42.11 As part of a radiotherapy course a patient is injected with 0.100× 10-6 mol of an 1.2 MeV a emitter that has a half-life of 52 days, and an RBE of 10. The a emitter is incorporated into molecules which preferentially gather in cancerous tissue and these molecules are flushed completely from the patients system in just four hours. 95% of the a emitter resides in cancerous tissue for this span of time and 5% is dis- tributed throughout the rest of the body. The total mass of cancerous tissue is 35 g and the patient weight 85 kg. You can ignore the variation in activity of the source over the course of the four hours and assume that the source reaches its final distribution throughout the body effectively immediately. (a) What is the decay constant of the a emitter (in s-1)? (b) How many atoms of the a emitter are injected? (c) How many atoms of the a emitter end up in the cancerous tissue?
42.11 As part of a radiotherapy course a patient is injected with 0.100× 10-6 mol of an 1.2 MeV a emitter that has a half-life of 52 days, and an RBE of 10. The a emitter is incorporated into molecules which preferentially gather in cancerous tissue and these molecules are flushed completely from the patients system in just four hours. 95% of the a emitter resides in cancerous tissue for this span of time and 5% is dis- tributed throughout the rest of the body. The total mass of cancerous tissue is 35 g and the patient weight 85 kg. You can ignore the variation in activity of the source over the course of the four hours and assume that the source reaches its final distribution throughout the body effectively immediately. (a) What is the decay constant of the a emitter (in s-1)? (b) How many atoms of the a emitter are injected? (c) How many atoms of the a emitter end up in the cancerous tissue?
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Transcribed Image Text:42.11 As part of a radiotherapy course a
patient is injected with 0.100 × 10-6 mol
of an 1.2 MeV a emitter that has a half-life
of 52 days, and an RBE of 10.
The a
emitter is incorporated into
molecules which preferentially gather
in cancerous tissue and these molecules
are flushed completely from the patients
system in just four hours.
95% of the a emitter resides in cancerous
tissue for this span of time and 5% is dis-
tributed throughout the rest of the body.
The total mass of cancerous tissue is 35 g
and the patient weight 85 kg.
You can ignore the variation in activity
of the source over the course of the four
hours and assume that the source reaches
its final distribution throughout the body
effectively immediately.
(а)
What is the decay constant of the a
emitter (in s-1)?
(b) How many atoms of the a emitter
are injected?
c) How many atoms of the a emitter
end up in the cancerous tissue?
(d) What is the activity of the a emitter
in the cancerous tissue (in Bq and
Ci)?
Because the radioactive source is an a
emitter, 100% of the a particles will be ab-
sorbed in the tissue in which the are emit-
ted.
(e) How many a particles are absorbed
by the cancerous tissue over the pe-
riod of four hours before it is flushed
from the body?
(f) What is the energy deposited in the
cancerous tissue (in J)?
(g) What is the dose received by the
cancerous tissue (in Sv)?
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