Chapter 21, Problem 21.77QP

Interpretation Introduction

Interpretation: A patient is given to be injected with a $\text{5}\text{μM}$ solution of gallium citrate containing ${}^{68}\text{Ga}\left(t_{1/2}=9.4\text{h}\right)$ for a PET study. The time in which the activity of ${}^{68}\text{Ga}$ drops to $5\%$ of its initial value is to be calculated.

Concept introduction: Isotopes are the species of same element which differ only by the number of neutrons or by mass number.

There are various isotopes of gallium. Some of them, ${}^{67}\text{Ga}$ and ${}^{69}\text{Ga}$. The radio isotopes which are commercially most important are ${}^{68}\text{Ga}$ and ${}^{67}\text{Ga}$.

The isotope which is used in medicines is gallium- $68$ ${}^{68}\text{Ga}$.

To determine: The time in which the activity of ${}^{68}\text{Ga}$ drops to $5\%$ of its initial value.