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ch26 Dig Fluoro

Equipment. Chapter 26. Digital Fluoroscopy

QuestionAnswer
Pixel size = image intensifier size/ matrix
The difference between conventional and DF is the nature of the image and the manner in which it is digitized
a 1024x1024 image matrix is sometimes described as a ____ line system 1000.
spatial resolution is limited by pixel size
In DF the spatial resolution is determined both by image matrix size, size of image intensifier. (limited by pixel size)
Tube current is measured in ______________ instead of less than 5 mA, as in ii fluoro. hundreds of mA
Images from DF are obtained by pulsing the x-ray beam in a manner called pulse progressive fluoro.
During DF, the x-ray tube operates in the ______ mode radiographic
The time required for the tube to be switched on and reach selected levels of kVp and mA is called the interrogation time.
The time required for the tube to be switched off is the extinction time
The fraction of time that the tube is energized is called the duty cycle
For DF, what two types of image receptors are there? CCD, Flat panel
CCD in Digital is used instead of _______ in conventional. a TV camera tube
What is an image intensifier? Electronic vacuum tube that amplifies a fluoroscopic image to reduce patient dose
When the CCD is directly coupled to the image intensifier, the entire CCD signal is sampled and drives the _____ system ABC
______ has greater sensitivity to light (DQE), and a lower level of noise than a television camera. The results are a higher ____ and better ________. CCD. Higher SNR, better contrast res. (results in lower pt dose)
Advantages of CCD? High spatial res, high SNR, high DQE, no warm up required, no lag or blooming, no distortion, no maintenance, unlimited life, linear response, lower pt dose.
Perhaps the single most important feature of CCD? linear response to light
Advantages of Flat panel image receptors over CCD image intensifiers? Distortion free images, improved contrast resolution, High DQE, rectangular image area coupled to similar image monitor, unaffected by external mag fields. (also smaller, lighter, manipulated easier)
Image intensifiers are limited by nonuniform spatial res and contrast res from the center to the periphery of the circular image. _____ and ______ increase with age. FPIR is uniform and doesnt degrade. Veiling glare and pin cushion
The DF IR has two alternatives, ________ and _________. So does the display.... _____ and ______. CCD and Flat panel. Video and flat panel
In DF the TV camera tube reads in ___________ mode. progressive
Important characteristics of a DF system that are computer controlled include image _________ ________, the system ______ _______, and the image _______ ______. matrix size, dynamic range, acquisition rate
The principle advantages of DF examinations are the image ____ ____ that are possible, and the enhanced visualization of vasculature that results from venous contrast. subtraction techniques
________ subtraction techniques are used most frequently because of high voltage generator limitations associated with the ______ subtraction mode. temporal, energy
________ subtraction refers to an image obtained at one time is subtracted from an image obtained at a later time. If during the intervening period, contrast was introduced, what would the subtracted image look like? temporal. Subtracted image would contain only the vessels filled with contrast.
Two methods commonly used of temporal subtracting? mask mode and time interval difference (TID) mode.
method of temporal subtraction that results in successive subtraction images of contrast filled vessels? mask mode
Technique that produces subtracted images from progressive masks and the frames that follow? Time interval difference mode (TID) (method of temporal subtraction..) {{Each subtracted image is made from a difference mask and follow up frame}}
If patient motion occurs between the mask image and a subsequent image, the subtracted image will contain ___________ artifacts. misregistration
A single kVp setting is used? Rapid kVp switching is required? temporal, energy
filter switching is preferred? Normal beam filtration is ok? energy, temporal
Higher x-ray intensity is required for comparable contrast resolution? Contrast Res is 1mm at 1%. energy, temporal
Imply image subtraction? Complex image subtraction? temporal, energy
Motion artifacts are a problem? Motion artifacts are greatly reduced? temporal, energy
Total subtraction of common structures is achieved? Some residual bone may survive subtraction? temporal, energy
Many more types of subtraction images are possible? Subtraction possibilities are limited by the # of images? energy, temporal.
What is hybrid subtraction? combing temporal and energy subtraction techniques
What is subtraction? removing or masking all unnecessary anatomy from an image and enhancing only the anatomy of interest
Created by: Zoest35