1. Advanced Oncotherapy plc
2. Danfysik A/S
3. Elekta AB
4. Hitachi
Ltd.
5. IBA International
6. Koninklijke Philips N.V.
7. Mevion Medical Systems
8. Mitsubishi Electric Corporation
9. Optivus Proton Therapy Inc.
10. ProTom International
11. Provision Healthcare
LLC
12. PTW Freiburg GmbH
13. SAH Global LLC
14. Sumitomo Heavy Industries
Ltd.
15. Toshiba Medical Systems Corporation
16. Varian Medical Systems Inc.