Frequently Asked Questions - Dental Radiographs

In a dental office, only a dentist has the authority to prescribe dental radiographs.

A dentist must review the patient’s health history and complete a clinical examination before prescribing radiographs.

When considering the use of ionizing radiation, the use of radiographs must be approached in a responsible way that maximizes diagnostic value, given the clinical context, without exposing patients to unnecessary amounts of ionizing radiation. Dentists must exercise professional judgement to achieve the appropriate balance between these two considerations. A dentist’s decision about the number, type and frequency of radiographs should be based on an individual patient’s dental history, clinical signs and symptoms.

• Where possible, dentists should obtain copies of recent radiographs from other practitioners who have cared for the patient, and perform a clinical exam.
• Once the dentist has done the above they may exercise professional judgement to prescribe appropriate individual radiographs to help formulate an initial diagnosis for the patient.

Again, the principle of ALARA applies and dentists must perform a clinical examination before prescribing additional radiographs. Dentists should base their decision about the number, type and frequency of radiographs at recall appointments on existing disease and the expected occurrence of disease. For example, dentists should determine the frequency of bitewing radiographs on the basis of caries risk assessment. A decision about radiographs should never be based on inflexible time periods alone, (such as bitewing radiographs every six months).

No. The taking of radiographs requires a patient-specific prescription. However, a dentist can prescribe radiographs for a subsequent appointment to follow up on a previously detected condition/pathology or to confirm a diagnosis or evaluate treatment provided. The dentist should document the prescription for future radiographs in the patient’s chart.

The College has published a PEAK article on Considerations for the Use of Ionizing Radiation in Dentistry.

The Canadian Dental Association, Health Canada, and the American Dental Association have also published general recommendations and guidelines. These can be found at:

• https://www.cda-adc.ca/_files/position_statements/xradiation.pdf
• http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/99ehd-dhm177/index-eng.php#a9
• https://www.ada.org/-/media/project/ada-organization/ada/ada-org/files/resources/research/oral-health-topics/dental_radiographic_examinations_2012.pdf?rev=b074dde4cb0b4cc5a2343feb3f89b66d&hash=AF0BCF8A12C4937B2921177FE650CC54

Patients have the right to consent to, or decline, radiographs. Whenever a patient, patient’s guardian or substitute decision-maker refuses recommended radiographs, the dentist should explain the rationale for their recommendation and the consequences of not taking them. If radiographs are still refused,  the dentist should document the informed refusal in the patient’s chart. If the dentist believes the refusal compromises their ability to make an accurate diagnosis and/or provide appropriate treatment they can refuse to provide compromised care as dictated by the patient.

Only persons meeting the qualifications specified in the Healing Arts Radiation Protection (HARP) Act and its regulations can take radiographs. It is the responsibility of the dentist who has taken on the role of the Radiation Protection Officer (RPO) to ensure that all X-ray operators, including dental assistants, meet the qualification requirements under the HARP Act. Staff qualification documents must be readily available in the event of an inspection.

The following persons are permitted to take radiographs in a dental office:

1. Dentists who are registered members of the College may take radiographs. Dentists who hold a valid CT Member Authorization from the College may take CT scans at any dental facility with a valid dental CT scanner facility permit, as long as they have received onsite training in the safe operation of the dental CT scanner installed in that facility. (Reference: CT Member Authorization (rcdso.org) and  Standard of Practice for Dental CT Scanners). 
2. Dental hygienists who are registered members of the College of Dental Hygienists of Ontario (CDHO) may take radiographs with dental radiographic equipment, excluding dental CT scanners.
3. Medical radiation technologists (MRT) registered with the College of Medical Radiation and Imaging Technologists of Ontario (CMRITO) may take radiographs with dental radiographic equipment. They may also operate dental CT scanners under the onsite supervision of a qualified prescribing dentist. (Reference: CT Member Authorization (rcdso.org) and Standard of Practice for Dental CT Scanners)  

Any of the following items are acceptable as proof of qualifications:

• A diploma, certificate or transcript confirming successful completion of a dental assisting course/program.  Courses/programs are approved by the Director of X-ray Safety at the Ministry of Health (“HARP-approved course/program”).  A list of schools which currently offer HARP-approved courses/programs is available from the X-ray Inspection Service (XRIS) at xris@ontario.ca, OR 
• A diploma, certificate or transcript confirming successful completion of a dental assisting course/program that has been approved by the HARP Commission (prior to 2009), OR
• A certificate from the RCDSO confirming successful completion of the x-ray safety update course taken during the December 1983 – December 1986 period; OR
• A HARP letter issued by the Director of X-ray Safety 

Note on HARP letters:

XRIS no longer issues HARP letters. Historically, HARP letters were issued to some graduates as an acknowledgement letter indicating that the individual had completed a HARP-approved course/program. These HARP letters will continue to be accepted as proof by XRIS. XRIS however will not reissue any lost HARP letters. Individuals with lost HARP letters will be required to obtain one of the other applicable documents from the above list.

Individuals with dental training from outside of Ontario

Individuals with dental training from outside of Ontario are not automatically qualified to operate X-ray machines in Ontario. They will need to meet the same requirements outlined above by successfully completing a HARP-approved course/program. Individuals who wish to seek exemptions based on their previous education should inquire with one of the current HARP-approved schools to have their qualifications reviewed. This includes internationally-trained dentists and dental hygienists who are not licensed in Ontario as well as internationally-trained dental assistants.

Please note: an NDAEB Certificate does not represent HARP Certification in Ontario. The HARP Certificate is a separate provincial requirement.

For more information on these requirements including how to obtain a copy of the current HARP-approved schools list, contact XRIS (xris@ontario.ca). 

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 act as the RPO.

The RPO:

• establishes and maintains procedures and  quality tests  for the safe operation of the x-ray equipment and keeping records of these test results;
• ensures that the x-ray equipment is maintained, meets the standards prescribed by the regulations, all x-ray operators are qualified according to the HARP Act;
• ensures that protective accessories (for example, lead aprons and thyroid collars) are available for persons who may receive exposure to x-rays in the facility. The College recommends the use of both thyroid and gonadal shielding whenever possible, particularly for children and adolescents.

The dentist who serves as the RPO in the dental facility must ensure that only qualified persons take dental radiographs.

If a dentist provides a patient-specific prescription for the radiographs, qualified dental staff may take these radiographs without the dentist being present.

The HARP Act does not require the use of radiation dosimeters. However, their use is strongly advised. The use of radiation dosimeters can be reassuring to dental staff. Readings serve as a radiation exposure record and can help dentists minimize their staff’s occupational exposure to radiation.

If a staff member specifically requests one or is pregnant, then dentists should provide them with a dosimeter. A new office is encouraged to monitor their workers for the first 6 months to a year to establish a baseline measurement and to confirm that shielding is adequate and safe work practices are being followed.

According to the Ministry of Labour, dosimeters are required for workers operating a cone-beam CT in a dental office.

Dosimeters are also required for special circumstances or specific practice environments where some staff members may have to remain in the operatory room with a pediatric or uncooperative patient (i.e. to hold the patient in place during an exposure).

All dental x-ray machines must be registered by the owner and new installations must be approved by the Director of X-ray Safety with the X-Ray Inspection Service (XRIS) of the Ministry of Health and Long-Term Care. Plan approval ensures both patient and staff safety from unnecessary radiation exposure.

Dentists require written approval from XRIS before installing a new dental x-ray machine, replacing an existing one or making changes to the installation. Dentists must submit a plan of the dental office layout, accompanied by additional forms and information.

The owner of the dental x-ray machine must submit a new schematic plan in electronic format with every application. The shielding calculations should be indicated on the schematic plan and described on the application forms. The exact amount of shielding required for the x-ray room depends on the usage or workload of the dental x-ray machine.

An XRIS inspector may visit any dental facility to inspect the operations, examine records and conduct tests to determine compliance with the HARP Act. Under the  Act,  inspectors can enter and inspect dental facilities at all reasonable times without an appointment. Inspectors may provide dentists with a one-week window for office inspection visits.

We recommend that dentists have all the necessary paperwork, including any forms or plans, readily available at the office.

The HARP Act requires that every dental office institute a Photographic Quality Assurance (QA) Program (QA). Photographic QA is a program of activities designed to ensure that diagnostic imaging is carried out with the maximum benefit to the patient, at a minimum of risk. The program requires that dentists perform acceptance testing on all new and used x-ray equipment. Dentists must also conduct daily and annual tests as part of their QA program. 

Learn more by reading this Dispatch article on information for dental x-ray facilities. 

It is preferable to provide digital radiographic images in an electronic format. Traditional film-based radiographs can also be scanned, digitized and provided in an electronic format. The dentist providing the information should ensure that the selected format is compatible with the receiving dentist’s electronic records management system so that the files can be opened and viewed.

Dentists must ensure that radiographic images are of diagnostic quality. In this way, the subsequent dentist receives the necessary information and the patient receives the diagnostic value of the digital radiographs. This will help reduce the patient’s exposure to ionizing radiation by minimizing the need for additional images and unnecessary retakes.

Patient personal health information associated with digital radiographic images and file information is protected in compliance with current requirements of the Personal Health Information Protection Act, 2004, and the directives of the Information and Privacy Commissioner of Ontario (IPC/ON).

Dentists should avoid using e-mail to communicate the personal health information of patients unless they are employing a secure e-mail service with strong encryption.

Dentists who are members of the Ontario Dental Association can use the Canadian Dental Association’s e-Referral Service through which personal health information can be shared securely. Both the dentist providing the information and the dentist receiving it must be registered users to be able to use this service.

The Information and  Privacy Commissioner of Ontario (IPC/ON) advises that even if patients are willing to accept the risk of unauthorized disclosure of their personal health information, this does not alleviate health information custodians of their duty to take reasonable steps to safeguard personal health information in their custody and control.

Digital radiographic images can be copied to portable media or storage devices, such as a CD-ROM or USB flash drive, and provided to the patient. With the patient’s consent, these can be forwarded to another dentist by registered mail or courier. If hard copies are provided, the digital radiographic images must be printed on photographic quality paper using a printer that is capable of producing high-resolution photographic quality prints.

Ontario dentists with the required education and training can apply to the College to prescribe, order and take dental CT scans, and to install and operate a dental CT scanner. All dentists who wish to prescribe, order and take dental CT scans must register with the College as a prescribing dentist. This includes all dentists who are specialists in oral and maxillofacial radiology and all dentists who practise in hospital dental departments. In addition, every dental facility where a dental CT scanner is installed and operated must have a facility permit issued by the College.

Dental hygienists and dental assistants are not permitted to take dental CT scans.

In accordance with the College’s Standard and  the HARP Act, only authorized dentists and qualified  and registered medical radiation technologists acting under the on-site supervision of a qualified prescribing dentist can take dental CT scans.