A particle CT scanner based on the principle of single particle tracking for path reconstruction through the object (phantom or patient) and single particle calorimetry to estimate residual energy or range calibrated against traversed water equivalent path length has been developed by the pCT collaboration formed in the U.S.A. in 2003. The Phase II version of the system, currently installed at the Northwestern Medicine Chicago Proton Treatment Center, completes a full scan in 6 minutes with a sensitive tracker area of 9 cm (height) and 36 cm (width) in 6 minutes for a high resolution scan using a dose of 1.4 mGy measured with a CTDI head acrylic head phantom. The system produces relative stopping power (RSP) proton CT images with better than 1 percent RSP resolution, artifact free that are reconstructed in less than 5 minutes on an NVidia GPU computer with 2 nodes. Reconstruction algorithms were developed that are based on iterative projection methods solving a large and sparse linear equation system that starts from the initial FDK reconstruction as the initial solution vector and utilizes the superiorization method for noise suppression (talk by Prof. Yair Censor). The system has also been tested with helium ions at the Heidelberg Ion Therapy Center (talk by Lennart Volz) for a fluence modulated pencil beam imaging concept (talk by Dr. Guillaume Landry). The Phase II pCT scanner is available to researchers and developers of clinical pCT systems to gain experience with this new imaging modality, testing new ideas, and facilitating the transition of pCT and particle radiography to the clinical environment.