Radiation Therapy Board Practice Exam 2025 - Free Radiation Therapy Practice Questions and Study Guide

Radon is a naturally occurring radioactive gas that is produced through the decay of uranium and thorium in the earth's crust. The most common isotope of radon is radon-222, which has a half-life of approximately 3.8 days, often which simplifies to about 4 days for general discussions. The concept of half-life is crucial in understanding radioactive decay, which indicates the time it takes for half of a given amount of a radioactive substance to decay into another element or isotope.

A half-life of about 4 days for radon means that if you start with a certain amount of radon gas, after 4 days, only half of that original amount will remain, while the other half will have transformed into stable lead isotopes through a series of decay processes. This relatively short half-life is significant in terms of health concerns, as it indicates how quickly radon can accumulate in enclosed spaces, such as basements, and contribute to potential health risks, particularly in relation to lung cancer when inhaled over prolonged periods of exposure.