Answer to Question #10779 Submitted to "Ask the Experts"

Category: Medical and Dental Patient Issues — Worker Issues

The following question was answered by an expert in the appropriate field:

Q

I am a dental hygienist asking if taking a bitewing dental x ray using digital phosphor plates (63 kVp, 08 mA with exposure time of 0.125 seconds) is a lot of radiation exposure to a patient? Usually four bitewings (BWs) and two periapical (PA) radiographs are taken once a year. Is it enough to cause cancer? What about 63 kVp, 08 mA with exposure time of 0.32 seconds? Patients are asking what amounts they are exposed to. We explain to our patients about exposures but I would like to go more in-depth with them.

Thank you so much for your time. This will ease a lot of patients' minds.

A

The short answer is that no, the amount of radiation in digital bitewing and periapical radiographs is not a lot of radiation; and, at these low doses, it is extremely unlikely that cancer will occur as a result of the exposures. There are several ways to evaluate exposure to radiation in these small doses.

First of all, it is generally accepted that radiation physicists as a group, do not fully understand the body’s reactions to what is termed "low-dose radiation" which all routine intraoral and panoramic radiography falls into. Just how much radiation is the patient in your practice being exposed to? About 1 µSv per exposure, or about 6 µSv for four BWs and two PAs, depending on which PAs you take. We are all exposed to background ionizing radiation 24 hours a day, seven days a week. The average person in the United States receives about 8 µSv of radiation every day, so this dose is less than one day’s radiation dose. A typical panoramic radiograph is ~16 µSv, or roughly two days of background radiation equivalence. A digital FMX (full-mouth x ray) (including photostimulable phosphor plates) using rectangular collimation will yield about 38 µSv of radiation dose; an FMX with digital receptors and standard round cones yields about 160 µSv; and, finally, an FMX using D-speed film and round collimation yields about 388 µSv. These numbers are from White & Pharoah's 6th Edition of Oral Radiology: Principles & Interpretation, which is the leading textbook used in dental schools today.

Secondly, the best way to limit radiation exposure is simply not to order and expose radiographs unless there is a reasonable chance that the information obtained from the radiographs will affect treatment outcomes. That is why today, the recommendation is for absolutely zero "routine" radiographs and that radiographs only be taken after a clinical examination and when there is an expectation that the radiographs will yield diagnostically helpful information.

I hope this information is helpful!!

Jeffery B. Price, DDS, MS
Associate Professor of Oral Radiology

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 18 September 2013. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.