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X-ray Safety

Information for dental x-ray facilities

Originally published in the August/September 2014 issue of Dispatch. Updated November 2018. 

This article has been prepared with information provided by the X-ray Inspection Service (XRIS) of the Ministry of Health and Long-term Care and highlights some of the key legislative requirements.

Background

X-ray machines in Ontario that are used for the irradiation of a human being for therapeutic or diagnostic purposes are regulated under the Healing Arts Radiation Protection (HARP) Act and Regulation 543, x-Ray Safety Code. This legislation applies to dental facilities and to x-ray machines used by medical, chiropractic and podiatric facilities, as well as hospitals.

Plan Approval Process

Written approval from the xRIS is required before installing a new dental x-ray machine, replacing an existing one or making changes to the installation. 

The HARP Act requires that owners of x-ray machines designate a person as a radiation protection officer (RPO). In a dental facility, only a dentist can be the RPO.

The prime responsibilities of the RPO include:

  • establishing and maintaining procedures and quality tests for the safe operation of the x-ray equipment and keeping records of these test results;
  • ensuring that the x-ray equipment is maintained and meets the standards prescribed by the regulations;
  • ensuring that all x-ray operators are qualified according to the HARP Act;
  • ensuring that protective accessories (for example, lead aprons and thyroid collars) are available for use by persons who may receive exposure to x-rays in the facility.

XRIS Inspection Visits

An x-ray Inspection Service (xRIS) inspector at the Ministry may visit any dental facility to inspect the operations, examine records and conduct tests pertaining to the installation and use of x-ray equipment to determine compliance with the HARP Act.

During the visit, the inspector may review a number of documents, which must be available onsite. It is important that dental staff members are aware of the exact location of these documents for easy accessibility.

These documents include:

  • up-to-date approved plan for radiation shielding;
  • quality test results up to six years old;
  • x-ray equipment registration;
  • proof of staff qualifications (valid professional membership: RCDSO, CDHO, CMRTO; documentation of completion of approved course in dental radiography for dental assistants).

In the event of a dental practice purchase or merger, it is advisable that records listed above be acquired as part of the transfer of assets.

Equipment Testing

Acceptance testing is performed on all new and used x-ray equipment in order to:

  • determine a baseline performance to be used as a comparison standard for future maintenance and quality testing;
  • verify equipment performance and ensure safety;
  • ensure the equipment meets legislated standards as specified in the HARP Act and Regulation 543.

As a best practice, it is recommended that acceptance testing be performed immediately after installation of the x-ray equipment and before it is first used on patients. The RPO must ensure acceptance results are submitted to the Director of x-ray Safety within 60 days of installation.

Quality testing is performed on all new and used x-ray equipment in order to:

  • ensure patient safety;
  • confirm that equipment meets the requirements of the HARP Act and Regulation 543;
  • detect any trends/deterioration in equipment performance that could affect the quality of radiographs.

The following quality tests must be conducted every 12 months and upon alteration or servicing of the machine:

  • patient entrance exposure measurements;
  • collimation;
  • half-value layer.

The HARP Act requires that a Photographic Quality Assurance Program (QA) be instituted in every dental office.

For conventional x-ray machines, records may include temperature charts, results of sensitometric analysis, logs of processor maintenance and number of films processed, and documentation of corrective action.

The radiographic quality control measures that are required for digital radiography are:

  • Perform daily photographic control testing on each x-ray machine.  The Ministry of Health X-ray Inspection Services (XRIS) recommends that offices test each x-ray machine by taking an image of an object that would show up on the screen, such as a step wedge or a metal clip, before the x-ray machine is used on a patient.  The image should be stored in a “QA test file” as documentation.
  • Record in a logbook, the number of images exposed per x-ray machine per day.
  • Record the number of retakes for each machine per day
  • Record the reasons for retaking the images and determine if the problem stems from operator error or from x-ray equipment/sensor malfunction.  Corrective measures such as equipment recalibration or staff retraining in imaging technique can then be taken accordingly and recorded in the logbook.  

Records must be available as evidence that photographic quality control is being done every day of use.  Records must be maintained for 6 years. These requirements also apply to panoramic x-rays machine.

For clarification, you can contact the X-Ray Inspection Service (XRIS) at the Ministry of Health and Long-Term Care:

Phone: 416-327-7937
Fax: 416-327-8805
General inquiries: xris@ontario.ca