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

• Published in: Applied physics letters Vol. 98; no. 5; pp. 053701 - 053701-3
• Main Authors: Yogo, A., Maeda, T., Hori, T., Sakaki, H., Ogura, K., Nishiuchi, M., Sagisaka, A., Kiriyama, H., Okada, H., Kanazawa, S., Shimomura, T., Nakai, Y., Tanoue, M., Sasao, F., Bolton, P. R., Murakami, M., Nomura, T., Kawanishi, S., Kondo, K.
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 31-01-2011
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.3551623

Human cancer cells are irradiated by laser-driven quasimonoenergetic protons. Laser pulse intensities at the
5
×
10
19

W
/
cm
2
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
×
10
7

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
/
μ
m
.