Certified in Public Health (CPH) Practice Exam

Which type of radiation has the greatest ability to penetrate body tissue?

1. a-radiation

2. ß-radiation

3. Gamma-radiation

4. Ultraviolet radiation

The correct answer is: Gamma-radiation

Gamma radiation has the greatest ability to penetrate body tissue due to its high energy and the fact that it is an electromagnetic wave rather than a particle. This allows gamma rays to pass through various materials, including biological tissues, more effectively than alpha and beta particles. Alpha radiation consists of particles that are heavy and positively charged, making them less penetrating; they can be stopped by a sheet of paper or even the outer layer of human skin. Beta radiation, which consists of lighter, negatively charged particles, has more penetrating power than alpha particles but still cannot penetrate deep tissues; it can be stopped by a few millimeters of plastic or a few centimeters of air. In contrast, gamma radiation, as part of the electromagnetic spectrum, can travel through air and tissue and is only significantly absorbed by dense materials like lead or thick concrete. This high penetration capability makes gamma radiation especially concerning in the context of radiation exposure and safety, as it can affect internal organs without requiring direct contact or significant barriers.