Feb 24- Prescribing Radiographs FINAL Flashcards
With regard to units, we talked about three important ones, represented by D,H and E. what are they?
D= Radiation - absorbed dose. The amount of energy absorbed from the radiation beam. measured in Gray
H = Equivalent dose. Allows compasisons to be made between different types of radiation. measured in sieverts
E = Effective dose. How sensitive a certain part of the body is to a dose. measured in sieverts.
What is the approx average annual background radiation dose to a person livin gin the US?
2-3 mSv
what is the equivalent background radiation of a panoramic and a periapical or bitewing?
panoramic - approx 2 days worth of background radiation dose. 1/1million chance of fatal cancer
periapical - apprix 1 day. 0.5 in a million of fatal cancer
What is the approx and relative level of yearly exposure for dental x rays?
0.0005 msv. this is less than basically everything else, inlcuding medical x rays (chest 0.1 , mammogram 0.4 , spine, CT - 2), natural radiation 2/yr , and of course accidents like chernobyl 350
so if so little radiation comes from dental x rays, why worry about it?
- additional radiation burden to the pateint
- Every exposure carries with it the possibility of a stochastic effect (damaging effect)
- an enormous number of dental radiographs every year can add up for a fairly substantial collective dose.
what is the occupational and the non occupational dose limit?
occupational - 50 mSv annual effective dose limit and no more than 100 in a 5 yr period
non occupational - 1 mSv annual dose limit and if higher, not to exceed an annual average of 1 msv over 5 yrs.
in reality, our dose as a profession is much lower than the allowed amount, it’s about 0.2 msv or 0.4 % of the limit.
What are some things we can do to reduce the dose for patients?
use digital or f speed film, rectangular collimator, correct expsure time, correct technique - use holders, limit the number of exposures for what is diagnositc, lead apron and thyroid collar.
Where do we get the guidelines for radiographs?
in 1983 the FDA and ADA produced guidelines, they were updated in 2012. they are a resource, not a standard of care. We should make judgements based on each individual patient.
what’s the main goal of these guidelines?
to reduce the amount of exposure to patients without reducing the quality of care. making ppl responisble for the allocation of health care resources, individualized prescribing
According the the guidelines, radiograohs should only be prescribed when there is: (3)
a historical finding and/or a positive clinical sign or symptom, and or a high probability of obtaining clinically useful information.
what things should be doing before taking a radiograph?
a thorough clinical exam
medical history
signs and symptoms
dental history
environmental factors
should we use radiohraphs as a screening tool?
no. there woudl be a large risk if millions of ppl recieved unproductive radiographs as screening. the only exception to this is bitewing radiography because they show areas of the tooth that we can’t see or feel very well.
should we take radiographs for fear of possible law suits?
no. you are more likely to get sued for taking too many rather than not enough. Take then when there is an expectaiton that the diagnostic yield will effect patient care. use clinical judgement
before taking a radiograph, what are three quesitons you should ask yourself?
why is this being taken
what do you expect to derive
how to derive and interpret
should we be taking radiographs of ladies with buns in their ovens?
Limit radiographic exams during pregnancy to cases with a specific diagnositc indication. so only take them if you need to. postone elective radiographs until the baby is born. always use a lead apron and thyroid collar.
what are the relative radiographic exam resolutions ?
what is the relative effective doses of diff types of images?
What are the ADA guidelines regarding the frequency of taking different types of radiographs?
