Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline

Abstract

Human cancer cells are irradiated by laser-driven quasimonoenergetic protons. Laser pulse intensities at the 5×1019 W/cm2 level provide the source and acceleration field for protons that are subsequently transported by four energy-selective dipole magnets. The transport line delivers 2.25 MeV protons with an energy spread of 0.66 MeV and a bunch duration of 20 ns. The survival fraction of in vitro cells from a human salivary gland tumor is measured with a colony formation assay following proton irradiation at dose levels of up to 8 Gy, for which the single bunch dose rate is 1×107 Gy/s and the effective dose rate is 0.2 Gy/s for 1 Hz repetition of irradiation. Relative biological effectiveness at the 10% survival fraction is measured to be 1.20±0.11 using protons with a linear energy transfer of 17.1 keV/μm.

Dose-controlled irradiation of cancer cells with laser-accelerated proton pulses

“…This work is building on previous work from our group [22] and the radiobiological results are consistent with first experiments performed by Yogo et al [24,25] and a recent single-pulse study of the RBE by Doria et al [26] with retrospective dose evaluation.…”

Biological effectiveness on live cells of laser driven protons at dose rates exceeding 109 Gy/s

“…In the meanwhile, several groups have started preliminary work on the methodology and viability of using laser driven ion source for cell irradiation experiments. [6][7][8] The main aim of these investigations is to establish a procedure for cell handling, irradiation and dosimetry 9 compatible with a laser-plasma interaction environment. Furthermore, one of the peculiarities of laser-driven ion beams is their ultrashort duration, as ions are emitted in bursts of picosecond duration at the source and their therapeutic use may result in dose rates many orders of magnitude higher than normally used.…”

“…in Ref. 8, doses in the Gy range have been delivered to the cells in several fractions. Although each pulse delivered a fraction of a Gray in a short time (tens of ns), the average dose rate over a Gy-level exposure was in the Gy/s range, i.e.…”

A compact solution for ion beam therapy with laser accelerated protons

“…Therefore, L-IBT poses a whole new set of challenges on both physical and biological levels. Laser-driven irradiation technology with all the necessary main components (such as high power laser system and laser target to produce the particle beam, and also beam transport and monitoring as well as dose delivery technique) has already been developed to perform in-vitro cell [26][27][28][29][30][31][32] and small animal [24,26] irradiation with low energy LAP within radiobiological experiments. These recent promising results encourage a go-ahead with further L-IBT solutions.…”

“…Therefore, new methods and techniques for beam transport, irradiation field formation and treatment planning [19][20][21], along with beam-monitoring, dosimetry and dose-controlled irradiation [22][23][24][25][26] are required. Moreover, determination of radio-biological effects induced by ultrashort intense particle bunches [26][27][28][29][30][31][32] is necessary. In addition to laser particle accelerator development, a parallel oncologyfocused research and development is essential to bring this highly promising technology to the clinics.…”