physicsTopic 4 · Atomic StructurePaper 1Grades 8–9
Which isotope should a hospital use?
Starting scenario
Tracer P emits gamma radiation and has a 6 h half-life. Tracer Q emits beta and gamma and has a 3 day half-life. Treatment source R emits gamma with a 5 year half-life. After administration, P activity falls from 48 MBq to 6 MBq in 18 h. Staff dose near an unshielded source is four times higher at half the distance.
You will work through 8 staged questions that build up the science you need. Then you will answer one big-picture question from memory, with no checklist to help you — and only afterwards will the full connection map be revealed.