Laser-driven ion accelerators for tumor therapy revisited

Ten years ago, the authors of this report published a first paper on the technical challenges that laser accelerators need to overcome before they could be applied to tumor therapy. Among the major issues were the maximum energy of the accelerated ions and their intensity, control and reproducibility of the laser-pulse output, quality assurance and patient safety. These issues remain today. While theoretical progress has been made for designing transport systems, for tailoring the plumes of laser-generated protons, and for suitable dose delivery, today’s best lasers are far from reaching performance levels, in both proton energy and intensity to seriously consider clinical ion beam therapy (IBT) application. This report details these points and substantiates that laser-based IBT is neither superior to IBT with conventional particle accelerators nor ready to replace it.

Figure 1

Number of active ion beam therapy facilities and patients treated. Ions $\mathrm{A}>1$ designate ions heavier than protons (data from PTCOG statistics [9]).

Figure 2

Two examples of commercial single-room proton therapy facilities. Top: Mevion S250™, Mevion, Littleton, MA, USA. Building volume approximately $14\times 14\times 14{\mathrm{m}}^3$ (data from [7]). Bottom: ProteusOne™ Ion Beam Applications, Louvain-la-Neuve, Belgium. Building volume approximately $13\times 14\times 27{\mathrm{m}}^3$ (data from [44]).