MR Compatible Power Supply Module for PET Detectors of an Integrated PET/MR System

Power supply of positron emission tomography (PET) detectors is a serious issue for PET/magnetic resonance imaging (MRI) systems, due to mutual interaction between power supply electronics and MRI magnetic fields. We developed a prototype of a magnetic compatible power supply, that can be placed in an MRI system. The power supply is a compact (5.2×5.2 cm
²
) iron-free switching dc-dc converter. The power supply works in the very high frequency (VHF) range, between 24.5 and 26.5 MHz, to allow using air core MR compatible inductors, and avoiding RF coupling between harmonics of power supply signal and RF magnetic field of a 1.5 T MRI scanner. The power supply has been designed as an upgrades for the TRIMAGE system and is able to convert 12-V dc input to 5-V dc output with a measured efficiency of 71.43%. Magnetic compatibility has been verified in the 1.5 T magnet of the IRCCS Stella Maris Foundation, Pisa, Italy, and in the 7 T MRI of the IMAGO7 Foundation, Pisa, Italy. Performance measurements of the power supply showed no variations during the magnetic compatibility tests. MRI scanner performance was similar with and without the power supply, and no artifacts were induced by the circuit in the acquired MRI images.