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WorksheetsLange Physics and Instruments
Total questions: 54
Worksheet time: 27mins
Which of the following is NOT considered a degradation of the reconstruction image due to an artifact?
degrading the image quality
segmenting the voxel data
affecting the perceptibility of detain
leading to misdiagnosis
What are the two principal demands placed on an x-ray tube for CT imaging?
heat dissipation and beam filtration
high x-ray intensity and heat dissipation
high x-ray intensity and rotation speed
line focus principle and rotating anode
Which of the following photon interactions produce a photon that is deflected from its original site of interaction?
characteristic radiation
Compton interaction
Photoelectric interaction
deterministic effect
In the early days of CT scanning, reconstruction algorithms were very antiquated. What type of reconstruction algorithm was performed by Hounsfield during his first experiments?
back projection
filtered back projection
algebraic reconstruction
iterative reconstruction
Which is defined as the z-axis segmentation?
voxel
pixel
matrix
FOV
A digital image is composed of multiple pixels. What is considered a characteristic of a pixel?
cube-shaped volume of tissue that
unit of linear attenuation
two-dimensional square of data
unit of x-ray exposure in air
What is considered an electronic system for archiving, transmitting, viewing, and manipulating images in the radiology department?
DICOM
PACS
HIS
RIS
What is one of the advantages to using high kVp during CT imaging?
reduction of imaging time
reduction of reconstruction time
reduction of radiation intensity at the image receptor
reduction of radiation dose
A CTA study was performed on a patient suspected of having an abdominal aneurysm. The 3D technologist requested the voxels to be isotropic to eliminate loss of detail. Which of the following constitutes an isotropic voxel?
one in which all sides are equal
one in which the slice thickness is larger than the pixel area
one in the image needs to be reconstructed on a smaller matrix
one in the pixel size is smaller than the slice thickness
If one wants to increase the contrast resolution of an image, which of the following would be the best factor to change?
increase mAs
Increase kVp
increase beam filtration
decrease of kV
A matrix can be described by which of the following characteristics?
aperture size used during data acquisition
relationship between the FOV and pixel size
relationship between the FOV and the reconstruction algorithm
volume of tissue
Slip rings are employed in helical CT to conduct high voltage power to what components in the gantry?
x-ray tube and couch
x-ray tube and detector acquisition system
cooling and detector acquisition system
generator and the cooling system
Which of the following key performance parameters of image quality are considered indirectly proportional to each other?
spatial resolution and noise
contrast resolution and linearity
temporal resolution and contrast
spatial resolution and temporal resolution
Which of the following is the best way of reducing the partial volume averaging artifact?
faster slice acquisition
iterative reconstruction
thinner slice acquisition
increased tube output
What is a useful characteristic of a gas-filled detector for CT imaging?
no afterglow
high detector efficiency
direct digitization
DAS not required
If the u for a soft tissue is 0.215 and the u for water is 0.206, what is the correlated HU for soft tissue?
43 HU
2,000 HU
-43 HU
1,000 HU
What occurs when the interspace distance between detectors is reduced?
detector response time is reduced
patient dose is increased
signal acquisition time is increased
total detector efficiency is increased
Which of the following reconstruction algorithms is known as the convolution method?
back projection
filtered back reconstruction
algebraic reconstruction
iterative reconstruction
A CT examination of the abdomen was performed on a patient complaining of left upper abdominal pain. Upon reviewing the image, a blurring occurred at the air/fluid level of the stomach. What was the possible cause of this artifact?
beam hardening
edge gradient
motion
cone beam
What is the name given to the algorithm that compares an assumption with the measured values, makes corrections, and repeats the cycle?
analytical reconstruction
back projection
iterative reconstruction
Fourier reconstruction
What is the DFOV for a particular image having a pixel size of 0.625 mm and the matrix size of 1024?
320 mm
320 cm
640 mm2
640 mm
Of the following, what organization was responsible for the development of the DICOM standard?
ACRIN
ASRT-ARRT
ACR-NEMA
NASA
How is it possible to increase the energy of a CT examination?
raising the mAs
lowering the kVp
changing the scanned FOV
raising the kVp
Which of the following is considered the area within the gantry from which the raw data are acquired located at the isocenter of the gantry?
Display field of view
(DFOV)
reconstruction algorithm
Scan field of view
(SFOV)
detector cell size
A CT examination was performed on a patient presenting with lung cancer. The radiologist wants to determine if the disease metastasized to the patient's thoracic spine. Which of the following convolution filters would you use to retrospectively reconstruct the image for this appropriate interpretation?
bone
smooth
standard
ultra-smooth
What type of artifact is found in the pelvis running across the two femoral heads, especially when a prosthesis is present?
edge gradient
aliasing
cone beam
beam hardening
What is considered a computer visualization tool responsible for controlling the brightness and contrast of an image on the computer monitor?
3D volume rendering
multiplanar reformation
region of interest measurements
windowing
Which of the following is an important component of the Analog-Digital-Converter (ADC)?
converts continuous signal into discrete numbers
second step in image digitization
converts digital signal into analog signal
assigns an integer to the brightness value that was sampled
Which of the following reconstruction algorithms models photons and electric noise in the CT system?
filtered back projection reconstrtuction
adaptive statistical iterative reconstruction
modeled based iterative reconstruction
algebraic reconstruction
Which of the following is NOT a tenet of a good quality assurance program?
documentation
prompt interpretation
radiologist is responsible for all testing
performed on a regular basis
What technical factor determines the quantity of photons reaching the detectors?
kVp
mAs
pitch
filters
What is the most straightforward technical way to reduce or eliminate the motion of an object?
increasing speed
removing metal objects
gantry angulation
decreasing slice thickness
What generation CT scanner utilized a translate-translate scanning geometry principle with 5-30 detector linear array assembly?
first generation
second generation
third generation
fourth generation
One of the new z-interpolation process is 180-degrees linear interpolation. Which of the following is NOT an advantage of 180-degrees linear interpolation?
scanning pitches at >2
narrower slice sensitivity profile
improved z-axis resolution
reduce noise
Which of the following is NOT an advantage of cine viewing?
more accurate evaluation of structures
calculates the mean pixel values in an area
speeds up the interpretation time
increases the efficiency of the PACS system
Which of the following is the appropriate type of gas utilized gas ionization detectors?
helium
argon
xenon
neon
Which of the following forms of data is required to be preprocessed?
raw data
image data
measurement data
retrospective data
Anti-scatter grids (ASG) have been incorporated in MDCT scanners. What is the purpose of these grids?
prevent cross-talk
define slice thickness
rectify the scatter issue with an increased cone beam
define the maximum permissible beam
Which of the following allows technologist to alter the displayed picture contrast?
increasing kVp
decreasing mAs
window controls
retrospective reconstruction
A CT phantom was scanned with the results stating the CT numbers of the uniform phantom were identical throughout the phantom. What QA test was performed?
spatial resolution
low contrast resolution
linearity
cross-field uniformity
(homogeneity)
CT scanners utilize a multitude of complex computations; therefore, they employ a midrange computer. Which of the following is NOT a characteristic of a midrange computer?
networking capability
dealing efficiently with the convoluted mathematical input
fast and efficient processing
small storage capability
Which of the following is a characteristic of a homogeneous radiation beam?
all photons have the same energy
the quantity and quality of the beam changes as it passes through an absorber
all photons have different energies
known as a polychromatic beam
A CTA of the heart requires 128 detector row channels and each detector element is 0.6mm, what is the total beam collimation?
213.3 mm
76.8 cm
213.3 cm
76.8 mm
The QA test for standard deviation employs a water filled 20 cm phantom with an ROI placed in the center of the images, what is the general purpose of this QA test?
spatial resolution
noise
contrast resolution
temporal resolution
A particular CT examination requires the slice thickness to be a 5 mm and the spacing between each slice to be 5mm, what type of reconstruction interval is this considered?
overlapping interval
prospective interval
contiguous interval
gapping interval
Which of the following types of CT computer architecture requires a high structured environment that allows hardware and software to communicate, share resources, and exchange information freely?
parallel processing
serial processing
multiprocessing
distributed processing
Which of the following QA test requires the use of a Catphan phantom with inserts representing specific body densities?
spatial resolution
linearity
noise
CT number
The attenuation of a beam of radiation depends on several factors. Which of the following does NOT influence attenuation?
the atomic number of the material
the electrons per gram of tissue
the energy of the radiation beam
the acquisition geometry
What classification of image manipulation stacks the image data to generate a new series of images in a plane or orientation different from the perspective image?
prospective reconstruction
multiplanar reformation
object-based analysis
scene-based analysis
Of the following, what is considered an image display technique used to optimize image viewing by means of gray scale manipulation?
windowing
cine mode
image magnification
multiplanar reformation
A CT examination of the hip was performed with a table speed of 40 mm at a 0.5 second gantry rotation time using a 32 detector row and a 0.625 detector aperture, what is the pitch?
0.3:1
0.5:1
1:1
1.2:1
Figure Q3.1 demonstrates a fracture of the later wall of the right orbit. Which of the following windowing levels was most likely used to display the image?
- 700 HU
0 HU
+ 150 Hu
+ 600 HU
Various 3D rendering techniques are used to today to enhance diagnostic interpretation. Which of the following techniques is best utilized for the evaluation of the central tracheobronchial system?
maximum intensity projection
volume rendering
surface rendering
minimum intensity projection
What is the range of CT numbers if the window width is 450 and the window level is?
-275 to 175
275 to -175
500 to -400
-500 to 400
