Re: a dose query

[Peter.Thomas@health.gov.au]

Mark,



You wrote ...







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Subject:        a dose query



This is just a little query: 

What is the (whole body) effective dose (in microsieverts) from a typical 

dental xray, (eg, bitewing) giving something like 3 mGy absorbed dose in 

air 

at the skin surface? 

Is this even a sensible question to ask? 

Mark Sonter 



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According to Williamson's NRL Report from New Zealand (1990) the mean dose 

to air

for a 60-70 kV bitewing was 4.0 mGy.  This then gives an entrance skin 

dose of

4.7 mGy and highest doses of 0.42 mGy, 0.27 mGy and 0.33 mGy to the

sinuses, salivary glands and pharynx respectively.  The effective dose 

amounts

to about 9 microSv and is dominated by the contribution from the salivary 

glands

i.e. 0.27 mGy x 0.025.  Thyroid dose is 21 microGy.  Williamson's organ 

doses

come from measurements using LiF TLD chips on a Rando phantom with

normalisation to entrance skin dose.



There probably is more recent data but I doubt if there is much different 

beyond the

value for the entrance skin dose/air kerma.



Peter Thomas

Medical Physics Section

ARPANSA



The above represents my own thoughts and are not necessarily those of the 

Agency



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