DR System

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by drsystem
Last updated 4 years ago

Discipline:
Science
Subject:
Health & Medicine

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DR System

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(NOTE: digital radiography is more efficient in time, space, and personnel than screen-film radiography.)

Capture, Coupling, Collection

By: Samar Jeffrey, Amanda Mackler, Beth Stewart, & Michaela Thess

DR System

1: Capture Element

How x-rays are captured.While CR uses a photostimulable phosphor...INDIRECT CAPTURE: x-ray → light → electric signalUses a scintillation phosphor to convert x-rays to light, either Gadolinium Oxysulfide (GdOS) or Cesium Iodide (CsI).DIRECT CAPTURE: x-ray → electric signal Because x-rays are converted directly into an electric signal, there is no scintillation phosphor. Instead it uses a photoconductor, Amorphous Selenium (a-Se).

2: Coupling Element

Produces the electronic signal, transferring the x-ray signal to the collection element.INDIRECT CAPTURE USES:Fiberoptic bundles.Contact layer.DIRECT CAPTURE USES:Again, Amorphous Selenium (a-Se). Doubles as both the capture and the coupling element in direct capture.

3: Collection Element

Gathers the signal to be further processed. Charge-Coupled Device (CCD): light-sensitive device that collects light photons; or, a solid state system that converts light photons into an electric signal/electrons with a very high spatial resolution. Advantages: - High sensitivity to light. - Wide dynamic range. - Small size of 1-2 cm (with a pixel size of 100x100 μm) equals better spatial resolution. - Better contrast resolution. - Ergo, better radiation protection.Thin-Film Transistor (TFT): charge-sensitive device that collects electrons.INDIRECT CAPTURE USES: When the coupling element is fiberoptic, Charge-Coupled Device (CCD). When contact layer, Thin-Film Transistor (TFT). DIRECT CAPTURE USES: Thin-Film Transistor (TFT).

FILL FACTOR: the percentage of the pixel face that is sensitive to the x-rays/occupied by the sensitive image receptor. 80% = fill factor. 20% = does not contribute to image.SPATIAL RESOLUTION: ability to produce very small high density objects visible on the image.

Don't forget:

includes 3 elements

CREATED in the 1970s

cuts out the middle man

CCD

like a BRIDGE


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