Systems and Components

Question 1

The principal advantage of thin detector rows is:

Answer 1

Higher spatial resolution

Thinner detector rows can image smaller parts, which is essential the definition of high spatial resolution. The downside is that this usually requires a higher tube output, which increases patient dose. The width of the detector rows may or may not affect the scan time.

Question 2

The width of the x-ray beam is controlled by:

Answer 2

Collimation

The shape of the x-ray beam as it leaves the x-ray tube is controlled by the pre-patient collimators. Matrix sizes and other technical settings have no influence on this. Only the collimators change the actual width/ geometry of the beam.

Question 3

The main difference between image production in CT compared to image production in radiography is

Answer 3

Projections are compiled into a 3D volume of data

Question 4

A single “view” acquired during a CT scan is also called a:

Answer 4

Projection

Question 5

Physical components located inside the computed tomography (CT) gantry typically include which two of the following?

Answer 5

1. X-ray tube

2. High-voltage generator

Question 6

Calculate the total beam width of a CT scan using 32 detector rows, 0.5 mm detectors, 100 milliamperage (mA), and 140 kilovoltage peak (KVp):

Answer 6

16 mm

Question 7

The signal produced by a CT detector is a (n):

Answer 7

Analog electrical signal

When detectors capture remnant x-ray photons, they produce an electrical signal that is proportional to the number of photons they received. More photons means a stronger signal. This electrical signal is sent to other components of the scanner where it is converted to a raw (unprocessed) digital signal and later a digital image (processed) signal that is suitable for viewing.

Question 8

Which component of the CT imaging system is responsible for creating reconstructed image data?

Answer 8

Computer system

Question 9

The phrase “8-slice scanner” refers to a CT imaging system that has:

Answer 9

8 detector rows

Question 10

Which of the following is a common voltage (KVp) setting used in CT?

Answer 10

120 KVp

Most CT scanners are equipped with a limited number KVp options, which includes 80,100,120, and 140 KVp. Higher and lower KVp settings are not possible

Question 11

Increasing the milliamperage (mA) and voltage (KVp) of a CT scan will usually result in which two of the following?

Answer 11

1. Increased patient dose

2. Decreased image noise