Biomedical Engineering Reference
In-Depth Information
4
Turner, J. E., “Interaction of Ionizing
Radiation with Matter,”
Health Phys.
86
, 228-252 (2004). [Review article in-
cludes electron interactions with mat-
ter and some related health-physics
applications.]
6.9
Problems
Calculate
F
-
(
1.
β
)
for a 600-keV electron.
Calculate
F
+
(
2.
β
)
for a 600-keV positron.
3.
Derive Eq. (6.4) from Eq. (6.1).
4.
Calculate the collisional stopping power of water for 600-keV
electrons.
5.
Calculate the collisional stopping power of water for 600-keV
positrons.
6.
Show that, when
β
1, the collisional stopping-power
formula for an electron with kinetic energy
T
can be written
2
-
d
E
d
x
-
col
=
π
k
0
e
4
n
ln
T
2
2
I
2
+1
.
T
7.
Use the formula from the last problem to calculate the
stopping power of CO
2
at STP for 9.5-keV electrons.
8.
) From Fig. 6.2, estimate for a 100-eV electron the probability
that a given energy-loss event will result in excitation, rather
than ionization, in water.
(
(
a
b
) What fraction of the collisions at 100 eV are due to elastic
scattering?
9.
Use Fig. 6.2 to estimate the fraction of the collisions of a
100-keV electron in water that are due to
(
a
)
ionization
(
b
) excitation
(
c
) elastic scattering.
10.
Estimate the kinetic energy at which the collisional and
radiative stopping powers are equal for electrons in
(
a
)Be
(
b
)Cu
(
c
)Pb.
11.
What is the ratio of the collisional and radiative stopping
powers of Al for electrons of energy
(
a
) 10 keV
(
b
)1MeV
(
c
) 100 MeV ?
12.
Estimate the radiation yield for 10-MeV electrons in
(
a
)Al
