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PRI 2 Unit 3 Terms
SJC PRI 2 Unit 3 Willis
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____ ___ Location on a digital image number scale at which the levels of grays are assigned. It regulates the optical density of the displayed image and identifies the type of tissue to be imaged. | Window Level |
_____is the amount of luminance (light emission) of a display monitor. | Brightness |
____ ___ is the ability of the image receptor to distinguish between objects having similar subject contrast. | Contrast Resolution |
____ ____ refers to the range of exposure intensities an image receptor can accurately detect. | Dynamic range |
_____ ____ is a numeric value that is displayed on the processed image to indicate the level of x-ray exposure received to the digital image receptor. | Exposure Index |
_____ ____ Measure of resolution; usually expressed in line pairs per millimeter (lp/mm). | Spatial Frequency |
_____ ____ is the amount and energy of the x-rays reaching an area of the image receptor. | Exposure Intensity |
___The number of different shades of gray that can be stored and displayed by a computer system. | Greyscale |
____ ____ how often the analog signal is reproduced in its discrete digitized form. | Sampling Frequency |
___ _____ Specific number of gray levels or digital image numbers assigned to an image. It determines the gray scale rendition of the imaged tissue and therefore the image contrast. | Window Width (contrast) |
____ ___ Ability to image small objects that have high subject contrast. | Spatial Resolution |
A __is a graphic representation of a data set. The x-axis represents the _____ of exposure, and the y-axis represents the ___ of pixels for each exposure level. | Histogram; amount; incidence (number) |
The computer analyzes the histogram using processing algorithms and compares it with a pre-established histogram specific to the anatomic part being imaged. This process is called _____ ___ | Histogram Analysis |
____ determines the range of the histogram data set included in the displayed image. | Values of interest |
Histogram analysis is also employed to maintain consistent image ___despite overexposure or underexposure of the IR. This procedure is known _____ ____. | Brightness; automatic rescaling |
____ _____ Occurs during histogram analysis and is employed to maintain consistent image brightness despite overexposure or underexposure of the digital image receptor. | automatic rescaling |
The _____ _____ provides a numeric value indicating the level of radiation exposure to the digital IR. | Exposure Indicator |
The ____ image is stored as digital data and must be processed by the computer for viewing on a display monitor. | latent |
Matrix: combination of ____ and ___ | rows; columns |
____: "picture elements" or smallest component of matrix. | Pixels |
(pixel) Recorded as a single numerical value representing a ___ level on a display monitor. | brightness |
(pixel) Location in the matrix corresponds to a/an ____ within the patient or ____ | area; volume |
Digital image quality is improved with a larger matrix size that includes a ___ number of ___ pixels. | greater; smaller |
Larger matrix results in: Computer processing time will___ (increase/increase) | increase |
Numerical value assigned to a pixel is determined by the relative ___ of x-rays passing through the volume of tissue. | attenuation |
_____ or number of bits (2n) determines the number of shades of gray that can be displayed. | pixel bit depth |
The____ the number of pixels in an image matrix, the smaller their size. | greater |
Pixel ____: number of pixels per unit area. Decreasing this will ____ (increase/increase) spatial resolution. | density; decrease |
_____ ____: distance measured from the center of a pixel to an adjacent pixel. Increasing this will ___ (increase/increase) spatial resolution. | pixel pitch; decrease |
Spatial resolution is limited to the __ of the pixel. | size |
An image composed of ___ sized pixels has improved spatial resolution. | smaller |
Spatial frequency is defined by the ___. | unit of line pairs per milimeter -lp/mm |
Small objects have ____ (higher/lower) spatial frequency and large objects have ____ (higher/lower) spatial frequency. | higher; lower |
___ the number of ____ resolved in the imaging system results in improved spatial resolution. | increasing; lp/mm |
A ____relationship exists between window level and image brightness on the display monitor. Increasing the window level ___ the image brightness; decreasing the window level ___the image brightness. | direct; increasing, decreasing -indirect relationship to pixel value (low = white, high = dark) move the window level towards the pixel value you want to see better!) |
____ ___provide the means to alter the original pixel values to improve the brightness and contrast of the image. | lookup tables |
With digital, the computer creates a __ of the data set, a graph of the exposure to the ___ elements and the prevalence of the exposures within the image. it is compared with a stored histogram model for the part; VOIs are identified - image is displayed. | histogram; pixel |
A narrow (decreased) window width displays ___ radiographic contrast, whereas a wider (increased) window width displays ____ radiographic contrast. | high; low |
____is a technique that can remove superimposed structures so that the anatomic area of interest is more visible. | subtraction |
_ is a post processing technique that alters the pixel values to increase image contrast. | contrast enhancement |
___ ___ is a post processing technique that improves the visibility of small, high-contrast structures. __ __ may be slightly increased. | edge enhancement; image noise |
___ is a post processing technique that reverses the grayscale from the original radiograph. | inversion |
__is a post processing technique that suppresses image noise (quantum noise). __ is degraded. | smoothing; spatial resolution |
_____ is a computer system designed for digital imaging that can receive, store, distribute, and display digital images;____ and____ are computer systems that provide medical information. | PACS-picture archival&communication systems; RIS-radiology information systems; HIS-hospital information systems |
____is a communication standard for information sharing between PACS and imaging modalities. | DICOM- digital Imaging and communications in medicine |
____ is a communication standard for medical information. | HL7- Health Level Seven Standard |