Biomedical Engineering Reference
In-Depth Information
10
3
a
b
H
2
O liquid
10
2
H
2
O liquid
10
1
10
1
10
0
H
2
O vapor
10
-1
10
-2
10
-3
10
0
H
2
O vapor
10
-4
10
-5
10
-6
10
-1
10
-7
10
1
10
2
10
3
10
4
10
1
10
2
10
3
10
4
Incident energy (keV/amu)
Incident energy (keV/amu)
Fig. 16.8
Ionization and capture total cross sections for H
C
in liquid and gaseous water both
described within the CNDO approach. Panel (
a
): Ionization: CB1 and CDW-EIS results (solid and
dashed line, respectively). Panel (
b
): Capture: CDW and CDW-EIS results (solid and dashed line,
respectively)
It has been shown [
65
,
66
] that multiple ionization of water irradiated by high
linear energy transfer-ion beams is responsible for the creation of a large amount of
HO
2
=O
2
radicals and O
2
molecules in liquid water radiolysis in agreement with
experiments [
67
,
68
]. These radicals interacting with DNA can provoke damage to
biological matter.
16.5.5
From water to DNA
Total cross sections for electron ionization and electron capture from Adenine by
proton beams are presented in Figs.
16.10
aand
16.10
b, respectively. The target is
described by using the CNDO representation presented in Table
16.3
within the
CB1 and CDW-EIS approximations for ionization and the CDW-EIS and CDW
ones for capture. The only available experimental points [
69
,
70
] are also reported
for comparison. Thus, for ionization, we first observe in Fig.
16.10
a that the
experimental data at 80 keV (taken from [
69
]) is largely underestimated by both
theories whereas the recent measurement reported by Iriki et al. [
70
]at1MeVis
well reproduced by the two models. We observe also that the CB1 and the CDW-EIS
calculations are in reasonable agreement for impact energies larger than 100 keV.
