Author Question: 21. In positron emission tomography, when positrons come into contact with a free electron, they are ... (Read 78 times)

jazziefee · **on:** Jun 22, 2018

21. In positron emission tomography, when positrons come into contact with a free electron, they are annihilated. This annihilation produces two byproducts

a) 2 photons
b) 2 protons
c) 2 electrons
d) 2 positrons

Question 2

What does the half-life of a gamma radiation-emitting tracer refer to?

a) The half-life is the time it takes for the substance to reach a non radioactive state
b) The half-life is always 3 days
c) The half-life is the amount of time that the substance requires to begin emitting gamma rays
d) The half-life is the amount of time that it takes for a substance to reach a radioactive state