RBS EXAM 3 2023/2024

RBS EXAM 3 2023/2024 Reoxygenation - CORRECT ANSWER-Tumors cells grow more rapidly when in close proximity to a blood supply. Three stages of fetal development - CORRECT ANSWER-•Pre-implantation •Major organogenesis •Fetal (growth) stage when is the preimplantation stage - CORRECT ANSWER-conception to day 10 when is major organogenesis stage - CORRECT ANSWER-week 6 to post conception When dose fetal growth stage occur - CORRECT ANSWERRadiation effect on embryo/fetus - CORRECT ANSWER-Lethality congenital abnormality at birth long term/latent effects not visible at birth maximum permissible dose for an entire gestation period - CORRECT ANSWER-0.5 msv what group is in charge of doing follow up studies on groups exposed to radiation - CORRECT ANSWER-BEIR biological effect of ionizing most radiosensitive time in development of a fetus is _______ - CORRECT ANSWERweek 2-6, first trimester most radioresistant time in development of a fetus - CORRECT ANSWER-2nd and 3rd trimester Late effects of radiation - CORRECT ANSWER-•seen from low to high doses of radiation •Somatic effects occur •Genetic effects occur •increases with dose, dose rate and LET what are stochastic effects? - CORRECT ANSWER-No threshold. As dose increases, probability of occurrence increases but the severity does not. Think about cancer risk with radiation what does the NRC do - CORRECT ANSWER-they make the laws for protection of patients and health care workers NCRP (National Council on Radiation Protection & Measurements) - CORRECT ANSWER-no longer recommends specific controls for occupationally exposed woman until a pregnancy is declared. what 2 things can happen if cellular damage ocurrs - CORRECT ANSWER-- may prevent cells survival or reproducability - may result in a viable cell that has suffered a change or mutation What is the threshold dose - CORRECT ANSWER-In general most organs and tissues are not effected by loss of a few cells But at some level of dose the probability will increase rapidly Nonstochastic effects - CORRECT ANSWER-Somatic effects that have a threshold and increase in severity with increasing absorbed dose. stochastic effects - CORRECT ANSWER-Probability or frequency of the biologic response to radiation as a function of radiation dose. Disease incidence increases proportionally with dose, and there is no dose threshold. what is the therapeutic index? - CORRECT ANSWER-the percentage of tumor control that can be achieved for a given level of normal tissue damage Cause of mutated cells - CORRECT ANSWER-Carcinogens and hereditary effects Somatic cells that were exposed radiation...cx increases with dose. Chromosome - CORRECT ANSWER-Carries all the information that specified a human *DNA* Mutation - CORRECT ANSWER-Any changes in chromosome their genes and DNA Is radiation a mutagenic agent - CORRECT ANSWER-Yes heritable effects of radiation - CORRECT ANSWER-Gene mutation chromosomal Changes multifactorial Doubling Dose Concept - CORRECT ANSWER--the radiation dose that causes the number of spontaneous mutations occuring in a given generation to increase two times their original number -1.56 Sv Radiation induction of mutations - CORRECT ANSWER-has no clear threshold; it is a stochastic effect similar to carcinogenesis. Does radiation dose produce new mutations - CORRECT ANSWER-No it just increases the frequency of mutation in each generation Deterministic effects of radiation - CORRECT ANSWER-•occur within days of radiation exposure •tissue damage Stochastic effects - CORRECT ANSWER-direct function of dose with the probablility of occurrence increasing with increased dose, ex. cancer, genetic mutations four R's of radiobiology - CORRECT ANSWER-Repair Regenerate Redistribution Reoxygenation Hypoxic cells are more ___________ to radiation - CORRECT ANSWER-resistant Dose fractionation is successful why? - CORRECT ANSWER-Allows cells to reoxygenate during treatment What does fractionation allow (effects do to 4Rs) - CORRECT ANSWER-•Fractionation allows normal tissues to repair sublethal damage and regenerate. •Fractions size is a key factor in determining late effects. •Dose rate effects the biological consequences. Two effects of radiation dose on dividing cells - CORRECT ANSWER-Delay in progression of cells in cell cycle surviving populations tend to be synchronized in resistance phase Slow growing tumor and normal tissues - CORRECT ANSWER-Lung and spinal cord Rapid growing tumor and normal tissue - CORRECT ANSWER-Skin intestines esophagus What happens to decreasing dose/ fraction in late responding tissue - CORRECT ANSWER-As dose/ fraction will increase the tolerance for late responding tissue decreases Redistribution - CORRECT ANSWER-Cells that survive a dose of radiation due to synchronization in the resistance phases. Reoxygenation - CORRECT ANSWER-Receive O2 from normal tissue as they repair making the tumor more susceptible to death b