the subject of interest. | Noise |
| Scatter radiation, mottle, projection artifacts, image receptor artifacts and unwanted tissues are all examples of: | Noise |
| A ______________ is a solid white image of a subject against a darker background or vise versa. | silhouette image |
| Most radiographic images are displayed as _________ images (lighter anatomy on a dark background). | Negative |
| ______________ is defined as the range of different densities (brightness) within an image. | Gray Scale / Contrast Scale |
| ______ Scale (low contrast) presents many shades of gray | Long |
| ______ Scale (high contrast) presents only a few shades of gray | Short |
| The gray scale or contrast of an image should be adjusted using window ________. | width |
| You would adjust the overall brightness by using window ______. | level |
| The most common form of noise at the IR is ______________. | scatter radiation |
| The most common form of noise appearing in digital images is _______________. | quantum mottle |
| Image mottle is from: | Low beam penetration, low beam intensity (mAs) and/ or thick or dense anatomy |
| Background fluctuations, surges and dips in electrical current which are present in any electronic system, are classified as _________________ noise in the image. | electronic |
| __________ is all the desirable information carried by the subject contrast in the remnant x-ray beam. | Signal |
| _____________ is defined as the proportion of all useful diagnostic information to all obstructing disinformation. | SNR (Signal to Noise Ratio) |
| What are the 2 ways to improve SNR: | Reduce noise and increase signal (kVp, mAs) |
| Recognizability (Geometrical Integrity) requires: | Maximum sharpness of recorded detail, optimum magnification of the structure of interest, and minimum shape distortion of the structure of interest |
| _________________ is defined as the abruptness with which the edges of an image “stop.” | Sharpness of recorded detail |
| _____________ is a scientific term for the blurriness of image edges. | Penumbra |
| In radiography, a blurred image can result from movement during exposure of the: | x-ray tube, the patient, or the IR |
| Sharpness of detail is destroyed by: | 1. Geometric penumbra 2. Motion penumbra |
| _____________ is also referred to as size distortion and the difference between the size of a real object and the size of its projected image. | Magnification |
| What is a pathological condition in which magnification can simulate and lead to diagnostic misinformation? | cardiomegaly |
| Magnification can be done purposefully in some cases (such as in angiography) for: | an aneurism or blood clot that is too small to recognize |
| ____________ is defined as the difference between the shape of a real object and the shape of its projected image. | Shape Distortion |
| Shape Distortion consists of either: | 1. Foreshortening 2. Elongation |
| In radiography, shape distortion is caused by misalignment of the: | x-ray tube, body part, and the IR |
| ______________ is the most important component of the recognizability of an image. | Sharpness of Recorded Detail |
| ________________ is defined as the measured width of the penumbra, or the “spread of blur" and it can mathematically calculated. | Unsharpness |
| Equation to find SID: | SID = SOD + OID |
| Equation to find SOD: | SOD = SID - OID |
| Equation to find OID: | OID = SID - SOD |
| Unsharpness can be controlled by what three things? | 1. SOD (source-to-object distance) 2. OID (object-to-image receptor distance) 3. Focal spot size |
| What is the Unsharpness Formula? | (Focal spot size x OID)/SOD |
| Unsharpness is directly proportional to _______ size. | focal spot |
| Larger focal spot = _______ (smaller/larger) penumbra | larger |
| Smaller focal spot = _______ (smaller/larger) penumbra | smaller |
| What is the Percent of Magnification equation? | Image Size – object size/ Object Size x 100 |
| __________ is a shape distortion in which the length of the image in the direction of the tube angle measures longer than that of the real object. | Elongation |
| __________ is a shape distortion in which the length of the image measures shorter than that of the real object from a tilt. | Foreshortening |
| ___________ is defined as the ability to distinguish two adjacent details as being separate from each other. | Resolution |
| What are the 2 primary factors that control the degree of size distortion? | SID & OID |
| The area of uniform darkness on an image pertains to the __________. | umbra |
| Magnification can be completely eliminated within radiography by: | magnification will always inherently exists to some degree in radiographs |
| What is the equation used for the magnification of an object? | SID/SOD = Image/Object |
| What equation is used to find the factor of magnification? | SID/SOD |
Created by:
rdwilliams
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