Friday, May 06, 2011

Is the NOMAD Pro Handheld Dental X-Ray System Safe?

Apparently so.

You know, around the California Dental Association meeting I receive all sorts of promotional e-mails from dental equipment and supply vendors. Today's was from NOMAD.

The NOMAD® Pro Handheld X-ray System has revolutionized the way dental x-rays are taken. One lightweight 2.5-kg NOMAD does the work of multiple wall-mounted systems, and can be used with digital sensors, phosphor plates, or traditional film.The operator can stay chairside with the patient, making it ideal for wiggly children and anxious or special needs patients. The innovative internal shielding of the NOMAD protects the operator from radiation leakage, while the backscatter shield protects from radiation reflected from the patient. Its lightweight battery-powered design permits dentists to use the device outside the office, allowing them to treat patients that previously would not have had access to such care.

But, I always wondered if the system was safe.

The operator is standing so close to the patient and the concentrated X-ray beam, you would think the scatter radiation would be dangerous. After all, in conventional dental X-ray systems, the operator, as a matter of course, leaves the room prior to the exposure.

So, a little research and I found a study (Pdf).

Objectives: A new hand-held battery-operated portable X-ray system was tested for possible leakage radiation through the existing heavy metal compounds surrounding the Xray tube, backscatter radiation through the lead-filled acrylic shield attached at the end of the exit tube and patient exposure.

Methods: Dose measurements were conducted using a DXTRR phantom and a water phantom. All measurements were recorded using calibrated thermoluminescent dosimetry (TLD), calibrated Unfors Model 583L dosemeter, and a calibrated Radcal MDH model 1015 dosemeter. The settings for all exposure were 60 kVp, 2.3 mA and 0.25 s using Kodak Insight (Class F) film.

Results: All backscatter measurements, in front of the shield, behind the shield, at the finger of the operator, the operator’s chest, eyes and gonads were significantly below the maximum permissible radiation leakage as per the United States Food and Drug Administration regulations (100 mR h21). Our measurements indicate that the exposure would be well within the occupational maximum permissible dose for an occupationally exposed person. Film dose was consistent with the manufacturer’s recommendations. As a result of our measurements, the State of New York Bureau of Environmental Radiation Protection granted us a variance to use the NOMADTM on a case-by-case basis.

Conclusions: Our data have shown that the NOMADTM presents risks that are no greater than with standard dental radiographic units to the patient or operator and the measured doses are well below recommended levels.

Dentomaxillofacial Radiology (2008) 37, 109–112. doi: 10.1259/dmfr/33303181

Here is how they tested:

And, the conclusions of the study:
The NOMADTM is easy to set up and use. It meets radiation safety standards and does not requirepersonal dosimetry. It has potential for use in forensic dentistry, humanitarian missions, nursing homes and with developmentally disabled patients. Our test data have shown that the NOMADTM presents no risk to the patient or to the operator and the measured doses are well below recommended levels. The image quality of the radiographs is equivalent to that produced with standard X-ray equipment (data not shown in this report). We calculated that the operator dose is well below the 500 mrem year21 threshold that mandates use of personal dosemeters in New York. All backscatter measurements were significantly below the maximum permissible radiation leakage as per the United States Food and Drug Administration regulations (100 mR h21). These data indicate that use of the NOMADTM hand-held device results in a very low radiation exposure to patient and operator.
So, would I consider purchasing a NOMAD?

Probably yes. I would think that the ease of use and the portability would be a decided factor while planning a new dental office or as a replacement/addition of dental X-ray units. Plus, no more worry of either hiding the equipment in a side mounted cabinet or wall placement for esthetics.

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