Digital Imaging : CT test - ch. 38
the range of CT numbers of Hounsfield units varies from ___
-1,000 - +3,000
the CT console provides the radiographer access to which of the following? 1. the software program 2. table movement 3. gantry tilt
1, 2, 3
the CT radiation beam is collimated ____ 1. at the tube exit 2. at the detector entrance 3. pre-patient and post-patient
1, 2, 3
the CT table is which of the following? 1. made of carbon graphite 2. rated for maximum weight 3. motor driven
1, 2, 3
the resolution of multi-slice CT image depends on the ___ 1. pixel 2. voxel 3. matrix size
1, 2, 3
the smaller the scan field size, the ___ 1. better the resolution 2. faster the scan time 3. lesser the risk of motion
1, 2, 3
the primary mathematical method used in the creation of computerized medical images is the ___ transformation
Fourier
a series of tissue density values that evolved for CT measurements is called ___ units
Hounsfield units
chest CT studies are extremely valuable to the radiologist for a variety of reasons. the identification of a hamartoma as a benign chest neoplasm requires the verification of fat as an inner, tumor tissue component. this is accurately done with CT, through the use of what?
Hounsfield units
the ___ is how well the detectors detect the incoming photon energy
absorption efficiency
a ___ artifact is caused by attenuation of the beam as it passes through the patient
beam-hardening
the ___ is how well the detectors receive photons from the patient
capture efficiency
the ___ is determined by how well the detector utilizes the absorbed photon information
conversion efficiency
the process of modifying pixel values by a mathematical formula is called what?
convolution
first-generation CT scanners scanned the ___ only
head
the most recent generation of CT scanners use a ___ motion
helical
a helical pitch set at less than 1 permits what
improved data reconstruction due to oversampling
the CT radiographer usually varies the ___ to control the primary beam
mA
contemporary CT scanners use solid-state detectors. these detectors consist of what
rare-earth ceramic scintillators
to achieve coronal or sagittal sections in CT imaging what must occur?
reconfiguration software is implemented
the localization image produced by the CT scanner is technically called a/an
scanogram
a ___ artifact is caused by the presence of metal in the patient
star
a ___ artifact is caused by motion
streaking
computed tomography sections are acquired in the ___ plane
transverse
the gantry of the CT unit contains what?
x-ray tube