A PET/MR compatible device for production of Radiowater

Perfusion studies can be performed with fMRI or using radioactive perfusion tracers such as 15O radiowater. Hybride imaging with PET/MRI allows simultaneous perfusion studies with two different metdos. A novel PET MR compatible Hidex automatic Radiowater Generator (RWG) based on two-membrane diffusion chamber technique was designed. Cyclotron produced 15O2 gas is converted with H2 gas in a furnace to water vapour. A copper RF feed through for radioactive plastic gas lines was installed on the floor of the scanner room next to the Hidex lead shield. O-15 labelled water is led in gas phase, water vapour, under the RF cage into the lead shield of the Hidex RWG. Radioactive water vapour is mixed with saline in a sterile diffusion chamber. The system is designed for continuous and bolus production of radiowater with 600 to 1200 ml/min saline flow. The system can also be used for proton only cyclotrons. The Hidex RWG is designed to fulfil special requirements when installed next to a PET MR device. The Hidex RWG is installed at 3 metres distance from the 3T MRI scanner in about 0.75mT field strength. The lead shield is paramagnetic and in the diffusion chamber integrated pinch valves are operated with compressed air. Positron sensitive radioactivity detectors for recording production rate and the injected dose are based on fibre optics coupled with plastic scintillators. Photomultiplier tubes and all control electronics are installed in the control room of the Philips Ingenuity TF PET MR.