Biomedical Engineering Reference
In-Depth Information
(a)
What is the specific effective energy SEE(testes
←
thyroid)
for a nuclide in the thyroid that emits a 1-MeV photon
in 30% of its transformations, other radiations being
negligible?
(b)
How much total energy is imparted to the testes
(Table 16.1, mass
=
35 g) as a result of 10
9
transformations
of the nuclide in the thyroid?
30.
A radionuclide in the lungs (mass
=
1000 g) emits a 1-MeV
photon in 72% of its transformations. That is the only radiation
that reaches the thyroid (mass
=
20 g). The absorbed fraction,
AF(thyroid
←
lungs), for 1-MeV photons is
9.4
10
-5
.
×
(a)
Calculate the SEE(thyroid
←
lungs) for this nuclide.
(b)
What equivalent dose does the thyroid receive from 10
8
transformations of the nuclide in the lungs?
31.
For a 0.5-MeV photon source in the lungs, the absorbed
fraction for the liver (mass = 1800 g) is
AF(liver ← lungs) = 0.0147. A nuclide in the lungs emits a
single 0.5-MeV photon in 70% of its transformations. This is
the only radiation that reaches the lungs.
(a)
Calculate SEE(liver
←
lungs) for this nuclide.
(b)
Calculate the equivalent dose to the liver per
transformation of the nuclide in the lungs.
32.
A source organ S in the body contains a radionuclide that emits
a 0.80-MeV gamma photon in 90% and a 1.47-MeV photon
in 48% of its transformations. The corresponding absorbed
fractions for a target organ T, having a mass of 310 g, are,
respectively, AF
= 4.4 × 10
-6
and AF
= 1.8 × 10
-6
. Organ T is
irradiated only by these photons.
(a)
Calculate SEE(T
←
S) for this case.
What is the equivalent dose in T as a result of 10
14
transformations of the nuclide in S?
(b)
(c)
If the nuclide has a radiological half-life of 2.0 y and a
metabolic half-life of 6.0 y in S, how long does it take for
the activity in S to decrease by a factor of 10?
33.
A radionuclide emits a 5.80-MeV alpha particle in 60% of its
transformations and a 5.60-MeV alpha particle followed by
a 0.20-MeV gamma photon in 40% of its transformations.
These are the only radiations emitted. A worker has a burden
of 4.1
10
6
Bq of this nuclide in his lungs.
×
(a)
What is the equivalent-dose rate to the worker's lungs
(mass
=
1000 g) from the alpha radiation?
(b)
What is the equivalent-dose rate to the spleen
(mass
=
180 g) if AF(spleen
←
lungs)
=
10
-3
for the
1.47
×
photons?
