Why
does a Mo/Tc generator contain 50 lb of lead shielding?
a.
To shield Mo-99 parent
b.
To shield Tc-99m
daughter
c.
To shield Tc-99g
granddaughter
d.
To shield Ru-99 great
granddaughter
ANSWER
a.
To shield Mo-99
parent. It takes only
a few pounds of lead to completely shield Tc-99m.
Why are
you not concerned for your patients’ safety if 10 mCi of 99mTc
sulfur colloid is injected into a patient? 99mTc-sulfur colloid
never clears the liver. All of it will ultimately decay into 99Tc,
which has a tphys of 2.2 X 105
yr.
ANSWER
Since the tphys
is 2.2 X 105 yr, the rate of decay is only 0.000003 per year. During
the patient’s lifetime, the number of decays is negligible compared to
background radiation.
ANSWER
