Optimizing Brain Imaging Protocols: Advanced Acquisition Techniques for Radiotherapy with Immobilization Masks

Motivation: MRI is crucial for brain tumor radiotherapy planning, registered with CT for dose calculation. Using a custom thermoplastic mask during MRI improves targeting but limits the use of the standard head coil. Goal(s): This study aims to optimize MRI image quality for radiotherapy with the thermoplastic mask by testing different coil configurations. Approach: Various coil setups were tested, combining 4- and 18-channel coils. Each configuration was evaluated by a radiation oncologist and physicist, focusing on signal-to-noise ratio and spatial resolution. Results: The best image quality was achieved with the combination of 4 FS and 18 UFL coils, which was adopted for clinical use. Impact: The radiotherapy mask during brain MRI renders the head coil unusable. This work significantly improved image quality with a custom setup: a 4-channel Flex coil at the back and an 18-channel UltraFlex coil around the top of the patient's head.