PaNTERA - Proton Radiography towards medical applications

Flash Proton Radiography or Proton Microscopy — developed in the 1990s at the Los Alamos National Laboratory (LANL) — is a diagnostics technique for probing high energy density states of matter. A prototype of the high energy proton microscope facility for FAIR (PRIOR-I) was commissioned in 2014 at GSI in Darmstadt, achieving a spatial resolution of 30 microns with 3.6 GeV protons from the SIS-18 synchrotron [1]. During the course of the PRIOR project it was discovered that, despite the focus on high proton energies and therefore thick or dense targets, proton radiography is also capable of resolving extremely small differences in density. This led to the start of the PaNTERA (Proton Therapy and Radiography) project focussing on medical applications such as proton CT or image guided stereotactic radiosurgery. First experiments with biological targets in the framework of this project were conducted at the PUMA facility at the ITEP in 2011. Since then, various investigations on the eligibility of this technique for medical imaging and applications in treatment planning have been performed at the LANL using also the anthropomorphic phantom „Matroshka“ (from DLR) [2]. Recent developments now focus on overcoming the clinically used Hounsfield lookup table which is required for converting the X-ray Hounsfield units from a conventional xCT to ion stopping power required for heavy ion tumour therapy as well as on improving the image quality at minimum dose especially for proton CT. [1] D. Varentsov et al., “Comissioning of the PRIOR proton microscope,” Rev. Sci. Instrum. 87, 023303 1–8 (2016). [2] M. Prall et al., “High-energy proton imaging for biomedical applications,” Scientific Reports 6, 2765