Most of these biological effects are stimulated by nuclear DNA (nucDNA) damage. We first need to understand a little bit about the structure of DNA. The biological effect of this radiation depends not only on the amount of the absorbed dose but also on the intensity of the ionization in the living cells caused by different types of radiation. The absorbed dose quantifies the energy imparted per unit mass absorbing medium, but does not relate this value to radiation damage induced in cells or tissue. A dose unit more closely related to effects in biological tissue is called the roentgen equivalent man or rem and is defined to be the dose in rads multiplied by the relative biological effectiveness. A dose unit more closely related to effects in biological tissue is called the roentgen equivalent man or rem and is defined to be the dose in rads multiplied by the relative biological effectiveness. The genetic material of the cell is found in the nucleus in the form of genes which are in turn combined into strand-like structures called chromosomes. Radiation damage is the effect of ionizing radiation on physical objects. Health effects of ionizing radiation. The potential damage from an absorbed dose depends on the type of radiation and the sensitivity of different tissues and organs. In short, the biological damage from high-LET radiation (alpha particles, protons or neutrons) is much greater than that from low-LET radiation . DNA is a very long molecule that stores our genetic information. To understand how ionizing can affect or even damage the cells in our bodies. The radiation that was released by the explosions, however, caused the deaths of many people weeks, months, and even years later. Why does radiation damage the body? For example after receiving a lethal dose of 10 Gy, the body temperature will only increase by 0.02 °C but the dose may lead to death of all the exposed entities. The RBE always compares the amount of orthovoltage radiation to another type of radiation (e.g. Biological damage from radiation begins with this ionizing effect. Normal tissue responses to ionizing radiation have been a major subject for study since the discovery of X‐rays at the end of the 19th century. Ionizing radiation (ionising radiation) is radiation, traveling as a particle or electromagnetic wave, that carries sufficient energy to detach electrons from atoms or molecules, thereby ionizing an atom or a molecule. Shortly thereafter, time–dose relationships were established for some normal tissue endpoints that led to investigations into how the size of dose per fraction and the quality of radiation affected outcome. What’s RF – Ionizing RF Radiation – non- Ionizing RF “Ionization” is a process by which electrons are stripped from atoms and molecules. It lies curled up inside the nucleus of a cell. For example we have brain cells, muscle cells, blood cells etc. Radiation poisoning, also called radiationsickness or a creeping dose, is a form of damage to organ tissue due to excessive exposure to ionizing radiation. For example, neutron, proton and alpha radiation can cause 5-20 times more harm than the same amount of the absorbed dose of beta or gamma radiation. The energy is enough to damage DNA, which can result in cell death or cancer. The other acknowledges that any radiation hit will injure cells and eventually it will accumulate damage enough to make itself known as a cancer or precancer. Ionizing Radiation Definition. The relative biological effectiveness (RBE) or quality factor (QF) is given in Table 1 for several types of ionizing radiation—the effect of the radiation is directly proportional to the RBE. Radiation, Biological Damage ABDEL HAKIM BEN NASR BRIAN HOYLE The nuclear explosions at Hiroshima and Nagasaki, Japan on August 6 and 9, 1945, demonstrated the immense power of the nuclear bomb.The effects of the explosion were immediate. For example, alpha particle radiation absorbed in tissue is considered to be about 20 times more effective as a carcinogen than the same dose of gamma rays. This is known as the equivalent dose. Certain anti-oxidents can help repair damage. These aggregates can swell and make the shield mechanically unsound. [91] This ability to disrupt chemical bonds means that ionizing radiation focuses its impact in a very small but crucial area, a bit like a karate master focusing energy to break a brick. A dose unit more closely related to effects in biological tissue is called the roentgen equivalent man or rem and is defined to be the dose in rads multiplied by the relative biological effectiveness. Ionizing radiation is relatively high in energy, and when it collides with an atom, it can completely remove an electron to form a positively charged ion that can damage biological tissues. The relative biological effectiveness (RBE) or quality factor (QF) is given in Table 2 for several types of ionizing radiation—the effect of the radiation is directly proportional to the RBE. This process can produce molecular changes that can lead to damage in biological tissue, including effects on DNA,genetic material.This process requires interaction with high levels of electromagnetic energy. All exposures to ionizing radiation carry a risk of biological damage, although this risk decreases as the exposure decreases. The most important long-term effect of radiation exposure is an increased chance of getting cancer. It includes the various effects caused by different types of ionizing radiation, the tissue type into which the energy is imparted, the biological effect under investigation, and the rate at which that dose is delivered. Ionizing radiation and the products of the cleavage of water are able to damage all biological macromolecules, including… aging: Ionizing radiation The shortening of life caused by ionizing radiation (e.g., X-rays) has been determined for many species, including mice, … Ionizing radiation is more harmful than nonionizing radiation because it has enough energy to remove an electron from an atom and thereby directly damage biological material. For example, the risk associated with natural background radiation is very small, although elevated levels of naturally occurring radon increase the risk of lung cancer. This is because the living tissue can more easily repair damage from radiation that is spread over a large area than that which is concentrated in a small area. Anyone who has received a sunburn knows that ultraviolet light can damage skin cells. Ionizing Radiation • Ionizing radiation − Composed of particles that individually carry enough kinetic energy to liberate an electron from an atom or molecule − Kinetic energy > 12.4 eV Biological Radiation Effects 3 Non-ionizing radiation Ionizing radiation Ionization energy of soft tissue 12.4 eV or 100 nm According to the IAEA, ionizing radiation has a direct action on the complex vital molecules (for example the DNA) within the cell by breaking the bonds between the atoms. By contrast, evidence has emerged concerning “bystander” responses involving damage to nearby cells that were not themselves directly traversed by the radiation. Radiation damage to tissue and/or organs depends on the dose of radiation received, or the absorbed dose which is expressed in a unit called the gray (Gy). Before discussing the biological effects of radiation, we will consider ionizing radiation interactions in tissue. It is the genes within a cell that determine how a cell functions. The body is made up of different cells. 2 Ionizin g Radiation Effects on Cells, Organe lles and Tissues on Proteome L ev el 45 The label-free approach enables the quantita- ti ve measurement of radiation-induced alterations Non-ionizing radiation behaves exactly like ionizing radiation, but differs in that it has a much greater wavelength and, therefore, less energy. Alpha particles do not penetrate very far into matter, whereas γ rays penetrate more deeply. Absorbed dose, D, is defined as the quotient of mean energy, dε, imparted by ionising radiation in a volume element and the mass, dm, of the matter in that volume (Cember, 1969). 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