CT Image Quality and Noise in Computed Tomography

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What is the relationship between tube current (mA) and image noise in CT imaging?

Tube current and image noise are directly proportional.
Tube current has no effect on image noise in CT.
The relationship between tube current and image noise is complex and depends on other factors.
Tube current and image noise are inversely proportional. (correct)

How does increasing the scan time affect image noise in CT imaging?

Increasing the scan time has no effect on image noise.
Increasing the scan time increases image noise.
The effect of scan time on image noise depends on other factors.
Increasing the scan time decreases image noise. (correct)

What is the relationship between slice thickness and the number of x-rays reaching the detector in CT imaging?

Increasing slice thickness decreases the number of x-rays reaching the detector.
Increasing slice thickness has no effect on the number of x-rays reaching the detector.
Increasing slice thickness increases the number of x-rays reaching the detector. (correct)
The relationship between slice thickness and the number of x-rays reaching the detector is complex and depends on other factors.

How does patient size affect image noise in CT imaging?

Larger patient size increases image noise. (B) Signup and view all the answers

What is the combined effect of tube current and scan time on image noise in CT imaging?

Tube current and scan time have a multiplicative effect on image noise. (A) Signup and view all the answers

Which of the following CT technique factors has the most significant impact on image noise?

Tube current and scan time (mAs) (A) Signup and view all the answers

What effect does increasing slice thickness have on image noise?

Decreases image noise (D) Signup and view all the answers

How does increasing tube voltage (keV) affect image noise?

Decreases image noise (B) Signup and view all the answers

What effect does decreasing tube voltage (keV) have on image noise and contrast?

Increases image noise and decreases contrast (D) Signup and view all the answers

How do patient factors affect image noise?

Larger patients result in more image noise (B) Signup and view all the answers

What is the effect of using a sharp (bone) reconstruction filter on image noise?

Enhances the appearance of image noise (D) Signup and view all the answers

What is the effect of reducing the mAs value on image noise?

Increases image noise (C) Signup and view all the answers

What is the primary cause of image noise in computed tomography (CT)?

Variations in the CT numbers of a uniform material (A) Signup and view all the answers

How is the signal-to-noise ratio (SNR) related to image noise in CT?

A lower SNR indicates less noise in the image (C) Signup and view all the answers

What is the effect of image noise on contrast resolution in CT?

Decreases contrast resolution by hindering the ability to distinguish details (C) Signup and view all the answers

Which factor primarily determines the degree of image noise in CT?

The number of X-ray photons contributing to the image (C) Signup and view all the answers

In CT imaging, what is the conventional average CT number for water?

0 (B) Signup and view all the answers

What is the visual manifestation of image noise in CT?

Grainy appearance on the cross-sectional image (D) Signup and view all the answers