Write the atomic symbol for each of the following isotopes used in nuclear medicine:
a.$\mathrm{copper}-64$
b. $\mathrm{selenium}-75$
c. $\mathrm{sodium}-24$
d. $\mathrm{nitrogen}-15$

We need to find atomic symbol for $\mathrm{copper}-64$

As we know copper-$64$is a positron and beta emitting copper isotope with molecular radiotherapy and positron emission tomography applications.

Its atomic symbol is ${}_{29}{}^{64}\mathrm{Cu}$

We need to find atomic symbol for $\mathrm{selenium}-75$

As we know $\mathrm{Selenium}-75$ sources have those advantageous features above$\mathrm{Iridium}-192$ in non-destructive testing (NDT) of thinner-walled steel surfaces, and even some health and safety benefits.

Its atomic symbol is ${}_{34}{}^{75}\mathrm{Se}$

We need to find atomic symbol for $\mathrm{sodium}-24$

$\mathrm{Sodium}24$ is an electrolyte tracer which is used to evaluate whether a person's sodium uptake concentrations are all within acceptable bounds.

Its atomic symbol is ${}_{11}{}^{24}\mathrm{Na}$

We need to find atomic symbol for $\mathrm{nitrogen}-15$

$\mathrm{Nitrogen}-15$, a stable radioisotope of nitrogen that is also an important plant nutrient, is being used to evaluate crop fertiliser effectiveness.

Its atomic symbol is ${}_7{}^{15}\mathrm{N}$