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