Chapter 43, Problem 43.77PP

To determine

The ${}^{123}\text{I}$ be preferred for imaging over ${}^{131}\text{I}$ from the following:

1. (a) The atomic mass of ${}^{123}\text{I}$ is smaller, so the ${}^{123}\text{I}$ particle travel farther through tissue.
2. (b) Because ${}^{123}\text{I}$ emits only gamma-ray photons, the radiation dose to the body is lower with that isotope.
3. (c) The beta particles emitted by ${}^{131}\text{I}$ can leave the body, whereas the gamma-ray photons emitted by ${}^{123}\text{I}$ cannot.
4. (d) ${}^{123}\text{I}$ is radioactive, whereas ${}^{131}\text{I}$ is not.