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johndc3476
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True or False:
The casette-based digital image receptor uses torage phosphor technology to create the image
- True.
- Computed radiography plates are made fo phosphors that capture the enrergy of the x-ray beam nad release the energy during the processing phase.
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A digital image is ocmposed of series of rows and columns known as matrix.
- True:
- A matrix is made up fo all pixels in a digital image arranged in rows and columns
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The brightness of a digital image is the equivalent of the term density used to describe the appearance of analog images.
- True
- The computer algorithms used to create the digital image can somewhat compenstae for underexposure or overexposure; therefore the visual cues of a dark and light images do not apply in computed radiography.
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Calcium Tungstatei sa phpspho material used for intesnifying screens.
- True:
- Calcium tungstate, non-calcium tungstate, and rare earths are the three phosphor types used in intesnifiying screens today.
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Relative speed measures the amount of exposure needed to achieve a specific optical density.
True:
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The lower the exposure level needed to achieve a specific optical density reflects an increase in the receptor speed.
- True:
- Relative speed refers to howe much exposure is needed to create an acceptable image. In order to compare screens, a measured density of 1.0 above base+fog is used.
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The silver halide component of film is suspended in a gelatin emulsion.
- True:
- Silver haldie crystasl are suspended in gelatin. This allows the processign chemicals to interact with the silver halide crystals more efficiently.
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Direct exposure radiographic film has a lower silver content than film used with intensifying screens.
False:
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The term used to describe the speed of a digital imaging system is:
Speed Class
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The ability of a digital imaging system to accurately create an output signal that matches the input signal is known as:
Detective Quantum Efficiency
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The photostimulable phosphor stores the energy deposited by the x-ray beam in the plate.
- True:
- The photostimualble phopsphor is a storage phosphor
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Flat-panel image receptors are classified as scintillator based or non-scintillator based.
- True:
- A scintilator is a device that absorbs x-ray photons and release light photons. Some flat-panel detectors use a scintilattor and some do not.
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The portion of the flat-panel detector receptor that is responsible for collecting individual electrons is the:
Thin FIlm Transistor
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The actual matrix of the flat panel detector is composed of DELs.
- True:
- Detectro elements are the portion of the TFT that collects elcetrons and produces na indiovidual pixel
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The number of electrons deposited in the DEL corresponds to the amount of radiation that strikes each area.
- True:
- Individual DELs contain charges proprotinal to the x-rays that strike each one.
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CCD is the acronym for charge-coupled device.
- True:
- The Charge-coupled device is another form of direct image capture that differs from PSP or FPD technology
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A CCD-based receptor requires the use of a scintillator material.
- True:
- The charged-couple device uses a scinitilattor to produce light photons
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A lens focuses the light produced by the scintillator onto a CCD
- True:
- The light photons released by x-rays strikign the scintillator reflect off a mirror to a lens that focuses the energy onto the CCD.
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Gas filled CT detectors have a smaller acceptance angle than scintillator based CT detectors
- True:
- Gas fillewd detrectors have smaller acceptance angles, meaning they are less sensitive to radiation than scintillator based detectors.
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CT scanners can produce images with greater contrast than many image receptors used in diagnostic imaging.
- True
- The tightly collimated x-ray beam in CT decreases scatter, which increases image contrast.
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When comparing two receptors, the receptor with the highest DQE can produce an optimal image with less radiation exposure.
- True:
- DQE is am easure of how effeiciently an image cna reproduce thei nput signnal. A high DQE means that htis iwll occur mor efficiently there for a lower dose to the patient is necessary
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Increased absorption efficiency increases the DQE of a receptor.
True
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Spatial resolution relates to the ability of an image receptor to record adjacent small objects as separate and distinct.
- True:
- When an image recpetor is able to iiamge small objects effectively, ti is said to provide increased spatial resolution
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The lp/mm is the only unit of measurement for spatial resolution.
- False:
- Spatial resolution can also be measured in cycles/mm
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Pixel size influences the spatial resolution of an image.
- True:
- The pxiel is the smallest part of a digital image. THe smalelr hte pixel is, the higher hte resolving pwoer of hte image receptor.
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