Tomographic imaging & reconstruction

Question 1

ct Imaging geometries

Answer 1

pencil beam
parallel beam
fan beam
cone beam

Question 2

“filtered back projection” requires

Answer 2

interpolation

Question 3

Ram-Lak is sensitive to

Answer 3

noise in projections

Question 4

Kaczmarz method

Answer 4

• Start with initial guess of f, e.g. zeros, or random, or previous FBP
• Forward-project guess for (n-1)th iteration and i
  th angle that would be the measured projection in case f(n-1) would be correct
• calculate difference to measured projection
• Back-project difference along ray
• Update guess with back-projected difference

Question 5

Kaczmarz method Also known as

Answer 5

Algebraic Reconstruction Technique (ART)

Question 6

ART disadvantages over FBP

Answer 6

• Much slower
• More complicated, harder to implement and understand
• Potentially numerically unstable, may need regularization
• New (doctors don’t like change)