Data Acquisition

Question 1

Shifting the center of a sagittal image requires changes to which two data coordinates?

Answer 1

1. Y-axis

2. Z-axis

Question 2

Pitch is defined as the ratio of the table movement to the

Answer 2

Beam width

When the table movement per tube rotation is the same as the beam width, the pitch is equal to 1.

Question 3

What CT data acquisition mode collects a series of adjacent axial sections

Answer 3

Axial scanning

Question 4

If the pitch is equal to 1.1, how far is the patient table moving during rotation of the tube

Answer 4

1.1 times the beam width

Question 5

A CT detector configuration is changed from 0.625 mm x 16 rows to 1.125 mm x 8 rows. The change may result in:

Answer 5

Decreased patient dose

Thinker detector rows require less radiation to produce a quality signal, which allows for a decrease in patient dose. This change will actually decrease the spatial resolution, but the total scan time and beam coverage will stay the same.

Question 6

During an axial scan, the total amount of anatomical coverage per tube rotation is dependent on which of the following two variables?

Answer 6

1. Number of activate detector rows

2. Thickness of activated detector rows

Question 7

During helical scanning, if the table moves a greater distance than the width of the beam the pitch will be

Answer 7

Greater than 1

Question 8

When imaging a patient in computed tomography, what portion of the patient is processed for viewing on the technologist’s computer monitor?

Answer 8

Any part of the patient within the display field of view (DFOV)

Question 9

Which of the following statement accurately describes the orientation of the Z-axis in CT imaging?

Answer 9

1. Extends longitudinally through the scanner

2. Represents data coordinates in terms of superior and inferior

Question 10

What two CT scanning modes activate the x ray tube only while the patient table is stationary?

Answer 10

1. Axial scanning

2. Volume scanning

Question 11

If routine helical scan of the chest is pre-programmed to use 16 rows and a pitch of 1.13, how will the resulting views comprise the scan data?

Answer 11

missing views in the scan data

Question 12

When the pitch is less than one, how do the resulting views comprise the scan data?

Answer 12

overlapping views in the scan data

Question 13

What portions of a patient receive radiation exposure during CT scanning?

Answer 13

Any portion of the patient within the scanner gantry

Question 14

Based on feedback from an American College of Radiology (ACR) site-visit, your imaging department needs to design a new low-dose CT protocol for patients who weigh less than 30 pounds. Which of these detector configurations would be most suited for this protocol?

Answer 14

4 mm x 4 rows

Question 15

How is anatomical data from the scan field of view (SFOC) used during CT image production?

Answer 15

Data from the SFOV is used for image reconstruction

Question 16

Which of following statements accurately describes the orientation of the z-axis in CT imaging?

Answer 16

1. Extends horizontally across the scanner

2. Represents data coordinates in terms of right and left

Question 17

Acquisition thickness refers to the:

Answer 17

Thickness of active detector rows

Question 18

Ct angiography (CTA) imaging of the heart is sometimes performed with the CT scanner in the volume acquisition mode. This means that the

Answer 18

Scan data is acquired in one rotation of the x-ray tube

Question 19

Which of the following statements regarding the scan field of view (SFOV) are true?

Answer 19

1. The SFOV is larger than the display field of view (DFOV)

2. Data in the SFOV is saved on the CT computed system

Question 20

The sequential acquisition mode is described by

Answer 20

The patient table moves only between x-ray exposure

Question 21

What Ct scanning mode induce patient motion artifact from several stops and starts of the gantry table during data acquisition?

Answer 21

Axial mode

Question 22

What portion of the patient can be visualized through the process of the retrospective reconstruction?

Answer 22

only parts of the patient within the scan field of view (SFOV)

Question 23

The helical acquisition mode is the most common technique used for imaging which three body sections?

Answer 23

1. Chest
   2, Abdomen
2. Extremities
   Except cranium and virtually exams

Question 24

During which acquisition mode is the patient table in constant motion?

Answer 24

Helical scanning

Question 25

A CT scanning protocol is set to use a pitch of 0.79. This will result in:

Answer 25

Overlap in the scan data

Question 26

What portion of the CT data collected during a scan is saved by the scanner but not reconstructed for viewing

Answer 26

Any portion of the patient within the scan field of view (SFOV), but outside of the display field of view (DFOV)

Question 27

What CT scanning mode forms a spiral of scan data during imaging?

Answer 27

Helical scanning

Question 28

The inner rows of a non-uniform detector array have the advantage of:

Answer 28

increased spatial resolution

Question 29

During what CT acquisition mode dose the patient table move between x-ray exposures?

Answer 29

Axial scanning

Question 30

The localizer images are used by the technologist to assign which variable of a CT scan?

Answer 30

Display field of view (DFOV)

Question 31

Increasing the acquisition thickness of a CT scan means:

Answer 31

Combining detector rows together to function as one detector row

Question 32

Acquiring a z-axis measurement of pathology is possible in which two imaging planes

Answer 32

1. Sagittal

2. Coronal

Question 33

What is the primary reason for decreasing the detector thickness for CT angiography examinations?

Answer 33

Increased spatial resolution

Question 34

What CT scanning method requires a large detector array with numerous data collection channels?

Answer 34

Volume scanning

Question 35

What is the relationship between acquisition thickness and spatial resolution?

Answer 35

As acquisition thickness increases, spatial resolution decreases

Question 36

Helical (spiral) scanning is usually preferred over axial scanning mode for what three reasons?

Answer 36

1. decreased scan time
2. Improved intravenous (IV) contrast timing
3. Improved post-processing

Question 37

Consider two identical scanning protocols, where one protocol uses a pitch of 0.73 and the other uses a pitch of 0.87. The protocol using a pitch of 0.87 will result in which two of the following differences?

Answer 37

1. Decreased scan time

2. Decreased patient dose