LIFE01200604005 Shri Somnath Ghosh - Homi Bhabha National ...

CHAPTER 2
MATERIALS AND METHODS
resupplemented with the medium. On an average samples were irradiated for 1 minute to get the
required fluence. The cells were exposed to 2 Gy dose with the help of monitor detector counts.
2.3.3 High LET (heavy ion): For the experiments plateau phase A549 cells were irradiated with
12 C and 16 O ions from 15 UD Pelletron accelerator at the Inter University Accelerator Centre,
New Delhi. During carbon and oxygen irradiation, 35 mm petri plates [NUNC] with cellular
monolayers were kept perpendicular to the particle beam coming out of the exit window. The
petri dishes were kept in the serum free medium in a plexiglass magazine during the irradiation.
The computer controlled irradiation system is such that during the actual irradiation the dish was
removed from medium.
At the cell surface the energy of C ions was 62 MeV (5.16 MeV/u , LET=290 keV/ µm] and the
energy of O ions was 55.8 MeV [LET=614 keV/ µm]. Both the energy and LET were calculated
using the Monte Carlo Code SRIM code [224, 225]. The corresponding fluence for the dose of 1
Gy of carbon was 2.2x10 6 particles cm -2 , thus each cell nuclei can be expected to be physically
traversed at least once by carbon ion. The corresponding fluence for the dose of 1Gy of oxygen
was 1.01x10 6 particles cm -2 , thus each cell nuclei can be expected to be physically traversed at
least once by oxygen ion.
Fluence was calculated using the relation given below [226], approximating the density ρ of
cellular matrix as 1.0:
Dose [Gy] = 1.6 x 10 -9 x LET (keV/ µm) x particle fluence (cm -2 ) x 1/ρ (cm 3 /g)
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