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Rad Biology Unit 3
| Question | Answer |
|---|---|
| How is the extrapolation number found on a sigmoid dose curve? | N is found by extrapolatial segment of a sigmoidal dose survival curve to intercept at the ordinate axis |
| What two factors effect progrssion delay? | 1. The phase in which radiation occurs and 2. the radiation dose |
| Explain the effect that oxygen has on the survival of cell include relationship with LET, explain the extrapolation number, and problems that a rise in tissue in mixed oxygenation | The more oxygen the more radiosensitive; as LET increases OER decreases; ex# of cells cannot be related; a variety of mixed sensitivity that cant be overcome |
| Be able to Draw expoential curve then it explain it | Exponetial Curve Single-Hit: Single Target Model This suggest damage for radiation is not accumulating |
| Be able to Draw the sigmoidal curve and then explain it | Sigmoidal Curve Mutliple-Hit/Multiple Target Model This suggest radiation is accumulating damage |
| In intracellular reponse, radiation of differing LET will have what effect on the survival cellls | different effects |
| High LET = ____ ______ | more ionization |
| This refers to the capacity of the cell to reproduce | survival of the cells |
| If a cell can not reproduce then what happens | extinction |
| This is the survival relationship of any given quantity of radiation dose kills the same proportion of cells as every other quantity | exponential dose(all of nothing; survive or die) |
| The same number of cells die between 0-100R as will between____-____ | 700R-800R |
| cells obeying by an exponential dose is the survival reponse has___ critical targe governing reproductive capacity and __ critcal change to be made for the target to inactivate | 1: and single |
| What are the three parts to a sigmoidal curve | 1.a slight negative slpoe from theorigin through very low dose range 2.An inflection called the shoulder 3. An exponential survival response through the remaining higher dose range |
| This is the reponse relationship that more than a single critical change must be made before reproductive capacity falls | A sigmoidal dose |
| Cells demonstrating the sigmoidal dose curve must have ______ and these targets must_____ | more than one target; be inactivated |
| The amount of radiation necessary to destry targets governing cellular reproductive capacity | Radiation sensitivity |
| In cell populations that have more than one target, there is less damage to the reproductive capacity after exposure to radiation doses given in___ than from the same dose given in _____ | fractions; single exposures |
| Unless multi-targeted cells are killed by radiation, they are able to do what and what is likely to occur | recover from some or all the damage; full recovery of the cells is likely to occur because enough time will elapse between radiation |
| What is progression delay | When the cells are irriated, progression through the life cycle stops and resumes later |
| What is the most sensitive phase of a cell life cycle... what comes next | mitosis or M phase; G1-S transition |
| What is the most resistant phase of a cell life cycle | S phase |
| What makes cells sensitive to radiation | oxygen |
| The affect of sensitization is most profound with | lower LET |
| As LET is increased oxygenation males | less of a differnce |
| What is the oxygens role in indirect action | Reactions between free radicals and oxygen increase the probability that target molecules will be changed and lose function |
| This is the expression for degree of oxygens enhancement of radiation affects | oxygen enhancement ratio(OER) |
| How is OER determined | by measuring the radiation dose required to produce a specific effect under conditions of FULL OXYGENATION and the fullest possible HYPOXIA and expressing the result as a ratio |
| The OER for mammalian cells is between | 2 and 3 for x and gamma ray |
| What two things does the oxygen and survival curves show | hypoxic cells become resistant to radiation and a drop in extrapolation # which means less targets so less recovery is possible under hypoxia |
| What does "in vitro" mean? | test tube |
| Cells populations of varying sensitivity to radiation | mixed oxygenation |
| Most, if not all, ____ contain groups of severly hypoxic cells | cancer |
| Cancer cells are | radioresistant as compared to more senitive normal cells |
| How do you overcome the resistance of the cancer cells | try to increase the oxygen level of cancer and not healthy cells and use higher LET radiation to minimize the Oxygen effect |
| LET increases- OER ____ | decreases |
| Explain Recovery time | lesser effects will be produced by any given dose of radiation if the radiation is given slowly, over long periods of time than given rapidly |
| OER decreases as dose rate_____ | decreases |
| these may react differently when they are not independent entitles | in vivo cells |
| How do "in vivo" and "in vitro" cells relate | for the most part the experiments were the same;survivle comes however the expo# for in vivo was higher which tells that this cell repairs itself better when part of a tissue and not individuals in artifical medium |
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atesta0824
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