Biomedical Engineering Reference
In-Depth Information
41.
A colony of identical cells (unit density) is irradiated with
neutrons, which deposit an average of 125 keV of energy in a
collision. A single neutron collision in a sensitive volume of a
cell inactivates the cell.
(a)
If a dose of 0.50 Gy inactivates 11 % of the cells, what is the
average number of neutron collisions in the sensitive
volume of a cell in the colony?
What is the size of the sensitive volume of a cell in
ยต
m
3
?
(b)
(c)
What fraction of the cells are expected to be inactivated by a
dose of 2.0 Gy?
42.
The survival of a certain cell line when exposed to X rays is
found experimentally to be described by the equation
S
S
0
= 1-(1-e
-0.92
D
)
2
,
where
D
is in Gy. Survival of the same cell line exposed to
neutrons is described by
S
S
0
= e
-0.92
D
,
with
D
in Gy.
(a)
What is the RBE for the neutrons (relative to the X rays) for
10% survival of the cells?
Fig. 13.19
Surviving fraction of cells as a function of dose (Problem 44).
