Laser Acceleration of Ions for Radiation Therapy

Abstract

Ion beam therapy for cancer has proven to be a successful clinical approach, affording as good a cure as surgery and a higher quality of life. However, the ion beam therapy installation is large and expensive, limiting its availability for public benefit. One of the hurdles is to make the accelerator more compact on the basis of conventional technology. Laser acceleration of ions represents a rapidly developing young field. The prevailing acceleration mechanism (known as target normal sheath acceleration, TNSA), however, shows severe limitations in some key elements. We now witness that a new regime of coherent acceleration of ions by laser (CAIL) has been studied to overcome many of these problems and accelerate protons and carbon ions to high energies with higher efficiencies. Emerging scaling laws indicate possible realization of an ion therapy facility with compact, cost-efficient lasers. Furthermore, dense particle bunches may allow the use of much higher collective fields, reducing the size of beam transport and dump systems. Though ultimate realization of a laser-driven medical facility may take many years, the field is developing fast with many conceptual innovations and technical progress.

Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

“…Laser ion acceleration works by shooting a high power laser onto a thin target, typically a foil of mm thickness [5]. By hitting the foil the electrons of the target material are accelerated in a plasma and build up a high electric field due to charge separation.…”

“…With much thinner foils (nm) or higher laser intensities, other regimes can become more dominant as e.g. radiation pressure acceleration (RPA) or coherent acceleration of ions by lasers (CAIL) [5]. At the moment, laser-driven protons reach energies up to about 60 MeV [6] which is not sufficient to treat cancer patients as these particles will stop very close to the skin.…”

Laser-Driven Radiation Therapy

“…With a special production technique free-standing foils with 75 % sp 3 bonds -diamond-like bondscan be produced. The thickness of the DLC-foils has been characterized by means of an atomic force microscope (AFM) with an accuracy close to 0.5 nm Tajima (2009). Furthermore, the detailed depth composition -showing also front layer contaminations -was measured via Elastic Recoil Detection Analysis (ERDA) Tajima (2009).…”

“…The thickness of the DLC-foils has been characterized by means of an atomic force microscope (AFM) with an accuracy close to 0.5 nm Tajima (2009). Furthermore, the detailed depth composition -showing also front layer contaminations -was measured via Elastic Recoil Detection Analysis (ERDA) Tajima (2009). A second ingredient in these laser acceleration experiments Henig (2009);Steinke (2010) is an ultra-high contrast of the laser pulses to avoid the preheating and expansion of the target before the interaction with the main laser pulse.…”

A proposed demonstration of an experiment of proton-driven plasma wakefield acceleration based on CERN SPS

“…These so-called plasma accelerators have opened new research frontiers and hold great promise to decrease the scale and therefore the cost of future machines. Developments in these research areas have paved the way for a new generation of plasma accelerators not only for high-energy physics [3] but also for many other applications such as table-top x-ray Free Electron Lasers (FELs) [4], compact proton (carbon) treatment facilities, etc [5]. By employing an ultra-short, ultra-intense laser pulse as a driver, the Laser Wakefield Acceleration (LWFA) at Lawrence Berkeley National Laboratory (LBNL) has successfully demonstrated generation of 1 GeV electron beam in a few centimeter long plasma cell [6].…”