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22 Cards in this Set
- Front
- Back
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what is radiation absorbed dose?
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measures of amount of energy absorbed from the radiation per unit mass of tissue
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what is equivalent dose?
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takes account of effectiveness of types of radiation (Q factor) into measuring effect of radiation.
Equivalent Dose = RAD x Q |
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What is effective dose?
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Sensitivity of tissues to radiation is taken into account. eg. gonad is more sensityve to a finger
Effective Dose = Equivalent dose x weighting factor |
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What is the unit for equivalent dose?
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Sv
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What is the unit of effective dose?
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man-Sv
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What are biological effects of X-rays?
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can cause cancer, leukemia, mutation, carcinoma, congenital defects
some are cumulative |
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Classify the biological effects of X ray
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Somatic deterministic effect
Somatic stochastic effect Genetic stochastic effect |
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Explain somatic deterministic effect and give example
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radiation dosage must exceed certain level to cause harm
eg. skin reddening |
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Explain somatic stochastic effect and give example
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there is no set radiation threshold. Any exposure can has a chance of causing damage. eg. cancer or leukemia
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Explain genetic stochastic effect and give example
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just like somatic stochastic effect but involving gonads. congenital abnormality.
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Classify how x-rays can cause damage
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direct and indirect effect
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What is the direct effect of X ray damage?
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DNA damage
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What is the indirect effect of X ray damage?
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H20 -> Free radical H2 and H2O2
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What is the max permissive dose for the occupationally exposed?
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1mSv/yr
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What is the max permissive dose for the general public?
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1 mSv/yr
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What is the max permissive dose for a pregnant woman?
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less than 1 mSv/9months
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What is ALARA and why is it significant in radiology?
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As Low As Reasonably Achievable
Due to Stochastic effect of X ray, any amount of X-ray is considered harmful. Hence Xray must be only used when necessary |
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How is kVp related to X-ray damage to tissues?
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Low-energy rays are absorbed by patient
Hight kVp produce less low energy rays Use Highest kVp consistent with good image and situation |
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What equipments are available to minimize damage of x ray?
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x-ray beam collimation
Filtration (Al at least 2.5mm) Use long cone Electronic exposure timers Film holding device F speed film Lead aprons and thyroid collar |
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As an operator what can u do to minimize x-ray damage to the patient?
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Do not (prevent) take multiple X rays
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Staff is subject to what kind of radiation damage?
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Primary beam
Scattered Leakage |
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What can operators do to prevent x ray damage?
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Position (out of primary beam)
Distance (minimum 6 feet) Shielding (barriers walls) |
