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21 Cards in this Set
- Front
- Back
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When were CT systems commercially introduced for general clinical use?
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1973
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How many "generations" of CT units have been developed thus far?
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4
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What type of x-ray beam did first generation scanner produce?
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a thin, focused beam called a 'pencil beam'
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In a first generation scanner the tube and detector were part of an assembly which moved, or _____________, across the gantry while the patient remained _____________ between them.
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translated
stationary |
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The x-rays that completely penetrated the patient and were measured by a detector in series. What where these series of measurements called?
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A projection
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A first generation scanner had how many detectors?
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One single detector
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In a first generation scanner, the x-ray tube and detector would translate across the gantry to scan the patient. Then the tube/detector assembly would rotate around the patient _____________ and do another translation. This process was performed until the assembly covered a _____________ arc around the patient.
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1 degree
180 degree |
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Second generation systems incorporated an x-ray tube which generated an x-ray beam that had a shape similar to an _________________
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opened paper fan
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Second generation scanners where said to have _________________
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fan beam geometry
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Second generation scanners had multiple detectors. These detectors, together, were called the _________________
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detector array
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How many detectors made up the standard detector array of a second generation scanner?
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30
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In a second generation scanner, how did the tube/detector assembly acquire images?
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By translating across the patient
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After translating across the patient and acquiring images, how much would the tube/detector assembly rotate?
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5 degrees or more until 180 degrees had been covered
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What were the two most important features of the second generation scanner?
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Fan beam geometry
Detector Array |
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When were third-generation scanners first introduced?
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1975
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What is the difference between 2nd and 3rd generation scanners in relation to detectors?
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2nd gen features a straight detector while 3rd gen features a curved arc detector.
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What type of beam do 3rd gen scanners use?
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A fan beam
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What kind of motion does the 3rd gen scanner's tube/detector assembly use to acquire images?
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the assembly rotates around the patient
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3rd gen scanners allowed total scan times faster than _________________ per image.
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1 second
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What type of tube/detector assembly do the 4th gen scanners use?
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A stationary detector ring that lines the gantry. The ring can angle itself but only the tube rotates around the patient
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What type of beam do 4th gen scanners use?
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A fan beam
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