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RAD100 CH7
Vocab
| Term | Definition |
|---|---|
| Attenuation | Process by which a beam of radiation is reduced in energy when passing through tissue or other materials |
| Automatic Rescaling | Process by which images are produced with uniform brightness and contrast, regardless of the amount of exposure |
| Brightness | Function of a display monitor; changes image lightness/darkness |
| Computed Radiography (CR) | Digital image acquisition modality that uses storage phosphor plates to produce images |
| Contrast | Contrast is the difference between the ranges of adjacent IR exposures represented as gray tones in an image |
| Contrast Resolution | Ability to distinguish between very subtle differences in image receptor exposures and differentiate them from the noise in the image |
| Data Drop | Condition due to extreme overexposure, which causes digital detector elements to become overwhelmed with photon energy and leads to drop of data during image reconstruction |
| Detector Element (DEL) | Pixel-size element of the digital radiography image receptor that has a fixed dimension in x- and y-orientation |
| Detector Saturation | Data drop that involves areas or regions of the digital detector |
| Digital Radiography (DR) | Digital image acquisition systems that convert x-ray energy into a digital electronic signal for manipulation and display using direct or indirect conversion |
| Direct Conversion Flat-Panel Detector | Device that converts incident xray energy directly into an electronic signal, using a photoconductor as the xray absorber and a thin-film transistor as the signal collection area |
| Displayed Image Contrast | Relative brightness difference between the adjacent pixels in a digital image as viewed on a monitor |
| Distortion | Misrepresentation of the true size or shape of an object |
| Exposure Indicator | Numeric representation of the quantity of exposure received by a digital image receptor |
| Exposure Latitude | Range of exposures that produce a diagnostic-quality image |
| Fog | Undesirable exposure to the image receptor |
| Grayscale Bit Depth | Number of shades of gray that can be stored per detector element and displayed per pixel; ranges from 8 bits to 32 bits |
| Grid | Device consisting of thin lead strips designed to permit primary radiation to pass while absorbing scatter radiation |
| Half-Value Layer | Amount of filtration necessary to reduce the intensity of the radiation beam to one-half its original value |
| Image Receptor (IR) | Device used to capture the image for recording, such as photo-stimulable phosphor imaging plate or a digital flat-panel detector |
| Image Receptor (IR) Exposure | Amount of ionizing radiation received by the image receptor |
| Indirect Conversion Flat-Panel Detector | Device that converts x-ray energy into light; the light is then detected by a charge-coupled device or photodiodes that are coupled with thin-film transistors, and converted into an electronic signal that is sent to the computer for processing and viewing |
| Inverse Square Law | Mathematic formula that describes the relationship between radiation intensity and distance from the source of the radiation |
| Kilovoltage Peak (kVp) | Measure of the potential difference, which controls the quality and affects the quantity of x-ray photons produced in the x-ray tube |
| Latent Image | Invisible image created after exposure but before processing |
| Raw Image Contrast | Contrast recorded in the image receptor prior to computer processing. |
| Matrix | Series of picture elements (pixels) or detector elements arranged in rows and columns |
| Milliampere-Seconds (mAs) | Measurement of milliamperage multiplied by the exposure time in seconds, which controls the total quantity of x-ray photons produced in the x-ray tube |
| Penetrating Ability | Ability of an x-ray beam to pass through an object; controlled by the kilovoltage peak of the beam |
| Penumbra | Fuzzy edge of an object as imaged radiographically; also known as image unsharpness |
| Photon | Quantum or particle of radiant energy |
| Pixel | Picture element and the smallest component of the matrix |
| Primary Radiation | X-ray beam after it leaves the x-ray tube and before it reaches the object |
| Radiolucent | Permitting the passage of x-rays or other forms of radiant energy with little attenuation |
| Radiopaque | Not easily penetrable by x-rays or other forms of radiant energy |
| Remnant Radiation | Radiation resulting after the x-ray beam exits the object |
| Scatter Radiation | Radiation produced from x-ray photon interactions with matter in such a way that the resulting photons have continued in a different direction |
| Source-to-Image Receptor Distance (SID) | Distance between the source of the x-rays (usually the focal spot of the x-ray tube) and the image receptor |
| Spatial Resolution | Degree of accuracy of the structural lines actually recorded in the image |
| Subject Contrast | Range of differences in the intensity of the x-ray beam after it has been attenuated by the subject |
| Umbra | True edge of an object as imaged radiographically |
| Window Level | Digital image processing parameter that changes displayed image brightness on the monitor, usually through the use of a mouse |
| Window Width | Digital image processing parameter that changes displayed image contrast on the monitor, usually through the use of a mouse |
Created by:
hmarie94
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