Question 19M.3.hl.TZ2.26

Any two of:
can be readily “tagged” to variety of biologically active carriers «which will deliver it to specific locations for imaging uses»  [✔]

frequency of radiation is compatible with existing X-ray detection apparatus [✔]

product of decay has low radioactivity/relatively short half-life/low total exposure to patient [✔]

«but small» increased risk of cancer to patient [✔]

must be made on site [✔]

Note: Accept other valid answers outlining advantages or limitations of Tc-99m, such as “produces only LLW”, “Tc is a transition element forming compounds in a variety of oxidation states”, “gamma-radiation «can escape the body and» be detected by external sensors”, “activity decreases quickly, so dose must be calculated prior to each injection”.

ALTERNATIVE 1

$\frac{N(t)}{N_0}={\left(\frac{1}{2}\right)}^{\frac{10}{6.0}}$  [✔]
31 «% remaining» [✔]

ALTERNATIVE 2

λ «= $\frac{\ln 2}{t_{\frac{1}{2}}}$»= 0.1155 hours^–1 [✔]

«$\frac{N}{N_0}$ × 100 = e^–λt ×100 = 0.31498 × 100»

31 «% remaining» [✔]

Note: M1 is for correct substitution of values.

Award [2] for correct final answer.