MRI QA for RT Planning

Question 1

What are the ideal requirements for an MRI couch for RT planning?

Answer 1

Flat top
Not carbon-fibre
No metal components
Can either use commercial product or customised in house designs

Question 2

What are the requirements of the scanner for RT planning?

Answer 2

MRI compatible lasers
Large bore
Coil supports
Constructed from MRI compatible materials
Location mechanism needs to be compatible with immobilisation devices

Question 3

What imaging factors need to be considered?

Answer 3

Geometric distortion caused by non-linearity in the static magnetic field and non-linearity in the gradient fields
The impact of the RT flat couch top on the image quality
The consistency of image quality parameters

Question 4

What are the scanner based QA tests required?

Answer 4

Magnetic field homogeneity evaluation - geometric distortion
Slice position accuracy
Slice thickness accuracy
RF coil checks - SNR, image intensity, uniformity
High contrast spatial resolution
Artefact evaluation
Centre frequency
Transmitter gain or attenuation
Low contrast detectability

Question 5

What auxiliary equipment QA tests are required

Answer 5

Table accuracy
Laser set-up
Laser movement accuracy

Question 6

What tolerances are needed?

Answer 6

It depends on the phantom design and acquisition parameters

The ACR phantom supports an accreditation program which has documented tolerances