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31 Cards in this Set
- Front
- Back
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•tomography
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greek tomos = section
a conventional tomogram is an image of a section of the pt that is oriented parallel to tee film |
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•transverse axial tomography
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aka tomography
1937 Watson tomographic technique in which the sections were transverse sections lacked enough digital clarity t be used diagnostically |
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•transmission CT
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radiation source was from outside the pt
opposite of emission CT in which the radiation came from within the pt (ex nuclear medicine) |
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•data acquisition
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collection of the x-ray transmission measurements from the patient
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•scanning
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translate-rotate-stop- rotate
repeated over 180 degrees |
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•image reconstruction
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after enough transmission measurements have been collected by the detectors, they are sent to the computer for processing
comp uses special mathematical techniques to reconstruct the CT image through image reconstruction algorithms |
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•optical/laser storage
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the stored data are read by optical means such as a laser beam
includes disk, tape, and card |
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•gantry
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•Hounsfield
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1971 - first prototype brain scanner
1972 - first patient was scanned CT = computerized tomography inventor of computed tomography shared Nobel prize with Allan Cormack |
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•EMI
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Electric and Musical Industries
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•Cormack
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shared Nobel prize with Godfrey Hounsfield for his mathematical contributions to the problem in CT
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•americium
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radiation source
homogenous beam 9 days to acquire data 2.5 hours to reconstruct |
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•Ledley
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Robert developed first whole body CT scanner
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•generation
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term used to refer method of scanning
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•high speed CT
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Dynamic special reconstructor (DSR)
to carry out dynamic volume scanning to accommodate imaging of the dynamics of organ systems and functional aspects of cardiovascular and pulmonary systems with high temporal resolution as well as imaging anatomic details |
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•dose descriptors
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include the single scan profile, multiple-scan profile, CT dose index, multiple-scan average dose, and isodose curves
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•quality control
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many tests available
techs can perform some and some need expertise some use phantoms provided from the manufacturer ACR phantoms (consists of 4 sections which can be imaged simultaneously to generate several test results |
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•digital imaging system
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•ADC
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analog to digital converter
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•DAC
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digital to analog converter
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•rendering
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process of reconstruction
surface rendering and volume rendering |
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•volume CT
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patient moving continuously through gantry while the tube and detectors rotate continuously for several rotations
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•spiral/helical CT/single slice and multi slice
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spiral/helical = patient moving continuously through gantry while the tube and detectors rotate continuously for several rotations
single slice = patient scanned one slice at a time. the tube and detectors rotates 360 degrees or less to scan one slice while the table and patient remains stationary |
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•applications of volume CT scanning
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CT fluoroscopy
CT angiography 3D imaging and visualization cardiac CT imaging |
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•CT fluoroscopy
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continuous imaging
allows for reconstruction in live time based on 3 advances in CT: 1 fast continuous scanning - spiral/helical 2 fast image reconstruction 3 continuous image display |
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•3D imaging and visualization
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hardware or software based approach
can make 3D image from ct slice info |
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•CT angiography
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CT imaging of blood vessels opacified by contrast media
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•cardiac CT imaging
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to image the beating heart with a goal of reducing motion artifacts and a loss of both special and contrast resolution
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•CT screening
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a means to screen for early disease
due to excellent image quality and speed of current CT scanners |
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image formation
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data acquisition
image reconstruction image display, manipulation, storage, recording and communication |
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isotropic voxels vs. anisotropic voxels
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isotropic = perfect cubes with all dimensions being equal
anisotropic = dimensions are not equal/ not perfect cubes |
