David Sang and Graham Jones Solutions for Chapter: Medical Imaging, Exercise 9: Questions

Suggest the reason why, in PET scanning, it is important that the positron meets an electron within a very short distance from its point of emission.

Explain why the gamma rays produced in positron electron annihilation must travel at $180°$ to each other.

Fluorine-18 decays by ${\beta }^{+}$ emission. Write a nuclear equation to show this decay.

(a) Calculate the energy released when a positron and an electron annihilate. (Mass of an electron $=$ mass of a positron $=9.1\times {10}^{-31} \mathrm{kg}.$)

(b) Calculate the frequency of the $\gamma$ -rays emitted when a positron and an electron annihilate.(Mass of an electron $=$ Mass of a positron $=9.1\times {10}^{-31} \mathrm{kg}.$)

(c) Calculate the momentum of the one of the $\gamma$ -rays emitted when a positron and an electron annihilate.(Mass of an electron $=$ Mass of a positron $=9.1\times {10}^{-31} \mathrm{kg}.$)