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CCD/CMOS Image Capture chapter 3,6,9 questions well answered graded A+
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CCD/CMOS Image Capture chapter 3,6,9 questions well answered graded A+
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CCD/CMOS Image Capture chapter 3,6,9A scintillator converts x-rays into - correct answer ✔✔visible light.
Gadolinium oxysulfide - correct answer ✔✔unstructured
Cesium iodide - correct answer ✔✔structured
Light is then converted into an electrical charge by - correct answer ✔✔CCD or CMOS devices, or
photodetectors such as amorphous silicon photodiode arrays (last chapter)
Charge-Coupled Devices CCDs - correct answer ✔✔The oldest indirect-conversion DR system
X-ray photons interact with a scintillation material and this signal is coupled or linked by lenses or fiber
optics, which act like. - correct answer ✔✔cameras
These "cameras" - correct answer ✔✔reduce the size of the projected visible light image and transfer
the image to one or more small (2 to 4 cm2) CCDs, which convert the light into an electrical charge.
The electrical change are stored - correct answer ✔✔in a sequential pattern and released line by line
and sent to an analog-to-digital converter.
CCD Sensor - correct answer ✔✔Example: Fluoroscopic Detector
CCD-based detectors require - correct answer ✔✔optical coupling and image size reduction, they are
widely available and relatively low in cost.
A CCD is made up of - correct answer ✔✔photosensitive receptor and electronics embedded in a
substrate material in a silicon chip.
•Incident light from a scintillator strikes the detector, and electron-hole pairs are produced in the silicon.
, The amount of electron-hole pairs is related to the - correct answer ✔✔amount of light absorbed.
The electrons inside the CCD are held - correct answer ✔✔by electrostatic forces in the array until the
charge is read out to form the image
The detector element (del) contains three electrodes that hold the electrons in an electrical potential
well - correct answer ✔✔The dels are formed by voltage gates that , at readout, are opened and closed
like gates to allow the flow of electrons.
To collect the charge on the silicon chips, the voltage sign is changed on the electrodes within each del,
moving the electrons by rows down the columns until the readout row is reached.
This is commonly known as the bucket brigade scheme.
It is not practical to manufacture a CCD chip larger than - correct answer ✔✔5 cm x 5 cm.
Most range from 2 to 4 cm
The image must be matched to the size of the CCD.
CCD technology uses lenses or fiberoptics so that the image matches the receptor size
Reducing the image size involves several components that contribute to the quality of the image -
correct answer ✔✔The scintillator
Light collection component
Noise
The scintillator and the way it is constructed will determine: - correct answer ✔✔How many of the
incident x-ray photons are absorbed
How much light is produced
The wavelength or color of the light
The optics in a CCD are critical contributors to the - correct answer ✔✔quality of the digital image.
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