Biomedical Engineering Reference
In-Depth Information
(a)
According to the ICRP-30 model for the respiratory system,
what is the initial activity deposited in compartment e?
(b)
If the radionuclide has a physical half-life of 32 d, what
fraction of the original activity in compartment e will still
be there after 1 wk?
11.
(a)
Use the data in Fig. 16.4 to find numerical values for the
following quantities for a class-Y aerosol with
AMAD
=
1
µ
m:
D
TB
,
F
d
,
λ
f
,
λ
g
,and
λ
d
.
(b)
If the activity of a class-W aerosol in compartment e of the
ICRP-30 lung model is 10
3
Bq, what is the rate of transfer
of activity from compartment e to the body fluids?
Consider the inhalation of
239
Pu as a class-W aerosol with an
AMAD of 1
µ
m.
(a)
12.
If 50 Bq of
239
Pu is inhaled, how much activity is deposited
in compartment b of the ICRP-30 lung model?
(b)
What fraction of
239
Pu, deposited in compartment b at
time
t
0, clears out of b in the first 24 h?
=
13.
At a certain time following inhalation of a class-W aerosol, the
activities in compartments b and d of the ICRP-30
respiratory-system model are, respectively,
7.8
10
4
Bq and
×
10
4
Bq. What is the rate of transfer of activity to the
gastrointestinal tract?
1.5
×
14.
In the dosimetric model for the GI tract (Fig. 16.8), show
that
λ
B
can be estimated from
f
1
, the fraction of a stable
element that reaches the body fluids after ingestion, by writing
λ
B
=
f
1
λ
SI
/(1 -
f
1
)
.
15.
At a certain time following ingestion of a radionuclide, the
activity in the contents of the small intestine is
2.80 × 10
5
Bq. If
the fraction of the stable element that reaches the body fluids
after ingestion is 0.41, what is the rate of transfer of activity
from the small intestine to the body fluids?
16.
What is the effective half-life of a radionuclide in the body-fluid
transfer compartment, if its radioactive half-life is 8 h?
10
6
Bq of a radioisotope, having a half-life of
2 d, enters the body fluids. How much activity remains in this
compartment at the end of 4 d?
17.
An activity of
5
×
18.
A worker with a burden of
131
I in his thyroid was monitored in
a whole-body counter under fixed conditions of geometry and
counting time. The net number of gamma counts (background
is subtracted) measured from the thyroid was initially 1129.
The net numbers of counts at this and three subsequent times
are shown here. From these data, determine the metabolic
half-life of the iodine in the thyroid.
