Highly advanced technologies of a particle therapy of cancer are reviewed. The studied particles are photon, electron, pion, neutron, proton, anti-proton and carbon ion. An attractive feature of a heavy ion therapy system is specially emphasized. It is found that there is a bottleneck of national scale spread. A naive intuition and examination suggest the bottleneck is a throughput of patients where this issue has been little discussed in the past. A possible straightforward solution is mentioned.