Re: Assesing X-ray dose from 60KVp dental X-ray machine

[andrew_mcewan@nrl.moh.govt.nz]

Sunil Nair wrote
___________________________________
Our dentist is using a 60Kvp X-ray machine. I have been issuing TLD(based
on CaSO4:Dy) for his personal monitoring but it always report zero dose. I
just want to make sure that the TLD reading is right. I am also a bit
worried about the dose anybody else may receive who are in the vicinity
but not behind the "gun". The doctor usually stand behind the X-ray "gun"
so the TLD might be right after all.  I would like to know how much dose
it produces in the vicinity (say, after scattering from the patient) and
how personal monitoring is done for the operating staff of such an energy
machine else where.

 ___________________________________
Our measurements show a person standing about 2 metres behind the back of the
patient's head will be exposed to an effective dose of about 200 microsieverts
per year (0.2 mSv/y) based on a workload of 50 intraoral films a week.  If the
TLD wearing period is 4 weeks there might be less than 0.02 mSv recorded,
depending on how far back the dentist stands.  Dose could be below the reporting
level of the TLDs.

Andrew McEwan
_______________________
Andrew C McEwan PhD
National Radiation Laboratory
PO Box 25-099
Christchurch, New Zealand

Ph 64 3 366 5059
Fax 64 3 366 1156
Andrew_McEwan@nrl.moh.govt.nz



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