Term
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Definition
| Biologic damage occurs as a non-secondary process of ionization of atoms on essential molecules, which may cause these molecules to become either inactive or functionally altered. Action is direct when biological damage occurs as a result of the ionization of atoms on essential molecules (DNA, RNA, proteins, enzymes) produced by straight interaction with the incident radiation. |
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Term
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Definition
| The damage effects, on key molecules, produced by free radicals that are created by the interaction of radiation with water molecules; cell death can result. action is indirect when effects are produced by free radicals created by the interaction of radiation with water molecules; these unstable, highly reactive chemical combinations can cause substantial disruption to vital macromolecules such as DNA and result in cell death. |
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Term
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Definition
| Solitary atoms, or most often a combination of altered atoms, are very chemically reactive as a result of the presence of unpaired electrons. |
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Term
| LET- linear energy transfer |
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Definition
| LET is the average energy deposited per unit length of the track by ionizing radiation as it passes through and interacts with the medium along its path. |
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Term
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Definition
| Low-LET radiation (x-rays and gamma rays) doses that are not excessive primarily cause indirect damage to biologic tissues that usually can be reversed by repair enzymes. |
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Term
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Definition
| High-LET radiation (alpha particles, ions of heavy nuclei, and low-energy neutrons) can produce irreparable damage to DNA because of inducing multiple-strand breaks that cannot be undone by repair enzymes. |
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Term
| RBE-related biologic effectiveness |
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Definition
| RBE of type of radiation being used is the ratio of the dose of reference radiation to the dose of radiation of the type in question that is necessary to produce the same biologic reaction in a given experiment. The response is what is provided by a dose of test radiation delivered under the same conditions. |
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Term
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Definition
| Radiation-induced biologic damage in living systems is observed on molecular, cellular, and organic system levels. |
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Term
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Definition
| It states that when a vital macromolecule or target such as cell DNA is directly or indirectly inactivated by exposure to radiation, the cell will die. |
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Term
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Definition
| When a cell nucleus is significantly damaged by exposure to ionizing radiation, the cell can die or experience reproductive death, apoptosis, mitotic death, mitotic delay, or interference with function. |
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Term
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Definition
| Apoptosis is a nonmitotic or nondivision form of cell death that occurs when cells die without attempting division during the interphase portion of the cell life cycle. Also, know as programmed cell death/ interphase death |
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Term
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Definition
| The cell survival curve is used to display the radiosensitivity of a particular type of cell, which helps determine the types of cancer cells that will respond to radiation therapy. |
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Term
| The Law of Bergonie and Tribondeau |
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Definition
| It states that the most pronounced radiation effects occur in cells with the least maturity and specialization or differentiation, the greatest reproductive activity, and the longest mitotic phases. |
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Term
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Definition
| embryo-fetus is very susceptible to radiation damage, which can cause CNS anomalies, microcephaly, and intellectual disability. |
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Term
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Definition
| Lymphocytes are the most radiosensitive blood cells, and when they are damaged the body loses its natural ability to combat infection and becomes more susceptible to bacterial and viral antigens. |
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Term
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Definition
| Because the body continually regenerates epithelial tissue, the cells comprising this tissue are highly radiosensitive. |
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Term
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Definition
| Muscle is relatively insensitive to radiation |
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Term
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Definition
| Radiolysis of water- ionization interaction of radiation with water molecules resulting in a separation into oxygen and hydrogen components. |
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Term
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Definition
| Changes in genes are caused by the loss or change of a nitrogenous base on the DNA chain. It is generally the result of the direct or indirect interaction of high-energy radiation with a DNA molecule. |
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Term
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Definition
| The segmenting of a chromosome is due to the breaking of one or both of the sugar-phosphate chains of a DNA ladder-like structure, which is a potential outcome when ionizing radiation interacts with a DNA macromolecule. |
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