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Second Opinion: Radiation Minimization – “Are We There Yet?” by Dale A. Miles, BA, DDS, MS, FRCD(C)

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Radiation Minimization
- "Are We There Yet?"
by Dale A. Miles, BA, DDS, MS, FRCD(C)
Second opinions are common in health care, whether a doctor is sorting out a difficult case or a patient is not sure what to do next. In the context of our magazine, the first opinion will always belong to the reader. This feature will allow fellow dental professionals to share their opinions on various topics, providing you with a "second opinion." Perhaps some of these observations will change your mind, while others will solidify your position. In the end, our goal is to create discussion and debate to enrich our profession.
- Thomas Giacobbi, DDS, FAGD, Editorial Director, Dentaltown Magazine

If you've been on a long trip with kids you've probably heard the question many times - Are we there yet? It's easy to answer if you are driving the family car, not so easy in the dental practice when the patient asks you "Why do I need these X-rays?" or "Are these X-rays safe?" Hopefully this brief discussion of current concepts and guidelines, updated recently, jointly by the AAOMR and ADA, will give you the information necessary to take the final steps to minimize all of your patients' X-ray burden successfully and easily as well as answer their questions.

What Have We Done Well?

Manufacturers and clinicians have continued the move to faster image receptors. We've gone from D-speed film to F-speed film with conventional film-based imaging. Many offices have adopted PIDs (position indicating devices), largely because their staff members who take radiographs have been trained this way in dental schools and in dental auxiliary programs. The use of the PIDs with any type image receptor facilitates the correct placement of the receptor and greatly reduces retakes - a significant factor for increased patient dose. Every retake increases the X-radiation burden to the patient by 100 percent for that area.

Dental offices using conventional film are more routinely using the leaded aprons and thyroid collars for their film-based imaging procedures. With the new NCRP #145 report,1 dental offices that switch to become totally digital for their X-ray procedures do not actually have to use a leaded apron except on females who are pregnant or might be pregnant. Use of the leaded apron for procedures where the apron might interfere with the diagnostic information (panoramic and cone beam imaging) is unnecessary according to the new NCRP guidelines. However, if the patient asks for a leaded apron, one should be provided.

These current guidelines have both "should" and "shall" statements, and the "shall" statements are considered mandatory. Thus, the use of the thyroid collar on all children is mandatory, independent of the type of image receptor - conventional film, phosphor plates or solid-state detectors (sensors).

Only about 45 percent of North American dentists have adopted solid-state, digital imaging receptors. These clinicians and their offices should be commended for using fast image receptors.

Manufacturers have also helped the profession minimize radiation to the patient. We now have contemporary X-ray generators that are DC (direct current) with state-of-the-art timers to accurately match the very fast exposure times for solid-state detectors. And, of course, all of the companies who make or resell solid-state systems should be commended for helping the profession advance the radiation-minimization cause.

Institutionally, dental schools and dental auxiliary programs continue to adopt faster image receptors when economically feasible. Dental auxiliary schools teach long cone, rectangular collimation technique and rectangular collimation devices. Unfortunately no one is using them in their offices. After graduation, dentists, assistants and dental hygienists all abandon rectangular collimation. The main reason being, "I can't possibly hit the image receptor with a small rectangular beam of X-rays." Since this is a major way of minimizing radiation to all patients we will address this and describe simple and easy technology for the office to adopt.

What Can We Do Better?

It goes without saying that we should continue our move to the solid-state detector environment - digital sensors. And by this, I mean the direct capture receptors, not indirect capture devices like phosphor plate systems. There is a reason why only three to four percent of North American dentists have adopted phosphor plates. Although initially they seem like a great substitute, without a wire and an easier transition to film, dentists soon realize that phosphor plate systems not only require "care and feeding" but also do not give the dose reduction obtainable by solid-state detectors, wired or wireless.

Dentists should carefully examine and adopt the recommendations in the current NCRP report. The report contains guidelines for radiation protection in their dental offices (report #145). Dentists should also locate those companies that carry products to reduce the patients' X-ray burden. One such company is called HealthFirst (Mountlake Terrace, Washington). They carry a simple retrofit, rectangular collimator and personalized dosimeters that the patient can wear to quantify X-ray dose for every X-ray procedure received in the dental office. The company also provides promotional materials to help the dentist advertise low-dose practices and promote them to patients.

Almost all patients fear X-ray procedures, have been alarmed, been made more aware of potential problems through the media, or ask dentists and their staff members daily, "Why do I need these Xrays?" So, the dentist and his/her staff should be well-versed in the current guidelines published and re-published by the American Dental Association and the AAOMR (American Academy of Oral and Maxillofacial Radiology) on several occasions.2,3 I, in collaboration with Dr. Robert Langlais, published (2004) an abridged version4 of the entire set of guidelines shortly after they were released in 2003. Our "Cliff Notes" version can be downloaded for free from my website: www.learndigital. net. On the site there are other publications that would be helpful to assist dental offices in educating patients about the effects of dental Xrays and how their offices can take measures to reduce the burden and protect the patient.

In addition to education in these physical measures for reducing the patient's dose, the use of "Selection Criteria,"4 is important. This is examining and prescribing only those X-ray images that are necessary for the patient and for the dentist to make clinical decisions. These guidelines, too, have been published since 1987,2 republished over the years by the American Dental Association, taught in every dental school and dental auxiliary program in North America and yet have been largely ignored for the past 40 years. This is unacceptable. Unfortunately, the "non-adoption" by most dental offices falls into the category of what we have failed to do.

What Have We Failed to Do?

All in all, I believe that many dentists have done the best job of the health-care professions in reducing X-ray dose to the patient. However, we are not all adopting digital X-ray technology. We are not all using thyroid collars on children. Very few of us are actually using rectangular collimation despite being taught this technique for the past 40 years. And, almost none of us are practicing the principles of selection criteria - probably the single- biggest way to reduce the dental population's radiation burden.

By now many of you are probably telling yourself or realizing, "Boy, I really have failed to reduce my patients X-ray burden." So what can you do?

What Should We Do Next?

Before I became a radiologist, I was a dentist. Actually, I still am. Therefore, I like to see things in a concise, logical pattern so that I can quickly learn what needs to be done and take the necessary steps to incorporate it into my office protocol. Consequently, here's what we all should do next:
  1. Use selection criteria to determine, on an individual basis, the number, type and frequency of dental X-ray procedures needed for your patients.
  2. Go digital. Consider adopting solid-state detector technology, which produces up to 90 percent less radiation than conventional D-speed film.
  3. Read and adopt the guidelines published by the NCRP (report #145) and recommended by our own American Dental Association.
  4. Use a thyroid collar on all children except where it interferes with the diagnostic X-ray exam (panoramic and CBCT procedures).
  5. Adopt and use rectangular collimation.
  6. Consider using personalized dosimetry for patients concerned about X-radiation.

These suggestions can be fashioned into an office protocol that helps you and your staff facilitate safe dental X-ray practice. These procedures and tools will help you reduce your patients' X-ray burden and give you a marketing tool for your practice.

What Tools Are Available to Help Us?

Here are the educational links to find the most current information on reducing X-radiation dose to your patients from dental radiographic procedures:

Selection Criteria:

http://www.fda.gov/RadiationEmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm116504.htm

NCRP Guidelines:

http://www.ncrponline.org/Publications/Press_Releases/145press.html

http://learndigital.net/articles/article-table-of-contents.htm (look at 2004)

Besides educating yourselves by reading from these sources, there are two simple tools that you can employ to reduce the total X-ray dose the patient receives and to give the patient peace of mind by producing an electronic record of every exposure.

An X-ray Collimator
(fixed to your tube-head)

Recently, Interactive Diagnostic Imaging (IDI, LLC, Marietta, Georgia) introduced a more contemporary and simpler rectangular X-ray collimation device, called Tru-Align. In the past, rectangular PIDs and other devices to secondary collimator the X-ray beam down to a small rectangle have been ignored. Operators felt they could not hit the target with this collimated beam. So round cone PIDs remained the standard of care, the state-of-the-art. IDI changed all that. They produced a rectangular collimation device that can fit on more than 90 percent of existing X-ray machines, collimating the size of the beam to the required NCRP/ADA guideline of restricting the beam to only two percent larger than the image receptor. However, unlike all other devices, the Tru-Align laser aligning collimator system also fixes any image receptor to the tube-head using magnets. This allows for simple alignment without requiring a large beam to hit the target. In full disclosure, I helped develop the design for this device and I am an officer with the company. However, also being one of those educators for the past 30 years that taught you and your dental staff the concepts of rectangular collimation, and being frustrated with the lack of adoption, I believe that this device offers a simple, easy-to-use product that truly helps minimize patients' X-ray dose. The device reduces the skin surface exposure (and deeper structures of course) to the patient by 60 percent because of the reduction in area between the large round cylinder and the small rectangular cone. In addition, this device eliminates horizontal and vertical angulation errors as well as cone cuts. The Tru- Align system will also greatly reduce patient exposure due to re-takes since the receptor is fixed to the tubehead. About the only error one can make is by not putting the receptor and bite block on the corrective. The device is pictured in figure 1.

Although other beam-restricting devices exist, they do not fix the image receptor to the tube-head like the Tru-Align system. The list of these collimators includes:
  1. Rectangular Position-Indicating Collimator - Margraf Dental Manufacturing Inc. (Jenkintown, Pennsylvania) (Fig. 3)
  2. Rinn Universal Collimator - Dentsply Rinn (Elgin, Illinois)
    (Fig. 2)
  3. Tru-Align Laser Collimating System - Interactive Diagnostic Imaging (Marietta, Georgia)

Personalized Dosimetry

Using ion storage technology, there are now simple USB devices, for example the Instadose dosimeter (Fig. 4), that can precisely measure the X-ray dose to the patient for each and every dental X-ray procedure performed over a lifetime. The user, in this case the patient, registers the device at a website that will track the dose received from each radiographic procedure and electronic record and allow the patient to produce a report for themselves or others on what procedures they've had done and the total X-ray dose they have received for all of these procedures. One of these devices is pictured below in figure 4. This technology is offered by several distributors, including:
  1. HealthFirst (Mountlake Terrace, Washington) www.healthfirst.com/index.html
  2. Steinbach and Associates IC Care radiation monitoring badges www.steinbachassociates.com/About_Us.html
  3. Spina Dental (Pittsburgh, Pennsylvania) www.spinadental.com/home.php

References
  1. Radiation Protection in Dentistry: Recommendations of the National Council on Radiation Protection and Measurements, report #145; December, 2003.
  2. Joseph LP. The Selection of Patients for X-ray Examinations: Dental Radiographic Examinations. Rockville, MD: The Dental Radiographic Patient Selection Criteria Panel, US Dept of Health and Human Services, Center for Devices and Radiological Health; 1987.HHS Publication No. FDA 88-8273.
  3. Council on Scientific Affairs. An update on radiographic practices: information and recommendations. Journal of the American Dental Association, 2001; 132:234-8.
  4. Miles DA and Langlais RP: NCRP Report No. 145 New Dental X-ray Guidelines: Their Potential Impact on Your Dental practice. Dentistry Today. 23(9):128, 2004.
Author's Bio
Dale A. Miles is an adjunct professor of oral and maxillofacial radiology at the Arizona School of Dentistry & Oral Health and the University of Texas dental school at San Antonio. He is the CEO of Cone Beam Radiographic Services and VP of Research for IDI, LLC. He is in full-time practice of oral and maxillofacial radiology in Fountain Hills, Arizona.
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