What will it take for laser driven proton accelerators to be applied to tumor therapy?

After many years on the periphery of cancer therapy, the successes of proton and ion beams in tumor therapy are gradually receiving a higher degree of recognition. The considerable construction and acquisition costs are usually invoked to explain the slow market penetration of this favorable treatment modality. Recently, high-intensity lasers have been suggested as a potential, cost-saving alternative to cyclotrons or synchrotrons for oncology. This article will detail the technical requirements necessary for successful implementation of ion beam therapy (IBT)-the general term for proton and heavier-ion therapy. It will summarize the current state of laser acceleration of protons and will outline the very substantial developments still necessary for this technology to be successfully applied to IBT