Lecture 4: Image registration

Question 1

How can images be registered? (2 marks)

Answer 1

• Using extrinsic markers such as tattoos or markings on immobilisation devices.
• Bony or soft tissue registration. Can be combined with fiducial markers such as small metallic objects (spheres or coils) place in or near to tumour to assist with localisation.

Question 2

How can registration be measured? (2 marks)

Answer 2

We can use a cost-function to compare how well images are registered. Can use geometrically defined features or difference in intensity values within an image.

Question 3

Why do we register images? (2 marks)

Answer 3

To track how well treatment may be working, could be measured by registering and comparing images of a tumour over time.

For delivering treatment; to ensure that the right volume is being treated (motion correction).