Chapter 19- Radiology

Quality Control and Environmental Safety in Dental Radiography

Learning Objectives

  • Define the key terms.

    • Understanding essential terminology is crucial for grasping quality control in dental radiography.

  • State the objectives of dental radiographic quality control.

    • Objectives should be clear to ensure the production of quality radiographs.

  • Explain the role a competent radiographer plays in quality assurance.

    • The importance of a trained radiographer in maintaining quality standards.

  • Describe quality control tests for monitoring a dental x-ray machine.

    • Essential tests that ensure the x-ray machine is functioning correctly.

  • Describe quality control tests for monitoring a darkroom and processing equipment.

    • Procedures to ensure safe and effective processing of radiographic images.

  • Describe quality control tests for monitoring radiographic image receptors.

    • Methods to evaluate the quality of image receptors.

  • Describe quality control tests for monitoring viewboxes and computer monitors used to view radiographic images.

    • Ensuring viewing equipment is maintained to provide accurate representations of images.

  • List precautions to put in place that protect digital radiographic processing chemistry.

    • Safeguards necessary to maintain the integrity of digital processing chemicals.

  • List data supplied by Safety Data Sheets (SDS) for radiographic processing chemistry.

    • What information is contained in SDS.

  • Describe safe handling procedures for radiographic processing chemicals and materials.

    • Best practices to follow to ensure safety during the use of chemicals.

  • Describe environmentally sound options for disposal of radiographic processing chemistry and materials.

    • Sustainable practices for the disposal of hazardous materials related to radiography.

Quality Assurance

  • Definition:

    • The planning, implementation, and evaluation of procedures utilized to produce high-quality radiographs that maximize diagnostic information (yield) while minimizing patient radiation exposure.

  • Quality Assurance Programs should include:

    • Assessment of current practices: Evaluating existing procedures to identify potential issues.

    • Identification of where & how problems may be occurring: Analyzing workflows to find sources of error or inefficiency.

    • Development of a written plan: Crafting a detailed document that outlines responsibilities and training needs.

    • Record keeping: Maintaining comprehensive records of quality control activities.

    • Periodic evaluation of the plan: Regularly reviewing the quality assurance plan for effectiveness.

Who is Responsible for Quality Assurance?

  • Ultimate Responsibility:

    • The dentist holds the ultimate responsibility for quality administration in a practice.

  • Authority Delegation:

    • Each team member may be delegated authority to manage specific aspects of the quality control program.

Radiographer Competency – It Starts With You!

  • Importance:

    • Essential to ensure that a quality assurance program can effectively produce diagnostic radiographs.

  • Consequences of Operator Errors:

    • Operator errors lead to undiagnostic radiographs, requiring retakes which increase radiation exposure for patients and waste time.

  • Key Competencies include:

    • Not only taking radiographs but also identifying when and why errors occur.

  • Recording of Errors:

    • Operator errors and retakes should be documented for identifying recurring issues, recommended to use a MTC Log Book.

  • Continuing Education:

    • Opportunities for on-the-job training aimed at:

      • Brushing up on existing skills.

      • Improving in areas where deficiencies are noted.

      • Staying informed of new technologies in the field.

Quality Control

  • Definition:

    • A series of tests designed to ensure that the radiographic system functions properly and produces radiographs of an acceptable quality, leading to a high diagnostic yield with low radiation exposure.

Quality Assurance Components

  • Includes both Quality Control & Quality Administration:

    • Quality Control:

      • Involves x-ray machines, darkroom processes, processing equipment, processing chemistry, x-ray film & storage, x-ray viewing, and operator competence.

    • Quality Administration:

      • Assessing needs, developing a written plan, assigning authority and responsibility, providing training, monitoring maintenance, documenting actions, and performing periodic evaluations.

Objectives of Quality Control Tests

  • Maintain high standards of image quality:

    • Ensuring that all images meet pre-defined quality metrics.

  • Identify problems before image quality is compromised:

    • Early detection leads to timely remediation of issues.

  • Keep patient and occupational exposures to a minimum:

    • Reduction of unnecessary radiation exposures.

  • Reduce the occurrence of re-take radiographs:

    • Minimizing patient inconvenience and enhancing workflow efficiency.

Quality Control Tests for Dental X-ray Machines

  • Radiation Output:

    • This is measured using a step wedge during tests. (Refer to Procedure 19-1 on page 267 for more information.)

  • Other tests include:

    • Timer accuracy

    • Milliamperage accuracy

    • Kilovoltage accuracy

    • Focal spot size

    • Filtration (evaluating beam quality)

    • Collimation

    • Beam alignment

    • Tube head stability

      • Noting that drifting tube heads can cause movement during exposures.

Quality Control for the Darkroom

  • Key Areas of Assessment:

    • Safelighting

    • Checking for white light leaks

    • Processing chemistry maintenance

    • Detection of conditions that may lead to film fog

  • Conditions to Maintain:

    • Adequate ventilation

    • Absence of chemical fumes

    • Maintenance of prescribed temperature & humidity ranges

    • Ensure the darkroom is beyond the reach of stray radiation

    • Ensure the room is light-tight

Darkroom Safelighting: Coin Test

  • Procedure (Refer to Procedure 19-2 on page 268):

    • Use a coin and slightly exposed (sensitized) film to determine if safelighting is adequate.

    • Unwrap film in darkroom under safelighting; place it on a counter.

    • Place the coin on top of the film for two to three minutes.

    • Process the film and check for an image of the coin: if an image appears, the safelight has failed.

  • Possible causes for failure:

    • Too short a distance from safelight to counter.

    • Scratches on the safelight filter.

    • Excessive wattage bulb in safelight.

Test for Light Leaks in Darkroom

  • Procedure:

    • Turn off all lights in the darkroom and wait five minutes.

    • Search for visible light leaks and mark areas with tape or chalk.

  • Possible Sources of Light Leaks:

    • Entry door

    • Illuminated dials on equipment located in darkroom

    • Around pipes entering the darkroom

    • Drop ceiling tiles & ventilation screens

    • Fluorescent objects brought into the darkroom

Use of Reference Film to Test Processing Chemistry

  • Process (Refer to Procedure 19-3 on page 269):

    • Use a step-wedge to make checker films, exposing all under the same settings simultaneously.

    • Process one film immediately after preparing fresh chemistry; this film is the reference and should have ideal density and contrast.

    • Store remaining films and daily process a new checker film for comparisons.

    • If the step-wedge checker is two or more steps off from the reference, contact the lab manager.

Image Receptor Quality Control

  • Fresh Film Test:

    • Upon opening a new box of film, process one immediately without exposure.

    • It should appear clear with a slight blue tint; if fogged, do not use the remaining films.

    • Proper storage and protection of films are critical, and they should be used before the expiration date.

  • Photostimulable Phosphor (PSP) Plates & Digital Sensors:

    • Inspect for scratches and bending before intraoral use.

    • USB cord attached to solid-state digital sensors must be checked for crimping or damage.

Quality Control for Equipment to View and Store Images

  • Viewbox:

    • Should emit uniform, subdued light; flickering indicates bulb failure and should be cleaned as needed.

  • Computer Monitor:

    • Regular quality control calibrations as recommended by the manufacturer.

    • Maintain a bright ambient light for clear visibility, ensuring glare is eliminated.

Quality Control for Digital Image Storage

  • Risks:

    • Digital images are vulnerable to threats such as viruses, software malfunctions, and the risk of misplaced or stolen equipment.

  • Data Protection:

    • Ensure digital image data is properly backed up.

    • Keep computer systems and virus protection software current.

    • Password protection is essential; do not store passwords or usernames visibly near the device.

    • Avoid taking wireless devices outside the oral healthcare setting.

Safe Handling of Radiographic Chemicals and Materials

  • OSHA Recommendations:

    • OSHA provides guidelines and regulations regarding safe handling of chemicals and materials.

    • Safety Data Sheets (SDS) must be obtained from manufacturers for every chemical product used in practice.

Safe Handling of Radiographic Chemicals and Materials - FIXER & DEVELOPER

  • Requirements:

    • Establish a well-ventilated darkroom and use personal protective equipment (PPE).

    • Be aware of gas releases such as irritating sulphur dioxide when chemicals are heated or mixed.

    • The developer has a high pH and can cause burns to biological tissues.

    • An eye wash station must be available in the vicinity.

  • Lead Foils:

    • Routine handling of intact lead foil from intraoral film is generally safe.

    • Collect lead foils and send to waste management companies for appropriate disposal.

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