Radiation Therapy Physics

Radiation should be considered a double-edged sword. This is because radiation can kill, as demonstrated by the outcome of the dropping of atomic bombs at Hiroshima and Nagasaki in Japan and the disastrous incidents at nuclear reactor plants around the world, most recently at Chernobyl, Ukraine in April 1986. On the other hand, radiation can cure, as applied extensively in the diagnosis and treatment of diseases since the discovery of x-rays and radioactivity. The word “Gamma knife” was coined by a neurosurgeon for a machine using gamma radiation as a knife to surgically remove lesions in the brain. We know that radiation plays an integral role in the practice of modern medicine. For those of us who are interested in the medical use of radiation, radiation should be understood and respected as a potent tool. The outcome of this respect is the safe and proper use of radiation to derive the maximum benefit to mankind. In this first chapter, we shall introduce the medical use of radiation and then proceed with examining the nature and different types of radiation. Next, radiological quantities and units shall be presented. We shall also examine the sources, ionizing effects, and safe handling of radiation and sources. Lastly, a historical perspective of radiological physics and its branches shall be dealt with in this chapter.