CT Exam 2 Questions with answers

CT Exam 2 Questions with answers
The first operation to which raw data is subjected is referred to as
A. Convolution
B. back-projection
C. 3-D surface shading
D. none of the above - VERIFIED ANSWER✔✔-A. convolution

The basic problem of the back-projection algorithm is?
A. classical star pattern in the image
B. image is blurred
C. image is not diagnostic
D. All the above - VERIFIED ANSWER✔✔-D. All the above

Which algorithm is also known as the 'summation method'? - VERIFIED ANSWER✔✔-Back projection

Which of the following belongs to the class of analytical algorithms for computed tomography?
I. back projection
II. filtered back projection
III. Fourier reconstruction - VERIFIED ANSWER✔✔-2 and 3

Raw data in CT is:

A. data from the detectors
B. requires a vast amount of hard disk space
C. subject to the image reconstruction process
D. all the above - VERIFIED ANSWER✔✔-all the above

The mathematical manipulations required during the reconstruction of a CT image are accomplished using a(n):

1. algorithm
2. kernel
3. mathematical filter function - VERIFIED ANSWER✔✔-all 3

____________ data is the reconstructed data that has been projected back onto a matrix after convolution by an
algorithm and displayed on a monitor as a gray scale CT image.

A. matrix
B. raw
C. image - VERIFIED ANSWER✔✔-image

A CT image is formed in part by projecting back all of the attenuation values recorded during data acquisition
onto a:

pixel
voxel
matrix
detector - VERIFIED ANSWER✔✔-matrix

Which of the following algorithms is most commonly used in state of the art computed tomography scanners?

iterative algorithms
back projections
filtered back projection

, fourier reconstruction - VERIFIED ANSWER✔✔-filtered back projection

Image data are obtained: - VERIFIED ANSWER✔✔-after back projection

Which describes the beam that diverges from the x-ray tube to the outer edges of the detectors? - VERIFIED
ANSWER✔✔-cone beam

_________________ is a mathematical filtration used by the CT system to remove blurring artifact during the
back projection method of image reconstruction. - VERIFIED ANSWER✔✔-convolution

A smoothing filter accentuates the difference between the neighboring pixels to enhance spatial resolution.

T or F - VERIFIED ANSWER✔✔-False

What does an edge filter do? - VERIFIED ANSWER✔✔-accentuates the difference between neighboring pixels
to enhance spatial resolution.

Convolution kernels can be applied only to raw data.

T or F - VERIFIED ANSWER✔✔-True

The new generation of multislice computed tomography scanners requires modified image reconstruction
algorithms.

T or F - VERIFIED ANSWER✔✔-True

Uses data to later generate a new image - VERIFIED ANSWER✔✔-Retrospective Reconstruction

Process of using raw data to create an image is called image reconstruction. This construction is automatically
produced - VERIFIED ANSWER✔✔-prospective reconstruction

During quantization, the value of the integer is determined by

size of patient
FOV
matrix size
attenuation values - VERIFIED ANSWER✔✔-attenuation values

Each pixel in a digital image will be assigned one of these. (3) - VERIFIED ANSWER✔✔-integer, CT number,
shade of grey

Higher CT numbers are usually assigned what color

black
white
grey - VERIFIED ANSWER✔✔-white

also called reconstructed data, are convolved data that have been projected into the image matrix to create CT -
VERIFIED ANSWER✔✔-image data

this data is the result of preprocessed scan data and are subjected to the image reconstruction algorithm used by
the scanner - VERIFIED ANSWER✔✔-raw data

this data is subject to convolution to correct the blur artifact from the back projection reconstruction process -
VERIFIED ANSWER✔✔-filtered or convolved data

A common operation in this processing technique is Fourier domain processing - VERIFIED ANSWER✔✔-
global operations