Radiation Safety Policy

Subject: Radiation Safety Policy
Effective Date: January 1994
Revision Dates: August 2002, January, 2008, October 2009

Purpose

To establish protocols designed to minimize radiation exposure to patients and operators; to promote sound radiological health practices, and to promote proper infection control during radiographic procedures.

General Policy

The responsibility for clinical radiation safety and infection control lies with every individual involved with diagnostic radiology including faculty, students, clinical staff and other individuals who are responsible for the proper use and maintenance of radiation equipment and supplies (including film, darkrooms and processors).  The ultimate goal of this policy is to operate under the ALARA concept (As Low As is Reasonably Achievable) with regard to radiation exposure.

The principles of infection control as applied to clinical radiology and described in this policy and in the infection control manual of the School entitled, Hazard Control in the Dental Environment, shall be utilized in all dental school clinics where such services are rendered.

Implementation

I. General Radiation Safety Issues

A. Compliance Statement

The policies and criteria outlined herein adhere to both Federal and Washington State regulations of Radiation Protection and adopt the principles of the FDA Guidelines for Dental Radiographic Examinations.  They have been developed in cooperation with the Radiation Safety Section of the Environmental Health and Safety Department of the University of Washington.  It shall be the obligation of all members of the School of Dentistry who are involved in diagnostic radiology to:

  • adhere to accepted protocols for the safe operation of radiologic equipment and supplies for their own protection and for the protection their patients.
  • follow sound and logical radiological health practices and to report any suspected health hazards to the proper administrative authority.
  • adhere to the infection control policy of the school during radiographic procedures.

B. Responsibility for Monitoring

The Radiation Safety Section of the Environmental Health Department is responsible for implementation of radiation safety measures and controls thereof.  Annual inspections are performed including but not limited to:

  •  Measurements of radiation in controlled and non-controlled areas.
  •  Performance of x-ray units in respect to State and Federal regulatory codes.
  •  Identification of non-compliance with University policy or regulatory codes.
  •  Evaluation of radiological safety programs by observing their effectiveness in providing protection and the level of compliance.

The Director of Oral Radiology, School of Dentistry, shall act as a liaison between individual users of radiation and the Radiation Safety Officer of the University of Washington and assist the Radiation Safety Officer in the implementation of the Radiation Safety Policy.

C. Authorized Users

The use of diagnostic x-ray equipment in the practice of dentistry at the UW School of Dentistry shall be restricted to those individuals described in this section.

Predoctoral Students:  The operation of x-ray equipment by predoctoral students is authorized but limited to the following restrictions:

  • The operator shall have didactic and preclinical training and a passing grade in oral radiology.
  • The x-ray exposures shall be authorized by a clinical instructor of the School of Dentistry as evidenced by the instructor’s signature on the prescription.
  • A clinical instructor shall approve the quality of the radiograph as evidenced by the instructor’s signature on the record.

Graduate Students:  The operation of x-ray equipment by unlicensed graduate students is authorized but limited to the following restrictions:

  • The operator shall possess a dental degree.
  • The x-ray exposure shall be authorized by a member of the faculty of the School of Dentistry as evidenced by the faculty member’s signature on the Request for Radiographic Exam form as outlined in the Clinic Procedures Manual, section 5-F, Managing Radiographs.
  • A member of the faculty shall be available for consultation when required.
  • A faculty member shall approve the quality of the radiograph as evidenced by the faculty member’s signature on the record.

Radiology Technicians:  The operation of x-ray equipment by School of Dentistry radiology technicians and staff is authorized but limited to:

  •  The x-ray operator shall have adequate training in radiographic techniques.
  •  The x-ray exposure shall be authorized by a member of the faculty of the School of Dentistry as evidenced by the faculty member’s signature on the prescription.
  •  A member of the faculty should be available for consultation when required.
  •  A faculty member shall approve the quality of the radiograph as evidenced by the faculty member’s signature on the record.

Faculty members:  All members of the faculty of the School of Dentistry possessing a dental degree are authorized to prescribe radiographic examinations.

D. Radiation Protection Standards

Occupational doses for individuals are:

  • an annual limit is to be the more limiting of: total effective dose equivalent being equal to 5 rem (0.05 Sv)i or the dose equivalent to any organ, tissue, or extremity (other than the lens of the eye) being equal to 50 rem (0.5 Sv).  The annual dose equivalent limit to the eye will become 15 rem (0.15 Sv).
  • WAC 246‑221 requires assessment and control of fetal doses.  A pregnant worker should voluntarily declare her pregnancy in writing to her employer and include her estimated date of conception.  The embryo/fetus should not receive a dose equivalent greater than 0.5 rem (50 mSv) during the entire pregnancy.  Special dosimeters can be provided to declared pregnant workers to evaluate fetal doses.
  • occupationally exposed minors (under 18 years of age) should not receive an dose equivalent in excess of 0.5 rem (50 mSv)

Monitoring will be required for any individual who could potentially receive a dose in excess of 10% of any applicable limits.

Any individual monitoring device used for monitoring the dose to the whole body shall be worn at the unshielded location of the whole body likely to receive the highest exposure.  When a protective apron is worn, the location of the individual monitoring device is typically at the neck (collar).

Any additional individual monitoring device used for monitoring the dose to an embryo/fetus of a declared pregnant woman shall be located at the waist under any protective apron being worn by the woman.

II. Guidelines for Prescribing Dental Radiographs

A. General Principles

The goal of every radiographic examination will be to seek information which will influence the diagnosis and treatment of the patient, thereby providing a benefit which otherwise could not be realized.

The exposure of each patient will be as individualized as feasible.  There shall be no “routine” radiographic examination.  Radiographic examinations shall be carried out solely based on clinical indications.  Radiographs shall not be taken solely for legal, documentary, teaching, or administrative purposes.

To minimize unnecessary radiation to the patient, previous radiographs of the patient should be obtained.  These will serve as important guides for the ordering of new radiographs and to provide a better understanding of disease progress.

B. Prescription Guidelines

The Guidelines for prescribing dental radiographs are based on the recommendations issued by U.S.  Department of Health and Human Services, Public Health Service, F.D.A., and shown in Appendix A and the standard for requesting a referral to Radiology is in the Clinical Procedures Manual, section 5F, Managing Radiographs.

III.  Radiation Protection Measures for Patients and Personnel

A. Patient Protection from Ionizing Radiation

  • The authorized user shall employ those operating parameters (kVp, mA, exposure time, film screen combinations, and collimation), which result in the lowest possible radiation dose to the patient and still produce desired diagnostic information.
  • A lead impregnated apron is recommended to shield the trunk of the body and the gonads of the patient.  The lead equivalent of the apron should be at least 0.25 mm.
  • A thyro-cervical shield is recommended to protect the patient’s neck when the use of it does not interfere with the retrieval of diagnostic information. This shield shall be provided for children. When it will not interfere with the examination.
  • Before any exposure is initiated the operator shall ensure that the tube head has its proper and stable position.
  • Film holders with indicators for proper x-ray beam alignment are recommended for intraoral periapical and bitewing radiography.  Rectangular collimators are recommended in combination with these film holders.
  • Retakes should be approved by a faculty supervisor and should be taken only for a valid clinical reason, not for the purpose of improving the esthetics of the radiograph.

B. Personnel Protection from Ionizing Radiation

  • In no instance shall the x-ray operator or an assistant hand-hold a film during exposure.
  • During each exposure the operator shall stand behind a protective barrier.  Only the patient should be in the path of the useful beam.
  • Neither the tube housing nor the cone shall be hand held during exposure.
  • When a patient needs assistance or reassurance during exposure, then a third party, such as a member of the patient’s family, may be allowed to stay in the x-ray room to assist with the procedure, provided that the individual is issued appropriate protective devices and instructed to stay out of the path of the primary beam.  The third party shall not be pregnant or under the age of eighteen.

C. Recording of Radiographic Procedures

An entry which includes the date and type of exposure shall be made in the Radiology Log of the patient’s dental record for each radiographic procedure performed.  Patient records shall be reviewed by the faculty with respect to record entries in the Radiology Log and in the progress notes.  All films or film mounts shall be labeled with the patient’s name and date of exposure and stored in the patient’s record.  All intraoral films are to be mounted and labeled.  Large extra-oral films are to be labeled directly on the film using identification labels.

D. Facilities Management

The management of radiology equipment and facilities shall be in compliance with state law and university environmental health and safety policy as described in Appendix B.  The Intraoral Dental X-ray Unit Test and Instructions (Form RSO 404) shall be used in the evaluation of facilities as displayed in Appendix C.

Darkroom equipment and procedures:  In addition to the regular maintenance of darkroom equipment and change of processing chemicals regular evaluations of the performance of the processing systems shall be undertaken.  The Division of Oral Radiology will regularly provide standard dental radiographs which have been exposed under standardized conditions. These developed radiographs will be analyzed and recorded.  Other currently accepted techniques for this evaluation can also be employed.  Records for each processor system should be kept in which dates and results of tests should be noted.  In each Department or facility where processing of radiographs takes place an individual shall be designated the responsibility for the processing unit.  This individual shall be responsible for the daily supervision of procedures and equipment and shall report faulty function etc. to the maintenance office.  In turn, the maintenance office shall keep logs of services and report disturbances to the Office of clinical affairs and the Safety officer.  A standard test film shall be used to determine the performance of each processing unit used in the school.  Deviation from normal shall be reported to the Office of Clinical Affairs.

Viewing facilities:  It is the responsibility of each department to keep viewing equipment and facilities in an adequate operating condition.

ERadiographic Image Quality Control

 In an effort to maintain radiographic image quality at a high level, each radiographic examination shall include a critical review of image quality with respect to projection, exposure, and possible processing errors or artifacts.  Remedial measures such as reinforcement of instructions, individual tutorials, etc., should be employed.

Audits: At least once a year randomly selected records of dental school patients and radiology process should be reviewed by Office of clinical affairs with regard to prescription and recording of radiographic procedures as well as image quality.

IV. Radiographic Duplication

Access to a duplicate of radiographs is a legal right of each patient of record.  Patients, or their designated representatives may obtain such duplicates using the protocol in the Patient Records policy.

 Appendices:
Appendix A, Guidelines for Prescribing Dental Radiographs

Appendix B, Radiographic Equipment and Facility Management

Dean of UW SOD:

Martha Somerman, Dean of the UW School of Dentistry

October 8, 2009

Appendix A

Guidelines for prescribing dental radiographs

Modified after recommendations issued by U.S. Department of Health and Human Services, Public Health Service, Food & Drug Administration.  The recommendations in this chart are subject to clinical judgment and may not apply to every patient.  They are to be used by dentists only after reviewing the patient’s health history and completing a clinical examination.  The recommendations do not need to be altered because of pregnancy.

Adults

NEW PATIENT Radiographs of recent date (1-2 years old) of sufficient quality and quantity. low risk bitewing
high risk PAN + bitewing
Previous radiographs more than 2 years old or more recent, of insufficient quality and quantity low risk PAN + bitewing
high risk FMS + bitewing (PAN)
No previous radiographs low risk PAN + bitewing
high risk FMS + bitewing (PAN)
RECALL PATIENT Use available previous radiographs low risk bitewing 24-36 month interval
high risk bitewing 12-18 month interval

Children and Adolescents

NEW PATIENT Primary Dentition bitewing if contacts closed
Transitional Dentition PAN + bitewing
RECALL PATIENT bitewing 12-24 month interval Panoramic radiograph to assess 3rd molars and growth and development when needed.

Clinical situations for which radiographs may be indicated include:
Positive Historical Findings

  1. Previous periodontal or endodontic therapy
  2. History of pain or trauma
  3. Familial history of dental anomalies.
  4. Post-operative evaluation of healing
  5. Presence of implants

Positive Clinical Signs/Symptoms

  1. Clinical evidence of periodontal disease
  2. Large or deep restorations.
  3. Deep carious lesions
  4. Malposed or clinically impacted teeth.
  5. Swelling.
  6. Evidence of facial trauma.
  7. Mobility of teeth.
  8. Fistula or sinus tract infection.
  9. Clinically suspected sinus pathology.
  10. Growth anomalies.
  11. Unexplained bleeding.
  12. Positive neurologic findings in the head and neck.
  13. Evidence of foreign objects.
  14. Unexplained sensitivity of teeth.
  15. Facial asymmetry.
  16. Abutment teeth for fixed or removable partial prosthesis.
  17. Oral involvement in known or suspected systemic disease.
  18. Pain and/or dysfunction of the temporomandibular joint.
  19. Unusual eruption, spacing or migration of teeth.
  20. Unusual tooth morphology, calcification or color.
  21. Missing teeth with unknown reason.

Patients at high risk for caries may demonstrate any of the following

  1. High level of caries experience
  2. History of recurrent caries
  3. Existing restoration of poor quality.
  4. Poor oral hygiene.
  5. Inadequate fluoride exposure.
  6. Prolonged nursing (bottle or breast).
  7. Diet with high sucrose frequency.
  8. Poor family dental health.
  9. Developmental enamel defects.
  10. Developmental disability.
  11. Xerostomia.
  12. Genetic abnormality of teeth.
  13. Many multi-surface restorations.
  14. Chemo/radiation therapy.

 

Appendix B

Radiographic Equipment and Facility Management

Dental x‑ray rooms

Dental x‑ray rooms are to be in compliance with Washington Administrative Code (WAC) 246‑225‑030 (General Requirements/Plan Review).  These regulations address items necessary for a proper evaluation of safety and shielding requirements.

New or remodeled dental facilities are exempt from WAC 246-255‑030 conditions requiring submission of shielding calculations and floor plans to the State of Washington Department of Health for plan review.

A qualified expert (as determined by State of Washington Department of Health) must evaluate safety and shielding requirements of all new or remodeled installations using National Council on Radiation Protection and Measurements Report No. 49.

Dental x‑ray equipment

Dental x‑ray equipment is to be in compliance with Washington Administrative Code (WAC) 246‑225‑110 (Intraoral Dental Radiographic Systems).

Items addressed in the WAC include: (1) source to skin Distance (SSD), which should be 18 centimeters or more for equipment operated at the University of Washington; (2) field limitation, which should be contained within a circle having a diameter no greater than 7 centimeters (3) adequate timers and exposure controls; (4) exposure reproducibility; and (5) operating controls.

Radiographic Quality Assurance

RQA entails a system of policies and procedures with the aim to ensure that the radiographic diagnostic facilities produce consistent high quality images and minimizing the risks to patients and providers.

Periodic surveys and inspections

  • x‑ray apparatus and related items
    All intraoral x‑ray machines are generally inspected twice per year.  One inspection for general safety characteristics and adherence to WAC 246‑225‑110 is done yearly by the UW Radiation Safety Office of Environmental Health and Safety.  A similar inspection is also done yearly by the Scientific Instruments Division at the University of Washington.  Occasional inspection by the State of Washington Department of Health also occur.
  • dose measurements
    Estimates of patient dose measurements are taken at the time of inspections by the Radiation Safety Office and Scientific Instruments staff.  In addition, area measurements are made by Radiation Safety Office staff to evaluate exposure potential to operators and nearby personnel.