radiation risks Flashcards
- Have a threshold
- severity is proportional to
the dose
-erythema
-xerostomia
-cataract
-fertility
-alopecia
-fetal development
deterministic risk/effect
- Have no dose threshold
- Probability of occurrence
is proportional to dose - Severity of effects does not
depend on dose
stoachastic effect
-genetic mutations cause
malignancy= ___cells
to somatic cells
genetic mutations cause heritable
effects= ___cells
to germ cells
more you apply dose, the greater the risk
(risk at every dose)
stochastic effect
below threshold wont see affect
deterministic
That amount of radiation which in the light of
present knowledge will not produce any
serious, harmful, or deleterious effects on the
individual receiving it.
max permissible dose
max permissible dose
occupational limits:
non-occupational limits:
occupational limits: 5.0rem/year (5,000 mrem) 50 mSv
non-occupational limits:
0.5 rem/year (500 mrem) 5 mSv
average annual effective dose of ionizing radiation (mSv) to a member of US population
x-ray diagnosis:
nuclear medicine:
natural plus artifical total:
x-ray diagnosis: 0.39
nuclear medicine: 0.14
natural plus artifical total: 3.60
medical xrays and nuclear medicine is only ____of radiation exposure
1/6
source of radiation exposure is ___times greater with medical and nuclear medicine?????
6 times greater
these patients are at risk
pediatric patients
this rate of growth puts tissues at greatest level of radiosensitivity (children)
rate of cellular and organ growth
greater life expectancy puts children at ___times greater risk of being afflicted with radiation induced cancer
2-6 times
females ____ years old are 5 to 6 times more likely to develop fatal cancer than 50 year old
males <10 yo are ___times
females <10 years old
males 4 to 5 times
20 yo female are ___times than 50
30 yo female __times
3.5
3
Cancer risks __ with increasing
age
decrease
effective dose for FMX d-speed round coll
usv 388
days background radiation- 46
[1 day of background radiation ~8.5 uSv]
efffective dose for dental exam procedure
1.5 dose (mrem)
these cancers have the highest risk from dental radiographic exposure
leukemia and thyroid
artifical/manmade radiation sources - 2%:
- consumer products (TV, wristwatch, computers)
- airport scanners
- nuclear fuel cycle
- weapons production
- fall-out from atomic weapons
1959, dental radiation dose was ___rad/second with 8 incih distance 10mA, 65 kv
one periapical exposure averaged 2 seconds, so this equates to
1 rad/second
2 rads/exposure
in 1959,
1,250/2 = ____ exposures delivers the TED
620 exposures delivers the TED in 1959
in 2024, an 8 inch focal distance at 7mAs and 0.2s =
1,250/1.4 = ___ exposures delivers the TED
1.4 mAs/ exposure
893 exposures
in 2024, Using properties of the Inverse Square Law,
the dose is decreased ~37 % if the focal distance is
doubled to 16”
and at 16” focal distance; __+___ exposures delivers
the TED or, __exposures delivers the TED
893 + 330
1m223 exposures delivers the TED
studies show risk for congenital defects at
50 mSv or less
OMR imaging fetal dose
0.01 mGy; 10uGy
at absorbed doses of 0 to 50 mGy, there is ___risk of fetal death, malformation, growth retardation or impairment of mental facility
NO
stochastic risk estimates for pregnancy
absorbed dose to the coceptus of ~25 mGy (25,000 uGy) does what
double natural childhood cancer rate
dental imaging exams of pregnant women should/should not be restricted if clinically indicated
should not
Radiographs of pregnant patients as part of any new
patient or recall exam must be :
postponed until postpartum.
If urgent care dental treatment is required during
pregnancy, radiographs may be :
necessary as the
standard of care to treat and diagnose a condition that
threatens the health of the mother and the unborn
child.
The clinician must assure that the primary beam
is not directed toward the child-bearing area.
risk of death for FMS exam
2.5 per 1,000,000
