Why does increasing the kVp in x-ray production increase the number of x-ray photons if the number of electrons produced by the cathode is unchanged? thanks
Is there a relationship between the geometric efficiency of the scanner and computer tomography dose index of a scanner?
I expect the relationship would be inverse but I wanted to check (i.e: if I half the geometric efficency I would double the CTDI(vol).
Is this correct
thanks
Sorry. When I say "basically the same" I mean a high SNR = high NECR...
so they are linearly related...but I clarified this issue with my lecturer..
He said PET has a higher SNR and a higher NECR :)
My question was based on a misunderstanding of the difference between frequency of the RF pulse and Larmor frequency.
I foolishky assumed they were the same which is why I was confused. However problem is now fixed :)
Thanks for your help though :)
The NEC is the true count rate of a theoretical image without any scatter or random events which would give the same statistical quality image as a real image which includes scatter and randoms.
The magnetic moment of protons precesses at a frequency ω0=γB0 about the static magnetic field.
In order to move the magnetisation vector into the transverse plane the RF pulse must be applied at a frequency
ω0. However, as B1 (the field strength of the RF pulse) is << B1 how is this possible...
In PET, 2D PET scanners have a superior SNR to 3D PET scanners as the influence of scatter and random events is lowered by the septa between detector rings. However, the NECR (noise-equivalent count rate), which is linearly proportional to SNR, is higher in 3D PET scanners. These two facts seem...
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...