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Radiology
Chapter 7 Vocab
| Question | Answer |
|---|---|
| Distortion | The difference between the actual subject and its radiographic image. |
| Umbra | The portion of the image that is common to all points on the focal spot. |
| Penumbra | The term used to describe the "unsharp edges" of the umbra, or body part. |
| Source-image receptor distance (SID) | The distance between the tube-target and the film or imaging plane. |
| Inverse Square Law | Radiation intensity is inversely proportional to the square of the distance. |
| Underexposed | A film that is too light. |
| Overexposed | A film that is too dark. |
| Tissue density | The mass density of the radiographic subject that causes a lighter area on the radiograph because of greater absorption in some body parts. |
| Film/screen contact | that property of the cassette that keeps the film in uniform tight contact with the two intensifying screens. |
| Contrast | The difference in radiographic density between adjacent portions of the image. |
| Short scale contrast | High level contrast produced by low kilovoltage. Approximately 5 gray tones. |
| Long scale contrast | Low level contrast produced by high kilovoltage. Approximately 15 gray tones. |
| Subject contrast | Radiographic contrast influenced by the tissue densities within the subject. |
| Latitude | Long scale contrast. |
| Fog | Unwanted exposure on the film that causes all parts of the image to appear as though seen through a gray veil. |
| Magnification | That property of distortion wherein the image is larger than the object. |
| Object-image receptor distance (OID) | The distance between the subject and the film. |
| Quantum Mottle | The uneven distribution of photons within the x-ray beam. |
| Density | The overall blackness or darkness of the radiograph. |
| Elongation | A form of shape distortion where the projected part appears longer than it really is. |
| Foreshortening | A form of shape distortion where the projected part appears shorter than it really is. |
| Penetrometer | A solid piece of aluminum with steps of varying thickness. Often referred to as a step-wedge. |
| Radiographic Contrast | The overall contrast seen in a radiographic image. It is a product of the IR (film) contrast and the subject (patient) contrast. |
| Recorded Detail | The sharpness of the structures in the image. Also called detail, sharpness, and resolution. |
| Shape Distortion | The result of unequal magnification of the actual shape of a structure. Displaces the projected image of an object from its actual position. |
| Size Distortion | Distortion that is always in the form of magnification enlargement. |
| Voluntary Motion | A normally controllable motion. |
| Involuntary Motion | Movement over which the patient has no control, such as tremors, peristalsis, and heartbeats. |
Created by:
hollieritter
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