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18 Cards in this Set
- Front
- Back
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Diagnostic Radiology Imaging Method
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conventional radiography (plane film); cross-sectional imagining techniques (more expensive than radiation); nuclear radiation ( inject radial isotope to see different functions in body)
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Conventional radiography
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film radiography
computed radiography (CR) digital radiography (DR) fluoroscopy |
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Film Radiography
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utilizes a screen-film system within a film cassette as the x-ray detector
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Computed Radiography
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filmless system eliminates chemical processing during digital radiographic images; CR substitue a phosphor imaging plate for the film screen cassette; digital images transferred to picture archiving and communication system (PACS)
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Digital Radiography
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film free and cassette free; DR substitutes a fixed electronic detector-direct read out produce immediate DR image
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fluoroscopy
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a continuous x-ray beam passes through patient onto a fluorescing screen; provides real time radiographic visualization of moving anatomic structures
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cross-sectional imaging technique (CT, MR, US)
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produce cross-sectional images; all interrogated a 3-D volume or slice of tissue to produce a 2-D image; US- fairly cheap, no ionizing radiation; CT- need big computer to reconstruct images; don't want to CT babies; it's fast, gives a lot of info, but also a lot of radiation
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computed tomography
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uses a computer to reconstruct mathematically a cross-sectional image of the body from measurement of x-ray transmission through thin slices of patient tissue; evaluates only a single tissue parameter - x-ray attenuation
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Computed tomography: How is x-ray beam attenuated?
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by absorption and scatter as it passes through patient
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Computed tomography: What are CT pixel numbers proportional to?
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difference in average x-ray attenuation of tissue within voxel and that of water
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hounsfield unit
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measurement of the density of how things are in a CT
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How many hounsfield units are there for the following: bone, soft tissue, fat, lung tissue, air and water
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bone: 400 to 1000H
soft tissue: 40 to 80H fat: -60 to -100H lung tissue: -400 to -600H air: -1000H water: 0 H |
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For Magnetic Resonance Imaging, what tissue characteristics does it analyze?
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hydrogen or proton density; T1 (fat) and T2 (water weighted) relaxation times of tissue; blood flow within tissue
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advantages and limitations of MR
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advantages: excellent soft tissue resolution, provide images in any anatomical plane, absence of ionizing radiation; limitations - limited ability to demonstrate dense bone detail or calcifications
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ultrasonography
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composite US images are produced by interrogating tissue in field of view with multiple closely spaced pulses; real-time images of moving patient tissue; cheap
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US artifacts
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acoustic shadowing- means it has hit a solid object
acoustic enhancement- has hit water and becomes brighter |
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nuclear radiology
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nuclear medicine images reflect not only biodistribution of the radiopharmaceutical but also the anatomic, pathologic and artifact overlays present at time of imaging;
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nuclear radiology: pet imaging
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uses beta particle attached to glucose - look for metabolic activity in body (cancers use a ton of glucose)
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