Development and Evaluation of a PET Dedicated for On-line Imaging and Proton Beam-Range Measurement

A prototype human brain PET dedicated for proton on-line imaging and beam range measurement has been developed and tested with point sources. The PET can be configured in either a closed gantry or open gantry configuration to allow either a full-ring tomographic imaging or a two half-ring imaging for allowing beam passing through the scanner for radiation. Advanced large size (65×65×30 mm3) planar detector and readout electronics with multiplex reduced readout channels were applied. The measured mean energy and coincidence timing resolutions (at the detector level) are ~27.2% and 9.4 ns after corrections. The PET can provide an 18 cm diameter and 6.5 cm axial field of view for proton beam imaging and range measurement. The measured spatial resolution is around ~3 mm uniformly within 6 to 8 cm diameter FOV, and the difference between the acquisitions with closed or open gantry PET configuration is <1.0 mm along the expected beam path over 18 cm length. In summary, the brain PET has been developed and evaluated with sufficient imaging performance for the next on-line imaging. The proton beam range measurement with on-line imaging is under investigation with a new PET gantry and mobile mechanical supporting cart at a clinical proton therapy facility.