Image processing

Question 1

The mathematical filtration of CT data to enhance the appearance of specific tissue types is called

Answer 1

Convolution

This is what the computer system uses to enhance the appearance of certain tissues.

Question 2

Compared to a 1.25 mm image, 3.75 mm data will demonstrate:

Answer 2

1. Decreased image noise

2. Fewer total slices

Question 3

Which of these image-processing technique in CT are only used in helical scanning?

Answer 3

Interpolation

Question 4

The process of assigning a specific level of edge-enhancement to the CT image data is controlled by mathematical filters called:

Answer 4

1. reconstruction algorithms
   2, reconstruction filters
2. reconstruction kernels

Question 5

The process of reconstruction in the CT computer system creates:

Answer 5

Image data

Question 6

if the construction slice thickness is set to 3.0 mm.

Answer 6

The image data is 3.0 mm thick

Question 7

What mathematical process prevents star-like artifacts from appearing on the CT images?

Answer 7

Back-projection filter

Question 8

A region of interest (ROI) indicating an average Hounsfield unit (HU) of +39 mostly likely corresponds

Answer 8

Blood

Question 9

Using a larger reconstruction slice thickness results

Answer 9

1. Decreased image noise

2. Decreased spatial resolution

Question 10

In the reconstructed image data, the distance from the start of one slice to the start of the next slice is defined as the:

Answer 10

Slice interval

Question 11

Iterative reconstruction is an alternative to traditional reconstruction and helps to

Answer 11

1. Reduce patient dose
2. Increase image quality

A complex process.

Question 12

Which of there scenarios will result in gaps in the reconstructed image information?

Answer 12

When the slice interval is greater than the slice thickness

Question 13

Which three of these scan parameters can be changed retrospectively

Answer 13

1. Scan start and end locations
2. Slice thickness
3. Display field of view (DFOV)

Question 14

During a routine CT scan of a pediatric chest, the radiologist requests that the technologist reconstruct the image data with 1.25 mm slices rather than 2.5 mm slices. One negative effect of this change will be:

Answer 14

Increased image noise

Question 15

What two combinations of reconstruction parameters could be used to create detailed images of the bony trabeculae?

Answer 15

1. Thin slices

2. Edge-enchaining algorithms

Question 16

A patient in the emergency department is suspected of having a blowout fracture of the right maxillary sinus. Structural damage to the soft tissue of the eye will be best demonstrated with which of these filters?

Answer 16

Smooth algorithms

Question 17

Which of these Ct protocol generally use thin slices?

Answer 17

Circle of Wills for arterial-venous malformation

Question 18

Thicker slices are suitable for

Answer 18

1. Abdominal imaging

2. Thoracic imaging

Question 19

After performing an abdominal scan for trauma, the radiologist requests reconstructed images of the lumbar spine. The raw data is not saved on the Ct scanner, so this will require:

Answer 19

Rescanning the patient

Retrospective reconstruction can never be done without raw data on the CT scanner. If the raw data is gone, there absolutely no way to reconstruct new images.

Question 20

By definition, the acquisition thickness is the same as the:

Answer 20

Detector row thickness

Question 21

Which of the following accurately describes where raw CT data is stored?

Answer 21

In the CT computer system

Question 22

A region of interest (ROI)placed over an abnormal lesion yields an average CT number of -52. This lesion may be composed of:

Answer 22

Fat

Question 23

Which two algorithms are most useful for viewing soft tissue changes around the cranium?

Answer 23

1. Smoothing algorithms

2. Standard algorithms

Question 24

After performing a thoracic spine scan for trauma, the radiologist requests images of the entire bony thorax. The raw data is still saved on the CT scanner. This will require:

Answer 24

Retrospectively reconstructing images with a different display field of view (DFOV)

Question 25

Estimating an unknown values in a series of known values is a mathematical process called:

Answer 25

interpolation

This is what allows the spiral-shaped raw data to be converted into axial image data

Question 26

Which two of those algorithms are preferred for viewing bone?

Answer 26

1. Edge-enchaining algorithms

2. Bone algorithms

Question 27

Thick reconstruction slices (greater than 3 mm) are not suitable for

Answer 27

1. multiplanar reformations
2. Angiographic imaging

Thick slices should never used for multiplanar reformations as this results in blurriness in the images.

Thick slices should also never used for protocols requiring high spatial resolution, such as angiography imaging.