Question 19M.3.hl.TZ2.a
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.hl.TZ2.a |
| Level | hl | Paper | 3 | Time zone | TZ2 |
| Command term | Evaluate | Question number | a | Adapted from | N/A |
Technetium-99m, Tc-99m, is a gamma-ray emitter commonly used as a medical tracer.
Its half-life is 6.0 hours.
Evaluate the suitability of technetium-99m for this use.
[2]
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”.
The most frequent response was the short half-life, followed by the emission and detection of gamma radiation.
