See without being seen: Novel, radiolucent MRI receive arrays for MR-linac and PET/MRI

The MR-linac combines an MRI scanner with a radiotherapy treatment device and enables the visualization of a patient’s anatomy while the treatment is delivered (MRI-guided radiotherapy). However, MRI receive arrays, which pick up the MRI signals, are traditionally not compatible with MRI-guided radiotherapy, as the arrays block too much of the radiation beam. Therefore, special, radiation transparent receive arrays have been developed, which barely attenuate radiation by moving all electronics out of the beam’s path. Unfortunately, the MRI performance of these arrays is lower than that of the conventional arrays. In this thesis, multiple radiation transparent receive arrays have therefore been developed and manufactured to improve the image quality and acquisition speed with respect to the current clinical receive arrays, while barely attenuating radiation. The improved performance can be used to reduce treatment times or to make (real-time) treatment adaptations based on the MR images. Additionally, this thesis has shown that aforementioned receive arrays can be used for hybrid PET/MRI as well. Here, the radiation transparency is required to avoid PET signal absorption by the array and thereby disturbing the PET image reconstruction