Biomedical Engineering Reference
In-Depth Information
19.
Distinguish between the “direct” and “indirect” effects of
radiation. Give a physical example of each.
20.
Give examples of two stochastic and two deterministic
biological effects of radiation.
21.
What are the major symptoms of the acute radiation syndrome?
22.
Given the tenet that the most rapidly dividing cells of the body
are the most radiosensitive, show how it is reflected in the
information given in Table 13.6 for the acute radiation
syndrome.
23.
What are the principal late somatic effects of radiation? Are
they stochastic or deterministic?
24.
According to the BEIR V Report, an acute, whole-body,
gamma-ray dose of 0.1 Gy to 100,000 persons would be
expected to cause about 800 extra cancer deaths in addition to
the 20,000 expected naturally.
(a)
If an “experiment” could be carried out to test this risk
estimate for a dose of 0.1 Gy, would a population of 10,000
individuals be sufficiently large to obtain statistically
significant results?
(b)
A population of 100,000?
(c)
What kind of statistical distribution describes this problem?
25.
Show that
D
0
in Eq. (13.16) is the mean lethal dose.
26.
Survival of a certain cell line exposed to a beam of helium ions
is described by the single-target, single-hit model and
Eq. (13.16). If 25% of the cells survive a fluence of
4.2 × 10
7
cm
-2
, what is the single-target area?
27.
Justify the use of Poisson statistics in arriving at Eqs. (13.16)
and (13.17).
28.
Why do experiments that seek to quantify dose-effect
relationships at low doses require large exposed and control
populations?
29.
Cell survival in a certain set of experiments is described by the
function
S
/
S
0
=
e
-3.1
D
, where
D
is the dose in Gy.
(a)
What is the mean lethal dose?
(b)
What is the LD50?
(c)
What is the difference between LD50 and mean lethal dose?
30.
If 41 Gy reduces the exponential survival of cells to a level of
1%, what is the mean lethal dose?
31.
For multitarget, single-hit survival with
D
0
=
7.5 Gy and an
extrapolation number
n
4, what fraction of cells survive a
=
dose of 10 Gy?
32.
Repeat Problem 31 for
D
0
=
7.5
Gy and
n
=
3
.
33.
Repeat Problem 31 for
D
0
=
5.0
Gy and
n
=
4
.
