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Radiology
Chapter 4 Vocab
| Term | Definition |
|---|---|
| Contrast | The visual differences between shades ranging from black to white in adjacent areas of the radiograph. A radiograph that shows few shades has a short scale or high contrast. Many variations in shade has a long scale or low contrast. |
| Crystal | Refers to the silver halide combinations that are present in the film emulsions. Larger crystals require less radiation exposure to produce an image. |
| Definition | Sharpness and clarity of the outline of the structures in a radiographic image. Poor definition is generally cause by a movement of the patient, image receptor, or the tube head during exposure. |
| Density | The overall darkening or blackening of the radiographic image. Increasing or decreasing the milliamperage and exposure time affects density. |
| Exposure Time | The time interval expressed in seconds or impulses that x-rays are produced. |
| Intensifying Screen | Plastic sheet coated with calcium tungstate. When exposed to radiation, the fluorescent salts glow, giving off a blue or green light. Produces a latent image faster than is possible when radiation is used alone. |
| Inverse Square Law | States that the intensity of radiation is inversly proportional to the square of the distance from the source of the radiation to the point of measurement. |
| Long Scale Contrast | Low contrast image. A radiographic image with many shades of gray. Produced with high kilovoltage. |
| Object Film Distance | Distance between the object being recorded and the image receptor. |
| Penumbra | Partial shadow or fuzzy outline around the image. |
| Radiolucent | The portion of the radiograph that is dark structures that lack density permit the passage of x-rays with little or no resistance. |
| Radiopaque | Portion of the radiograph that appears light. Resist the passage of radiation |
| Shortscale Contrast | High contrast image. Radiograph exhibits black and white with few shades. Produced with low kilovoltage. |
| Target Film Distance | Distance between the focal spot on the target and the recording plane of the image receptor. |
| Target Object Distance | Distance between focal spot and object being radiographed. |
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