Flashcard: Medical Imaging Fundamentals — 9 carte

Sampling model — formula?

Discrete sampled function: $f_d(m,n)=f(m riangle x,n riangle y)$.

Discrete sampled function

Sampled at regular grid points in space.

Aliasing — cause?

Under-sampling causes high frequencies to appear as low ones.

Aliasing

Falsely low frequency artefacts from under-sampling.

Nyquist theorem

Prevents aliasing with proper sampling rate.

Nyquist frequency

Half the maximum original frequency.

Anti-aliasing filters

Low-pass filters before sampling.

Image quality measures

Assess image fidelity and diagnostic utility.

Contrast in imaging

Difference in signal intensity between features.