Question

Yttrium-90 is an important radioactive isotope used by doctors for cancer treatment. The isotope undergoes beta decay with a half life of 64 hrs with no alpha emission and very low amounts of gamma decay. Explain the following phenomenon in terms of ionization and penetration
a) why would alpha decay be a poor choice for use in the human body?
b) why do we use lead shields to cover areas of the body not going through treatment?

Answer 1

1. Alpha particles are a poor choice because they have very little penetrating power.
2. Lead shields are used because lead is a dense metal that has the ability to stop even highly energetic beta and gamma radiation.