Lead Shield Dilemma

Please set us straight. Our office recently purchased a new digital panoramic machine. It can isolate any given area and take "bite wings" if needed as well.

Oct 16th, 2014

BY DIANNE GLASSCOE WATTERSON, RDH, BS, MBA

Dear Dianne,

Please set us straight. Our office recently purchased a new digital panoramic machine. It can isolate any given area and take "bite wings" if needed as well.

We had our in-office introductory training with the company training rep, and he said that using the lead shield is not necessary. He told us that the radiation output is so minute that shielding is not needed. The office as a whole is not comfortable taking digital radiographs without a lead apron. The doctor, however, has instructed us not to use an apron on the patients and says it is not "damaging radiation." I cringed when I saw a 16 year old get a panorex without the apron. For certain, I would put a lead apron on my family members, so why not all our patients?

We do take the "sensor" digital x-rays with an apron.

Does each digital company have their own criteria? What is the stance on lead aprons with ADA? Who are we to listen to? Are there any guidelines that are clear and supported by reliable evidence? I am so tired of the grey areas of regulation and varied interpretation in dentistry.

One solution we have explored is having a notice posted in our X-ray area that states something like, "Lead apron is no longer necessary. However, if you request added protection, we will gladly provide you with one." The thing is that we are not convinced that the lead apron is not needed.

Why does he care if we want to use a lead apron? And if it's so safe, why do we have to leave the room to make the exposure?

Many thanks and I have enjoyed 20 years of reading your articles!

California RDH

Dear California,

Digital technology has certainly improved radiographic image quality over the past few years, and I'm glad to hear that your boss has invested in a digital panoramic unit. Some of the images I have seen in client offices are nothing short of amazing. The variety of image tools increases the clinician's ability to visualize areas of concern as never before.

While digital radiography is known to use lower amounts of radiation than film-based models, radiation is still being generated. We also know that radiation is accumulative over time and with exposures. The radiation dose you received 10 years ago when you had that CT scan remains with you the rest of your life. Every subsequent exposure to radiation adds to that accumulated amount. Every precaution should be taken to ensure that radiation exposure is "as low as reasonably achievable," known as the ALARA principle. Most dental professionals feel that a leaded apron minimizes exposure to the abdomen and should be used when any dental radiograph is taken. Also, a leaded thyroid collar can protect the thyroid from radiation, and should also be used whenever possible. The use of a leaded thyroid collar is recommended for women of childbearing age, pregnant women, and children.

Table 1

Item Dose of Radiation in Millisieverts (mSv)

Banana

0.00001 mSv

Dental X-ray

0.005 mSv

Living within 50 miles of a nuclear power plant

0.01 (per year) mSv

A flight from NewYork to Los Angeles

0.04 mSv

Smoking 1 ½ packs of cigarettes

0.08 mSv

Living at sea level

0.25 (per year) mSv

Mammogram

0.3 mSv

Abdominal CT scan

14 mSv

Table 2

Digital pan + 4 BWS

27 Sv

Digital FMX

60 Sv

Film FMX

75 - 180 Sv

Digital FMX + Digital pan

74 Sv

Film pan + Film FMX

94 - 199 Sv

I consulted a number of resources to get reliable information concerning radiation dosage and the need for lead shielding. Kyle Steck, a regional manager with Henry Schein, Inc., provided some useful information (see Table 1 for interesting information on radiation dosing).

According to the World Nuclear Association, annual exposure to 100 mSv or greater carries a measurable, though small, increase in cancer risk. Below that level, it's believed that your body's cells are able to heal themselves from radiation. Table 2 shows dental radiographs measured in microsieverts. Microsieverts are 1000 times smaller than millisieverts. Of course, a millisievert is 1/1000th of a sievert.

Many states have their own rules concerning shielding. For example, in a publication titled Radiation Safety In Dental Practice that was published in December 2013 by the California Dental Association, it is stated: "Lead-impregnated leather or vinyl aprons must be used to cover the reproductive organs of all patients who undergo dental X-ray examinations" (www.cda.org/Portals/0/pdfs/practice_support/radiation_safety_in_dental_practice.pdf).

The National Council on Radiation Protection & Measurements (NCRP) published a guideline for radiation protection in dentistry in 2003 titled "NCRP Report No. 145: New Dental X-ray Guidelines: Their Potential Impact on Your Dental Practice." This report stirred considerable controversy with this statement: "The use of leaded aprons on patients shall not be required if all other recommendations in this report are rigorously followed."

This statement came from the ADA: "The amount of scattered radiation striking the patient's abdomen during a properly conducted radiographic examination is negligible. The thyroid gland is more susceptible to radiation exposure during dental radiographic exams given its anatomic position, particularly in children. Protective thyroid collars and collimation substantially reduce radiation exposure to the thyroid during dental radiographic procedures. Because every precaution should be taken to minimize radiation exposure, protective thyroid collars should be used whenever possible. If all the [NCRP] recommendations for limiting radiation exposure are put into practice, the gonadal radiation dose will not be significantly affected by use of abdominal shielding. Therefore, use of abdominal shielding may not be necessary" (www.ada.org/~/media/ADA/Member%20Center/FIles/Dental_Radiographic_Examinations_2012.ashx).

What are the NCRP recommendations to which this article refers?

• Thyroid collars should not be used on extraoral radiography (panoramic and cephalometric)

• All intraoral X-ray head collimators shall be rectangular, not circular, to minimize stray radiation.

• For film X-rays, the film speed shall be "E" or faster. D film shall no longer be used. Since Kodak no longer makes E speed film, this will mean going to F-speed or using another manufacturer's film.

• High-speed (400 or greater) rare-earth intensifying screens shall be used in extraoral films and digital systems shall employ a similar equivalent.

• For all new construction, shielding design will need to be provided by a qualified expert. Lead need not be used if proper thickness of gypsum board is used for the walls.

• Dentists must examine their patients before ordering or prescribing X-rays.

• Rigid dark room requirements, documentation and daily developer chemistry evaluation, and a quality assurance protocol manual will be required.

All dental professionals need to be aware of their particular state guidelines. For the California reader who addressed the question above, California mandates the use of the lead shield, although many experts today do not feel the use of the lead shield is necessary. However, we have to take into consideration the opinions and beliefs of our patients. Some patients would feel unsafe without the lead shield. The ADA statement uses the phrase "may not be needed," which leaves me wondering. As long as the lead shield doesn't block or distort the image and it makes the patient feel safe, it does not seem prudent to abandon lead shield usage. The last thing we need is for patients to leave our offices wondering if they have been harmed, and even worse, having dental professionals wondering if they have caused harm.

All the best,

Dianne


DIANNE GLASSCOE WATTERSON, RDH, BS, MBA, is a professional speaker, writer, and consultant to dental practices across the United States. Dianne's new book, "The Consummate Dental Hygienist: Solutions for Challenging Workplace Issues," is now available on her website. To contact her for speaking or consulting, call (301) 874-5240 or email dglasscoe@northstate.net. Visit her website at www.professionaldentalmgmt.com.

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