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20 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the threshold radiation for possible cataract?
what is the latent period by dosage |
200 rads of acute exposure
250-650 rads - 8 years, stationary cataract 650-1150 rads - 4 years, cataract can get progressively worse |
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What is the difference between a senile cataract and a radiation induced one?
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Radiation cataract starts in middle and spreads out like a do-nut, with a hole in the middle and senile is all over.
what is unique about this ill effect? |
only one that is distinguishable as definitely coming from radiation
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What are dose descriptors?
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An attempt to determine the health effects of radiation on the population
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What is dose equivalent?
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Absorbed dose times a quality factor - Q
Q for X and gamma is 1, neutrons, alpha is 20 If absorbed dose is in rads the dose equivalent is in rem If the absorbed dose is in Gray, the dose equivalent is in Sievert |
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What is an effective dose?
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The weighted sum of the dose equivalent for each body tissue.
Attempts to account for the different radiosensitivities of all tissues of the body For example gonads is .20 while bone surface is .01 All tissues combined sums up to 1.0 |
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What is GSD (Genetically Significant Dose)?
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An index of the presumed genetic impact on the whole population
The equivalent dosage to the gonads weighted for age and sex distribution of the exposed population An attempt to average the effect on the whole population factoring in people who will not bear children It is very age and sex dependent |
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What is Collective Effective Dose?
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Sum of the product of the effective dose and the number of persons exposed
Per person dose from diagnostic procedures is about 130 mrem Not an even distribution based on age as older people with increased health problems have more procedures done |
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What are the 3 areas that contribute to background radiation?
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1. Cosmic-charged particles & photons from space
2. Earth's Crust-soil & rocks, uranium>radon 3. Internal - food and water, potassium 40 is biggest factor which one is the biggest factor? |
radon from uranium, specifically the daughter of radon that forms radioactive breathable particulate
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What makes up the largest percentage of man-made radiation?
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Diagnostic X-rays and NM procedures
name some other sources of man-made radiation? |
CRT's, nuclear fuel cycle, radioactive waste, air travel, fallout from weapons testing, consumer products
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What is the overall average annual dose from background radiation?
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360 mrem
what is the biggest contributor to background radiation? |
55% is radon, 200 mrem/yr
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What is the GSD for diagnostic imaging annually and how does it compare to the genetic doubling dose?
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GSD for diagnostic radiology is 30 mrem/yr and the genetic doubling dose is 100 or 156 mrem
what is GSD? |
Genetically Significant Dose
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What is the minimum dosage to consider a therapeutic abortion?
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10 rads or more, even then it is not advisable
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Each year _________nuclear medicine procedures are performed in the US of which only ______are therapeutic.
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Each year 10-12 million nuclear medicine procedures are performed in the US of which only 60,000 are therapeutic.
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In nuclear medicine what are the 3 areas of risk assessment and their implications?
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1. Total body dose -risk of leukemia
2. Critical organ dosage - varies with tissue type( may not be target organ) 3. Gonadal dose- genetic hazard |
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What is dosimetry and what does it depend on? (3 factors)
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dose measurement:
1. distribution of the radiopharmaceutical and its uptake in critical organs. 2. Inhomogeneous distribution even within critical organ 3. Biological half-life of the nuclide, which varies with pt's age and condition |
DIB
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What is the average dose equivalent to US population from NM procedures?
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14 mrem/yr
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What is the danger in pediatric exposure as well as to breast feeding women and in utero after 10th week?
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children with developing thyroid gland as this is very radiosensitive.
what is the most dangerous isotope in this regard? |
I-131
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Mutations is a stochastic or non-stochastic event?
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Stochastic, any amount of radiation can potentially cause a mutation
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What is a teratogen?
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an agent which causes birth defects
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Effects on the embryo or fetus are _______ effects (along with cancer)
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Effects on the embryo or fetus are somatic effects (along with cancer)
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