California Dental X-Ray Quality Assurance Requirements

On October 3, 2012, new California State regulations finalized by the California Department of Public Health Radiologic Health Branch (CDPH-RHB) require dental offices who process x-rays with traditional radiographic equipment to meet specific quality assurance standards.  CDPH-RHB is looking to develop similar regulations for digital radiography.

The new regulation requires that dentists conduct an acceptable quality assurance program that includes daily tests on the performance of dental film processing to ensure consistent x-ray quality. The requirement went into effect on October 3, 2012, after which time the state inspectors will be checking for compliance. To view the California State law, go here then search for Title 17, Section 30311.1 (You cannot link directly to sections in California’s online Code of Regulations).  The new regulations require dental offices using traditional film radiography to:

  • Store radiographic films in accordance with manufacturer’s recommendations.
  • Store, use, and maintain intensifying screens, grids, viewers, film processing equipment, and chemicals according to manufacturer’s recommendations.
  • Provide a technique chart for each view commonly performed for each x-ray machine.
  • Select a reference film for use in daily comparisons of dental radiographs.
  • Compare clinical radiographs to the selected reference film for density, contrast, sharpness, and overall quality.
  • Take corrective action when observable changes occur.
  • Maintain records of the corrective actions taken.

Aluminum Step Wedges

An Aluminum Step Wedge enables every dental office to setup a simple and economicalquality assurance program for clinical dental radiography. Aluminum Step Wedges can also be used in the calibration of x-ray machines, and are used as a quality assurance test in monitoring the film processing used in dental radiography. Aluminum Step Wedges are also used for measurement and analysis of x-ray beam quality. As in all tests, it is necessary to establish an acceptable baseline or standard for the x-ray unit’s performance.

Why use a step wedge?

A High Purity Aluminum Step Wedge allows you to evaluate the performance of the X-ray machine and the processing system. Step wedges can also be used in the calibration of x-ray machines, and are used as a quality assurance test in monitoring the film processing used in dental radiography. Step wedges are also used for measurement and analysis of x-ray beam quality. A manufactured aluminum step wedge produces images of consistent quality. While not a requirement when using digital sensors; a step wedge would provide the invaluable benefit of being able to monitor the performance of the x-ray machine and the digital sensors.

Lessons from a Frog…

The old anecdote about boiling a frog usually goes something like this. If you drop a frog into a pot of boiling water, it will immediately jump out. However, if you place a frog into lukewarm water, and heat the water slow enough, it will allow itself to be boiled to death. Not exactly a nice story, but it serves a purpose. It perfectly illustrates the danger of a slippery slope, or for our intent, a decline in quality that is so gradual no one notices.

Why is a step wedge the best and simplest solution?

It does not matter whether one uses film or digital sensors, they begin to deteriorate from the moment they are made. They can degrade too far to provide one with a diagnostic quality x-ray. With both film and sensors, the deterioration rate is so slow that even a leading dentist did not realize that his x-ray quality had declined. Once the x-ray quality has declined, one could easily either misdiagnose a patient, or miss a diagnosis altogether. The potential harm to a patient and resulting malpractice lawsuits are something that anyone would prefer to avoid. A quality assurance program that uses a step wedge is a very simple way to ensure x-ray quality with a consistent and measurable test. A step wedge provides the additional benefit of checking all parts of the imaging chain. Our step wedge fits on a #2 film or Digital Sensor and is easy to use. It only takes a few minutes to start your Quality Assurance Program. Do you want to go the way of the frog or would you rather gain the peace of mind that your x-rays are of the most consistent quality?

What are test X-rays?

Test X-rays are X-ray images that should be taken on a regular basis using a high purity aluminum step wedge and bitewing exposure factors. A full range of grey should be visible – one end of the X-ray should be light grey and the opposite end should be almost black. 9 lines of grey should be clearly visible.

X-ray Quality Assurance Program

When starting a quality assurance program with a step wedge; it is necessary to first take a reference x-ray image. Place the step wedge over a film or sensor and position the x-ray field over the step wedge. Record the date, operatory, X-ray machine, kVp, mA, exposure time, Source-to-Image Distance, and developing time.

This information will be necessary to conduct this test in the future. Take an exposure (and if using film, develop the film as usual). Save this image as the reference image for that x-ray machine.

Once a month or any time that you suspect that there may be a problem with your x-ray system, create another image in the same manner as described above. Compare this image to the reference image. If you notice a change in density of “2 steps”, you are alerted that there is a problem and corrective actions should be taken before your radiographs deteriorate in diagnostic quality.

Margraf Dental’s Stepwedge 

Our high purity aluminum step wedge is manufactured from aircraft grade, 6061 97.9% pure aluminum. When measured with digital-subtraction radiology, the 6061 97.9% pure aluminum had the most consistent density throughout the raw material.

Our aluminum step wedge measures 1 1/2″ x 3/4″ (38mm x 19mm) and will conveniently fit on a #2 periapical film or sensor. Our #90-951 is 9mm thick with 9 – 1.0mm increments or steps. Also available for special order are other variations of thickness or number of increments (steps). We also manufacture larger step wedges that can be used to measure or test the quality of a Pan-Ceph unit.