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rad rev on ppt
radiobiology review from power points
| Question | Answer |
|---|---|
| Radiobiology | The study of the effects of radiation on biologic tissue aka. The marriage of radiologic physics and biology |
| Roentgen | 1895 |
| Becquerel | 1896 |
| Curie’s discovery | 1898 |
| Us fatality | 1904 |
| Law of b and t | 1906 |
| The pamphlet of American college of radiology states | Effects from x radiation may be more severe than nuclear testing 1962 |
| Dose limit | 50 mSv per year/ 10 mSv x age = cumulative |
| Cell theory | All living organisms are composed of cells (unicellular or multicellular), cells arise from preexisting cells, cell is the basic unit of life |
| Cell biology | Tissues, organs, systems, organisms |
| Protoplasm | the living contents of a cell that is surrounded by a plasma membrane aka. Cytoplasm |
| Inorganic compounds of protoplasm | Water and minerals |
| Organic compounds of protoplasm | Protein, carbohydrates, nucleic acids and lipids |
| Cell structure | Cell membrane, cytoplasm, and cytoplasmic organelles |
| Cytoplasmic organelles | Endoplasmic reticulum, mitochondria, ribosomes, lysosomes, and golgi apparatus |
| Endoplasmic reticulum | involved in the synthesis of proteins, membrane factory for the cell, smooth e.r. are involved in the synthesis of lipids |
| Mitochondria | "cellular power plants" generate most of the cell's supply of chemical energy involved in cellular differentiation, cell death, as well as the control of the cell cycle and cell growth |
| Ribosomes | protein-synthesizing machines of the cell |
| Lysosomes | digest things. They might be used to digest food or break down the cell when it dies. |
| Golgi apparatus | cell structure mainly devoted to processing the proteins synthesized in the endoplasmic reticulum (ER) |
| Nucleus | Nuclear membrane, nucleolus, nucleo plasm, DNA, and RNA |
| Radiation damage to the cell | All parts of the cell are at risk from this exposure |
| Two types of cells | Somatic and genetic (germ) cells |
| Somatic cells | All cells except for genetic or reproductive cells. They undergo mitosis |
| Genetic (germ) cells | Reproductive cells, undergo meiosis |
| Chromosomes | Linear threads in the nucleus that contain DNA |
| 46 chromosomes or 23 pair : 2N or diploid number | what are in somatic cells |
| 23 chromosomes or 22 autosomes and 1 sex cell: haploid number | What are in genetic cells |
| Genes | Basic unit of heredity |
| Alleles | Gene pairs (can be either heterozygous or homozygous) |
| Mitosis | Process of somatic cell division where parent cell divides to produce 2 daughter cells identical to the parent cell |
| Four phases of cell division | |
| Cell during interphase | During s phase, Chromosomes change from a 2 chromatid to a 4 chromatid configuration |
| Prophase | The nucleus swells, chromatids are visible, nucleus membranes disappears, DNA take structural form, chromosomes divides forming centrioles which move to opposite poles |
| The process of Interphase, prophase, metaphase ,anaphase, telophase = | Daughter cells |
| Metaphase | Mitotic spindles form between the centrioles, chromosomes line up, centromere duplicate, chromatids attach to mitotic spindle and mitosis can be stopped and studied |
| Anaphase | Daughter chromsomes formed, pulled toward their respective centriole |
| Telephase | The nuclei begin to form at opposite poles, nuclear membranes form, daughter chromosomes uncoil, cytoplasm divides equally, and cells are now independent then process starts all over again |
| Meosis | Special type of cell division occurring in germ or reproductive cells, reduces the number of chromsomes in each daughter cell to half the number of chromsomes in the parent cell |
| Phases of Meosis | Meosis I, interphase, prophase, metaphase, anaphase, telophase ; Meosis II, prophase, metaphase, anaphase, telophase |
| Malignant cells | Cancer cells that may be normal in size or may vary greatly in size and shape from normal cells |
| How do malignant cells vary from normal cells | They have increased amount of chromatin and increased amount of nuclear material to cytoplasm |
| Sensitivity of a cell to radiation is determined by what | State of maturity and its functional role in the body |
| H to L sensitivity in Tissues | Epithelial, muscle, connective and nervous |
| H to L sensitivity in Organs | Nervous, reproductive, digestive, respiratory, endocrine |
| Factors affecting radiosensitivity | |
| Body is how much water | 70 to 85 % |
| Highest Cellular type sensitivity to radiation | Lymphocytes, spermatagonia, erythroblasts, rapid reproduction |
| Intermediate cellular type sensitivity to radiation | Endothelial, osteoblasts, spermatids, fibroblasts, all mature and less reproduction |
| Low cellular type sensitivity to radiation | Muscle, nerve, chondrocytes, mature and slow reproduction |
| Law of b and t | the radio-sensitivity of a cell is directly proportional to their reproductive activity and inversely proportional to their degree of differentiation |
| LET- linear energy transfer | Measure of rate at which energy is transferred from ionizing radiation to the soft tissue; method of expressing radiation quality or how damaging a particular type of radiation is |
| What is LET expressed in | KeV/m |
| Diagnostic x ray is what KeV/m | 3 |
| Direct interactions are related to | High LET |
| Indirect interactions are related to | Low LET |
| High LET radiation causes | Greater amounts of damage over a shorter tract of time |
| Low LET radiation causes | Lower amount of damage over a longer tract of time |
| As the LET of radiation increases the ability to produce biologic damage | increases |
| Protraction | Dose delivered continuously as a low dose rate |
| Fractionation | A high dose rate is maintained but is not continuous usually daily intervals occur between high dose therapy |
| Biologic effects affecting radio-sensitivity | Oxygen effect, age, gender, recovery, and chemical agents |
| OER | This states that the presence or absence of oxygen effects tissue sensitivity to radiation |
| True | Tissues that is highly oxygenated (aerobic) is more sensitive than tissue low in oxygen (hypoxia) or without oxygen (anoxia) |
| Sensitivity Prior to birth | most sensitive |
| Sensitivity when Mature | Least sensitive |
| Sensitivity when old age | Slightly more sensitive than when mature |
| Who is more radioresistant | Females by 5 to 10 % |
| Radiosensitizers | Chemicals agents that cause the cells, tissues, or organs to be more radiosensitive |
| Radioprotectors | Chemicals agents that cause the biologic specimen to be resistant to radiation |
| Hormesis | A little radiation is good for you |
| This has an application of radiology, design of therapeutic plans and provides information on low dose exposures | Dose response relationship which is a graphic representation of the relationship between radiation dose and the magnitude of the absorbed response |
| A linear response and linear threshold are both what on a chart | Straight |
| Non-linear non-threshold and non –linear threshold are both what on chart | Slightly curving |
| Threshold | A level that is reached below which no effects are observed |
| Non-threshold | Any amount of radiation may cause a response |
| Diagnostic x- ray which | A linear non-threshold dose response relationship |
| These also follow a linear non-threshold | radiation induced cancer, leukemia and genetic effects |
| Sigmoid (s type) dose | A non- linear threshold radiation dose relationship primarily applies to high dose effects such as those seen in radiation therapy |
| Charteristics of a sigmoid type dose response curve | Usually a threshold , partial recovery from lower dose, decreased response at lower dose called the rate effect a plateau and possibly a turning downward at the highest dose curve exhibits non-9sochastic or certainty effect |
| Linear quadratic dose response curve | Believed to be a more accurate estimate of the risk associated with low level radiation, a more accurate reflection of stochastic and genetic effects at low dose levels from low LET radiations |
| Stochastic (statistical) effects | Random in nature, probability or frequency of the biologic response to radiation as a function of the radiation dose examples: hereditary effects and carcinogenesis |
| Nonstochasic (deterministic) effects | This is a certainty. Biologic effects of ionizing radiation that demonstrates the existence of a threshold example: cataracts, non-malignant damage to skin, blood deficiencies, and impairment to fertility |
| Chromosome | Tiny rod shaped structure that contains DNA |
| DNA | The essential ingredient in chromosomes and the carrier of the genetic code for reproduction and cell activity contains all hereditary information ,double helix structure, nitrogen containing , organic bases, sugar phosphate backbone and a nucleitide base |
| Organic bases of DNA are | Adenine, quinine, cytosine, and thymine |
| Gene | The basic unit of heredity |
| alleles | Gene pairs (homozygous or heterozygous) |
| Karyotyping | A way of identifying or mapping out genes, way of detecting gene mutations |
| In vitro | Irradiation outside of the body or cell in a petrie dish |
| In vivo | Irradiation within the body or cell |
| Irritation of macromolecules in a solution in vitro causes what | main chain scission , crosslinking, and point lesions |
| Main chain scission | The Breaking of the backbone of a long chain macromolecule, reduction of a long single macromolecule into smaller macromolecule, viscosity decreases (thins) |
| Crosslinking | Macromolecules have small spurlike side structures extending off the main chain, spurs attach to other macromolecules or other segments of the same molecule, viscosity increases (thickens) |
| Point lesions | Disruption of the chemical bonds with in the molecule late radiation effects observed at the whole body level these are not detectable but can cause malfunction within the cell |
| Measures of viscosity determine what | The degree of main chain scission |
| Metabolism consists of | catabolism(reduction of nutrient molecules of energy) and anabolism(the production of large molecules for form and function) |
| This is the most radiosentitive molecule | DNA |
| Half as much DNA is present in G1 than in | G2 |
| Somatic mutations | Have genetic consequences for that individual only |
| Genetic mutations | Has effect on reproductive organs or gamates one or both parents it will possibly be expressed in future generation |
| Radiation effects are not radio unique this means | will make this happen but it will make it more likely to happen or will happen sooner |
| Most mutations are | undesirable |
| Mutative effects are probably | Cumulative |
| Target theory | There are more than one sensitive key molecules in the cell if these are damaged the cell will not be able to continue to function |
| Key target molecule is | DNA |
| If radiation interacts with the target molecule it is called what | A hit |
| Indirect hit effect | Ionization of a noncritical molecule transfer of energy to target molecule production of ions which are poisonous cell is damaged or indirectly destroyed |
| Radiolysis of water | Disassociation of molecules by radiation means by which indirect hit may cause damage formation of free radicals |
| Lethal effects of radiation are determined by | Observing cell survival not cell death |
| Cell survival curve | A description of the relationship between dose and proportion of surviving cells |
| 2 models for cell survival | Single target single hit and multi-target single hit |
| Single target single hit | Applies to biologic targets such as enzymes, virus’s and simple cells such as bacteria |
| Poission distribution | D37 the measure of the radio-sensitivity of biologic tissue |
| D0 means | Mean lethal dose equal to D37 in linear portion of graph and represents the dose that would result in one hit per target in the straight-line portion of the graph if not radiation were wasted |
| Large D0 means | Radio-resistant cells |
| Small D0 means | Radio-sensitive cells |
| D37 mean | When radiation dose reaches a level that is sufficient to kill 63% of the cells (37%) survive |
| If there were no wasted hits (uniform interaction) D37 would be sufficient to kill what percentage of cells | 100% |
| Multitarget single hit | Human cell has two targets which must be inactivated to kill the cell |
| DQ | Threshold dose related to recoverability of a cell from a sub-lethal exposure or dose |
| Cell cycle effects mitosis | Cell cycle time average time from one mitosis to another most cells take 24 hours |
| Age response function | Pattern of change in radio-sensitivity as a function of phase in the cell cycle |
| Phase radio-sensitivity | 1. M phase 2. G1 S transition 3. Late s phase is the most radio-resistant |
Created by:
hseratt
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