Using radiation in hospitals (a) State one use of ionising radiation in a hospital - Edexcel - GCSE Physics - Question 6 - 2015 - Paper 1

To find the amount remaining after 12 hours, we need to determine how many half-lives fit into 12 hours.

Since the half-life of technicium-99 is 6 hours, in 12 hours there will be:

rac{12 ext{ hours}}{6 ext{ hours/half-life}} = 2 ext{ half-lives}

Starting with 40 mg, after each half-life, the amount will be halved:

• After the first half-life (6 hours):

$40 ext{ mg} imes 0.5 = 20 ext{ mg}$

• After the second half-life (12 hours):

$20 ext{ mg} imes 0.5 = 10 ext{ mg}$

Thus, the amount remaining after 12 hours is 10 mg.

It is important to monitor the amount of radiation a radiographer absorbs each month because excessive exposure to ionising radiation can lead to significant health risks, including the potential for cancer and other cellular damage. Daily monitoring ensures that exposure remains within safe limits and allows for timely intervention if levels are too high.

This is because nowadays, C we have a better understanding of the risks from radiation.