The evolution of nuclear medicine—a field focused on the use of radioactive substances and chemicals—is profoundly influenced by the contributions of talented scientists from various disciplines, including physics, chemistry, engineering, and medicine. The interdisciplinary character of nuclear medicine complicates the task for medical historians in pinpointing its inception. Nevertheless, many historians regard the invention of artificially generated radioisotopes, utilized in nuclear radiation therapy, which falls under the domain of nuclear radiation physics, as the most pivotal achievement in nuclear medicine.
Indeed, the field of nuclear radiation physics made a significant impact on medicine with the advent of X-rays and the discovery of natural radioactivity over a century ago, and the possibilities for medical imaging and treatment stemming from these breakthroughs were swiftly acknowledged. Nuclear radiation linked to nuclear energy is termed ionizing radiation. Figure 1.1 illustrates the schematic representation of nonionizing radiation and ionizing radiation along with their applications in various sectors.
85.5% of the overall radiation, which includes both natural and artificial sources, consists of 71% telluric radiation and approximately 14.5% cosmic radiation. Radiation that is specifically linked to nuclear medicine and the application of nuclear energy, as well as X-rays, is classified as ionizing. Nevertheless, not all radiation sources possess adequate energy to engage with matter, particularly the human body, and generate ions. Table 1.1 illustrates various types of rays that humans have encountered.
Ionizing radiation, possessing adequate energy to engage with matter, particularly within the human body, has the ability to generate ions; it can remove an electron from a DNA (deoxyribonucleic acid) atom [8–11]. Consequently, the bonding characteristics of the DNA atom are altered, leading to a physical transformation of the DNA. Figure 1.2 illustrates the impaired DNA molecule that governs essential cellular processes.
A spark chamber serves as an exemplary tool for visually demonstrating electrically charged particles resulting from ionizing radiation. This apparatus is primarily utilized in the field of particle physics to detect electrically charged particles. It is composed of metal plates situated within a sealed enclosure filled with helium, neon, or a combination of both gases. As a charged particle traverses the detector, it ionizes the gas present between the plates. Nevertheless, this ionization is not visible until a high voltage is applied across the plates. The application of high voltage generates a spark that follows the path taken by the cosmic ray.
Under specific circumstances, ionizing radiation has the potential to harm living organisms, leading to cancer or genetic damage.
Similarly, non-ionizing radiation can also inflict damage on living organisms under certain conditions, resulting in issues such as burns. In 2011, the International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), issued a statement that included radio frequency electromagnetic fields (which encompass microwave and millimetre waves) in their classification of agents that may be carcinogenic to humans.genic to humans.
Source:
https://www.who.int/news-room/fact-sheets/detail/ionizing-radiation-and-health-effects
