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NE 490 Exam #2
Question | Answer |
---|---|
Where is necrosis found in the tumor during hypoxic cell death? | In the center |
Place the cell phases from most radiosensitive to least radiosensitive | M>G2>G1>Early S>Late S |
Which cell oxygen condition results in greatest cell KILLING? | Aerated (oxygen KILLS cells) |
What is the Do in a single-target, single-hit model? | Dose required to kill population down to 37% |
How can you synchronize the cell cycles? | Mitotic Shakeoff (round up and de attach from the monolayer) Hydroxyura (kills cells in S phase, stops after G1) Single large dose |
How does fractionation help with cell repair? | Giving time between doses give cells more time to repair and produce, only true for low LET (gammas), not true for neutrons |
What is more damaging, 1 Gy of protons or 1 Gy of gammas? | protons (HIGH LET) |
What is the radiation damage associated with the shoulder of cell survival curves? | Sublethal damage |
What does a high shoulder mean? What would the n value be? | High shoulder means more radio resistant cells (bacteria), more time to repair in between doses, n would be high (3-5 range) |
The quadratic portion of linear-quad model is physically explained by chromosomal aberrations being result of separate breaks from two different particles | TRUE |
When is OER absent? | For high LET particles, such as alphas and protons |
What are the three genes that are associated with carcinogenesis? | oncogenes (deal with cell suicide, cell will keep producing), tumor suppressor genes, DNA repair genes |
What cell phase is the most sensitive? Less sensitive? Where is DNA replicated? | M, Late S, S |
What are checkpoint genes? | Genes that monitor cell and check for damage |
4 Rs of Radiotherapy? | Repair, repopulation, reassortment, reoxygenation |
What the symptoms of ARS? | 1 Gy- nausea, vomiting, bleeding, infection 5 Gy- same, but for whole population 10 Gy- organ failure 50 Gy-death in a couple days |
What would you see in a dose rate graph with high dose rate? | No shoulder, steep slope |
What would you see in a dose rate graph with low dose rate? | More of an shoulder, more time for the cells to repair |
What is LD5060? What is it for humans? | Dose to kill half of the population in 60 days, around 5 Gy for humans |
What is the difference between stochastic and deterministic damage? | Stochastic: doesn't have threshold, probability increases with dose, ex: cancer Deterministic: has threshold, severity increases with dose, ex: cataracts |
Which is more radiosensitive, bacteria or human cells? | Human cells are more radiosensitive than bacteria since human cells has DNA, more susceptible to cell damage |
What is the different types of radiation damage for cells? | Sublethal: repaired within hours, interact to create lethal Potentially lethal: dose is usually lethal unless there is something that is done to modify the environment Lethal: cell death |
What is hematopoietic syndrome? | happens around 2.4-5 Gy, deficiency within white blood cells, lymphocytes and platelets, and immunodeficiency peak at 30 days, continue to 60 days can form infection due to shortage of white blood cells |
What can be done to estimate dose after radiation accident? | Time from vomiting, number of lymphocytes (lost after dose),look for chromosome aberations |