Guide to Radiation Safety in Dental Radiography Released

Dental professionals routinely face critical questions about radiation practices: How to minimize patient dose while maintaining diagnostic image quality? What to do when new digital equipment underperforms? The International Atomic Energy Agency (IAEA) has compiled expert guidance to address these challenges in dental radiology.

Manufacturer Responsibilities in Dental Radiology

X-ray equipment manufacturers must provide comprehensive quality assurance tools and guidelines alongside their devices. This is particularly crucial for cone beam CT (CBCT) systems and panoramic units. User manuals should detail testing protocols and expected outcomes, while device-specific test objects or phantoms should be included as standard components.

Key Factors for Dose Reduction

Radiation optimization remains central to dental imaging. Professional associations and national agencies should provide clear guidance on minimizing patient exposure while maintaining diagnostic efficacy. Below are modality-specific recommendations:

Intraoral X-ray Units

• Voltage range: 60-70 kV
• Focal spot: 0.4-0.7 mm nominal size
• Exposure time: Below 1 second at 3.5-8 mA
• Collimation: Rectangular collimation reduces dose by over 60% compared to circular
• Positioning: Minimum 20 cm focus-to-skin distance using long collimators
• Film speed: E/F-speed films reduce dose by ≥50% versus D-speed

Panoramic/Cephalometric Units

• Restrict field-of-view to clinically relevant areas
• Always use pediatric modes when available (≥50% dose reduction)
• Employ wedge filters and asymmetric collimation when appropriate
• Use fastest compatible screen-film combinations (≥400 speed)

CBCT Systems

• Select smallest appropriate FOV (≤6×6 cm for small FOV)
• Optimize kV/mAs settings per clinical indication and patient size
• Use high-resolution modes (<0.2 mm voxels) for trabecular bone imaging
• Consider reduced projection protocols when diagnostically acceptable

Digital Receptors: Dose Implications

While digital intraoral systems (CCD/PSP) offer dose reduction potential, improper use may increase exposure. Common pitfalls include unnecessary high-quality settings, undetected retakes, and inadequate collimation. Smaller sensors may require multiple exposures to cover areas imaged by single films.

Quality Assurance Protocols

Radiographs must meet diagnostic standards to justify radiation exposure. The European Guidelines on Radiation Protection in Dental Radiology provide quality benchmarks, recommending ≤10% unacceptable images. Regular audits should target 50% reduction in suboptimal radiographs per review cycle.

Intraoral Quality Control

Step-wedge test tools help maintain consistent image quality. Reference radiographs should be created during installation using optimized exposure settings, with periodic comparisons during clinical use.

Panoramic Optimization

Accurate patient positioning and proper film handling are critical. Dedicated test tools and thorough training improve outcomes.

Cephalometric Techniques

Dedicated cephalometric attachments ensure proper alignment. When using dental units as radiation sources, precise collimation and fixation are essential.

Transitioning to Digital Imaging

Increased retake rates may occur during digital adoption due to positioning errors and smaller receptor sizes. Beam-aiming devices and regular quality audits help mitigate this.

Immediate Dose Reduction for Older Units

For high-dose legacy systems, implement these temporary measures:

• Upgrade to E-speed film
• Add 1.0 mm aluminum filtration (requires technical assistance)
• Maintain existing exposure settings unless quality deteriorates
• Optimize film processing conditions

These steps may reduce doses by ≥70% pending equipment replacement.