Signal to noise ratio in a CT scanner

AI Thread Summary
The discussion revolves around calculating the signal-to-noise ratio (SNR) in a CT scanner when various parameters are altered, including tube current, pitch, rotation time, and slice width. A participant attempts to derive the new SNR value based on these changes, initially suggesting the answer remains N. There is a suggestion to consult textbooks for relevant equations and the influence of these changes on SNR, but the participant indicates they have not purchased any due to cost. The participant acknowledges potential errors in their calculations but still questions if the final answer is correct. The conversation highlights the importance of understanding the effects of CT parameters on image quality.
BobP
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Homework Statement


If the relative noise (noise divided by signal) in a region of a CT slice is measured to be N what would be the value if the tube current was halved, the pitch increased from 0.9 to 1.2, the rotation time increased from 0.75s to 1s and the slice width increased from 1mm to 2mm.

Homework Equations

The Attempt at a Solution


I think the answer is N
Working: sqrt(0.5*(1/0.75)*(0.9/1.2)*2)
but am not certain
 
Last edited:
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Doesn't your textbook have any discussion of the influence of any of those changes? There must be some relevant equations. You should learn them.
 
FactChecker said:
Doesn't your textbook have any discussion of the influence of any of those changes? There must be some relevant equations. You should learn them.
My course is entire lecture-based and we were told we didn't need books. as they are so expensive I didn't buy any. I did a google search but couldn't find anything Having said that I realized I probably got two things in the working the wrong way around but the answer is still N? right?
sqrt(0.5*(0.75/1)*(1.2/0.9)*2)
 
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