An Introduction to Radioactivity

              Radioactivity is the spontaneous emission of radiation which in the form of high energy photons or particles. Radiation occurs when unstable atomic nuclei decay and release particles.The unit used to measure radiation dosage applied to humans is the rem (roentgen equivalent in man). The rem is accounts for the effectiveness of the radiation to cause biological damage to living tissue. The dose of rems determines how much harm a person suffers. A rem is equal to 0.01 sievert in the International System of Units (SI). Radiation damage to the body cells can occur if a person is exposed to radiation through x-imaging, nuclear power or fallout from nuclear weapon. It can also occur after a person receives radiation therapy which used to treat cancer.

              Even radiation will cause biological damage to living cells but not all the cells are equally sensitive to radiation. Those cells which are actively reproducing are more sensitive compare to those cells which are not. This is due to dividing cells requiring correct DNA information for the cell’s offspring to survive. A direct interaction of radiation with the active cells might result in mutation or death of the cells. However, direct interaction of radiation with the DNA of a dormant cell would not have significant effect. Therefore, rate of production of the living cells indicates their sensitivity to radiation; different cells systems have different sensitivities.