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7 Cards in this Set
- Front
- Back
Processes involved at the cathode |
1. Tungsten filament is heated 2. Causes excitation in the tungsten particles 3. Electrons leave the tungsten atoms 4. Form a space around the cathode 5. Potential difference (voltage) applied 6. Electrons accelerated toward the anode 7. Slowed down of stopped within the anode target 8. Produces heat and x rays |
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Computed Radiography |
CR uses an imaging plate to capture an image The plate is made of a storage phosphor that captures xray energy When scanned with a laser the plate emits light This is captured by the plate reader in order to build up and image from measurements made on the released energy Storage phosphors capture a wide range of exposures They produce a signal directly proportional to the energy they have stored |
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Computed Radiography 2 |
Film systems are sensitive to only a narrow range of exposures This means that a high-quality image can be produced regardless of the relative amount of exposure of the plate Can produce a good quality image with poorer exposures than film Uses cassettes but not film - provide a digital image Cheaper than DR - usually the first alternative in converting from film to digital imaging Can be used portably |
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Digital radiography |
No screens Charged coupling device (CCD) or amorphous selenium plate Xray energy is converted directly into electrical energy The image is shown almost immediately on the monitor - real time Straight from image to capture to digital image on the monitor display Faster so more patient throughput- but more expensive |
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Image display |
When an image has been processed into a digital form it can be: -displayed on a monitor -printed on film -sent to a distant location -stored on a disc Laser camera printing - computed images can be altered while viewing a monitor and then printed on to a film by a laser camera Multiple images can be copied on to a single sheet and multiple copies can be printed of a single images |
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Contrast enhancement |
Alteration of pixel values to display different brightness levels Higher pixel - better detail Aim is to improve diagnostic accuracy Poor contrast = missed diagnosis |
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PACS |
Picture archiving and communication system Provides: Capture Storage Display of medical images Distribution |