Development of 10 principles of radiation protection in oral and maxillofacial radiology

Abstract

Purpose

This study aimed to establish an expert consensus on a set of principles for radiation protection in oral and maxillofacial radiology in Korea. Although national and international guidelines exist, their practical application to dental radiology remains limited, with key clinical components not subject to mandatory enforcement. Therefore, guidelines tailored specifically to dental radiology are necessary to ensure consistent and effective radiation safety.

Materials and Methods

A modified Delphi method was utilized, involving 20 experts—7 specialists in oral and maxillofacial radiology and 13 in medical radiology. A Guideline Development Committee initially drafted the principles, which were refined over 3 rounds of email-based surveys. Panelists evaluated each principle using a 9-point Likert scale, with quantitative scores and qualitative feedback informing the revision process.

Results

Consensus was reached on 10 principles, addressing radiographic justification, imaging scope limitations, pregnancy considerations, pediatric optimization, portable radiography, radiation dose monitoring and equipment operation. Final agreement scores approached 9.0, with standard deviations ≤0.7, confirming strong expert consensus.

Conclusion

The finalized principles constitute a structured, evidence-based guideline aligned with international standards while addressing specific challenges unique to oral and maxillofacial radiology. They offer practical strategies to enhance patient safety and standardize radiographic decision-making. Further research should investigate their clinical implementation and recommend periodic updates to reflect evolving technologies.

Introduction

Medical and dental radiation—the controlled use of artificial ionizing radiation for diagnostic imaging, treatment, and health screening—has become an integral component of modern healthcare. Leading international organizations such as the International Atomic Energy Agency (IAEA) and the International Commission on Radiological Protection (ICRP) emphasize the core principles of justification and optimization to ensure patient safety. These principles underpin global frameworks including the Bonn Call for Action (2012) and the International Basic Safety Standards (2014).1,2

The principle of justification requires that any exposure to radiation yield a net clinical benefit, ensuring that only necessary examinations are performed. However, practical application can be challenging, as it demands balancing clinical autonomy with regulatory oversight. Enhancing professional education, improving patient communication, and strengthening informed consent processes are essential to promote appropriate radiographic decision-making. Developing and implementing structured clinical guidelines and conducting regular clinical audits further support the appropriate utilization of radiographic examinations.3

In parallel, the principle of optimization seeks to minimize radiation exposure while maintaining diagnostic quality, adhering to the "As Low As Reasonably Achievable" (ALARA) principle. Optimization involves selecting appropriate imaging techniques, adjusting exposure parameters, and employing shielding-particularly for vulnerable populations such as children and pregnant patients.4,5,6 In dental radiology, evidence-based guidelines for cone-beam computed tomography (CBCT) have been developed to assist clinicians in limiting unnecessary radiation exposure while preserving diagnostic adequacy.7

Given the frequent use of ionizing radiation in dental imaging, strict adherence to justification and optimization is critical for patient safety. Together, these principles aim to enhance diagnostic outcomes while reducing radiation risks. Therefore, developing a concise, evidence-informed clinical framework is essential for standardizing clinical decision-making and supporting consistent radiation protection practices.4,5

Despite the availability of international and national radiation protection guidelines, many are overly complex or insufficiently tailored for routine dental practice. In South Korea, although foundational principles are institutionally established, their application to dental radiology is limited. Specific areas, such as the use of portable radiographic devices, have been addressed in national safety standards8 but are not always enforced as mandatory, leading to inconsistent implementation. This variability underscores the absence of widely adopted clinical guidelines tailored specifically to oral and maxillofacial radiology.

To address this gap, the present study aimed to develop a consensus-based set of concise, clinically applicable principles for radiation protection in oral and maxillofacial radiology in Korea. Using a structured Delphi process involving experts in both dental and medical radiology, this study sought to establish a practical framework aligned with global standards that addresses local clinical needs. These principles aim to guide clinical decision-making and promote consistent, evidence-informed radiation protection standards in dental radiology.

Materials and Methods

Guideline Development Committee and literature review

To establish a robust framework for radiation protection in oral and maxillofacial radiology, a Guideline Development Committee was formed, consisting of 3 specialists with over a decade of experience in radiology research, clinical practice, and national radiation safety policy. Selection prioritized individuals with notable contributions to peer-reviewed publications, international conferences, and national radiation safety protocols. The committee performed a comprehensive review of both domestic3,7,8,9,10,11 and international radiation protection guidelines, including materials from the Korean Academy of Oral and Maxillofacial Radiology (KAOMFR), relevant national regulations, and frameworks from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), the World Health Organization (WHO), IAEA, and the United States Environmental Protection Agency (US EPA).4,6,12,13,14,15,16,17,18,19,20 By synthesizing these authoritative sources, the committee aimed to develop evidence-based recommendations specifically tailored to dental radiology, considering feasibility, regulatory alignment, and clinical implementation.

Draft principle formulation and evaluation criteria

The development process was structured around 5 core questions: What are the biological effects and risks associated with radiation exposure? What clinical procedures should precede radiographic examinations? What conditions must be satisfied before conducting radiographic examinations on asymptomatic adult patients? How should radiation safety be managed for healthcare personnel exposed to radiation? What information is necessary for informed patient decision-making regarding radiographic procedures?

These questions formed the conceptual framework for drafting the principles. The Guideline Development Committee undertook a structured review of key international and domestic radiation protection guidelines to develop an initial draft. Each committee member independently assessed documents from leading regulatory and scientific organizations.1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,21,22,23,24,25 Four criteria guided the formulation of actionable draft principles: scientific validity, clinical relevance, implementation feasibility, and adaptation to local regulations. Scientific validity was evaluated based on alignment with internationally recognized guidelines from WHO, IAEA, and UNSCEAR. Clinical relevance concerned each principle's direct impact on radiographic decision-making and patient safety, particularly regarding CBCT justification and pediatric imaging. Feasibility focused on integrating principles into Korean dental practice, including portable radiography protocols, informed consent, and operator training. Adaptation ensured conformity to Korea's regulatory context, specifically the Ionizing Radiation (Medical Exposure) Regulations (IR(ME)R), Ministry of Health and Welfare (MOHW) guidelines, and KAOMFR standards. Through structured discussions, redundant items were eliminated, and content was refined for clarity and clinical applicability. Initially, a formal scoring system was considered, but a qualitative, consensus-based approach was ultimately adopted to best reflect expert judgments. Given the complexity and variability in dental radiation practices, this flexible yet structured method supported drafting 10 preliminary principles for evaluation through the Delphi process.

Delphi consensus process

A modified Delphi technique was employed, utilizing structured, email-based surveys where experts evaluated predefined draft principles. Unlike the traditional Delphi method, which begins with open-ended item generation, this approach started with researcher-developed statements, applying predefined criteria for revisions and consensus assessment. This iterative method is widely accepted for establishing expert consensus, especially in areas lacking formal guidelines or undergoing rapid development.26,27

An expert panel of 20 individuals was convened, including 7 specialists in Oral and Maxillofacial Radiology and 13 in Medical Radiology. Panel selection criteria included over 10 years of professional experience in radiology research or clinical practice, participation in national radiation safety protocol development, and authorship in peer-reviewed publications and conference presentations. Panelists rated each principle on a 9-point Likert scale (1–3: low agreement, 4–7: moderate agreement, 8-9: high agreement) and provided qualitative feedback to enhance clarity and practicality.28,29 Statements with a score below 7 from any respondent were revised and reassessed in subsequent rounds.

Final round and principle refinement

Three Delphi rounds were conducted between September and October 2023, with 3-week intervals. Responses were electronically submitted via email, and the expert panel composition per round is summarized in Table 1. Seventeen experts participated in the first round, including 7 specialists in oral and maxillofacial radiology (OMR) and 10 in medical radiology. In the second round, 14 experts responded (13 from the initial round and 1 new respondent), comprising 7 OMRs and 7 medical radiologists. In the final round, participation included 8 experts—6 OMRs and 2 medical radiologists. Despite reduced response rates, consensus on all 10 principles was achieved by the conclusion of round 3. After each round, committee members reviewed responses and revised the principles to address any items exhibiting high variability or requiring clarification. Table 2 presents the progression of agreement scores and variability across rounds. Principles showing significant variability were refined based on quantitative outcomes and qualitative input, improving phrasing, scope, and structure for increased clarity and practical relevance.

Table 1. Expert panel response rate across Delphi rounds.

n: number of respondents; N: number of invited experts.

Table 2. Consensus scores for summarized Delphi statements across 3 rounds.

All values are shown as range (min–max) and mean ± SD. Min: minimum score; Max: maximum score; SD: standard deviation. Final item numbers reflect the consensus-based order from round 3.

The final scores indicated consistently high agreement (mean scores ≥7 and standard deviation (SD) ≤0.7), validating the Delphi process outcomes. This structured approach facilitated the development of 10 consensus-based principles specifically tailored to oral and maxillofacial radiology, ensuring both scientific rigor and practical applicability.

Results

Development of the draft and the Delphi process

The Guideline Development Committee developed an initial set of 10 draft principles based on key international and domestic guidelines. These served as the baseline for round 1 of the Delphi process. The principles and their sub-items, reflecting the original expert-developed Korean version used during the initial Delphi round, are fully listed in Table 3.

Table 3. Initial draft principles and sub-items for Delphi round 1.

A 3-round Delphi method was employed to achieve expert consensus. The overall process, from initial drafting to final agreement, is illustrated in Figure 1. Each round integrated expert feedback and scoring, with specific revisions informed by quantitative scores and qualitative comments. Three Delphi rounds were completed, with response numbers declining from 17 to 8 across the rounds. Expert feedback and agreement scores formed the basis for revising and finalizing the principles. Items that failed to achieve high consensus, particularly those with lower agreement scores or high standard deviations, were reviewed by the Guideline Development Committee to refine their wording and structure. Each subsequent round incorporated modifications to individual principles or sub-items based on expert input. Consistent responses and high agreement levels confirmed the validity and clinical applicability of the final principles. The process began with the initial draft, followed by iterative refinement steps. Final consensus was confirmed with all scores ≥7 and SD ≤0.7, meeting the predetermined threshold. Therefore, additional Delphi rounds were unnecessary. Table 2 summarizes consensus scores for each principle across Delphi rounds. The first column indicates item numbers from rounds 1 and 2, while the final numbers reflect the reordered structure established after round 2, which was used in round 3. Summarized consensus statements across Delphi rounds appear in Table 2 for brevity. Revisions informed by expert feedback are detailed in narrative form below, illustrating the evolution of the draft principles, and supplemented by Tables 4 and 5, summarizing revisions following rounds 1 and 2, respectively. The finalized consensus-based principles, incorporating all iterative modifications, are presented in Table 6.

Fig. 1. Workflow of the 3-round Delphi process used to finalize radiation protection principles in oral and maxillofacial radiology.

Table 4. Principles revised following round 1 for round 2 (Unmodified principles from the initial draft are not shown).

Table 5. Principles revised following round 2 for round 3 (Unmodified principles from the initial draft are not shown).

Table 6. Final 10 principles.

Revisions across Delphi rounds

After round 1, feedback and consensus scores indicated several items required revision due to high standard deviations and specific panel comments. Item 5 was revised for greater clinical applicability and flexibility, item 8 was clarified by removing redundancy, and item 10 was expanded to include specific operator training details, particularly regarding radiation safety officer responsibilities. These revised statements, which are summarized in Table 4, were incorporated into the second-round evaluation to enhance clarity and practical relevance.

In round 2, further modifications improved alignment with clinical practice. The principle addressing radiographic examinations during pregnancy was reassigned as item 2 to highlight its clinical significance. The portable radiographic device principle, initially item 5, moved to item 3 and was revised to initially remove the restrictive term "only," allowing broader interpretation. However, in round 3, panelists advocated stricter limitations, prompting the reintroduction of "only" to reinforce safety requirements. The patient dose monitoring principle, initially item 9, was reassigned as item 7 due to its safety and compliance significance, while the previous item 7 shifted to item 9 for logical consistency. Item 4 (initially item 2), addressing radiation exposure minimization, was revised to emphasize placing the X-ray tube head closer to the patient's skin rather than merely using collimation devices. Item 6, on portable device safety, was expanded with 3 specific sub-recommendations. Item 8 was revised again, and while the previously considered criterion—namely, that the proportion of diagnostically unacceptable images should not exceed 10%—was excluded during round 2 for simplification, it was reinstated in round 3 based on expert feedback emphasizing quality assurance and reduction of repeat exposures, as summarized in Table 5.

During round 3, only minor linguistic edits were made to ensure consistency. The term "only," which had been removed from the sub-item under the portable intraoral radiography principle in round 2 to allow interpretive flexibility, was reconsidered based on panel concerns regarding stricter control. However, this restrictive phrasing was ultimately excluded from the final consensus statements to preserve broader clinical applicability. Additionally, the previously excluded sub-item under item 8—"the proportion of diagnostically unacceptable images should not exceed 10% to minimize repeat exposures"—was reinstated in response to expert feedback emphasizing image quality assurance. However, to avoid over-constraining clinical applicability and allow flexibility in quality control metrics, this criterion was ultimately excluded from the final consensus statements. These revisions ensured the final 10 principles were clearly articulated, clinically relevant, and aligned with oral and maxillofacial radiology best practices. The fully detailed final statements appear in Table 6, encapsulating the structured Delphi process outcomes.

Final consensus and summary

By the conclusion of round 3, all principles reached the predefined consensus threshold, indicating strong expert agreement. As further revisions were unnecessary, the process concluded with minor linguistic refinements to ensure clarity and consistency.

To enhance transparency regarding the integration of expert feedback, revisions made during rounds 2 and 3 are summarized in Table 4 and Table 5, respectively. These tables document only those principles that underwent substantive modifications, based on panelist comments related to clarity, feasibility, and clinical relevance. Principles that remained unchanged across the Delphi rounds are not repeated. All revisions were grounded in the initial draft principles listed in Table 3, which served as the foundation for round 1 evaluation.

The final 10 principles, refined through structured consensus, provide an evidence-based framework for enhancing radiation safety in oral and maxillofacial radiology. They address critical areas, including justification, dose limitation, pediatric and pregnancy-specific protocols, portable device use, quality assurance, and operator responsibilities. Table 6 presents these finalized principles comprehensively, serving as a standardized reference for clinical practice.

Discussion

This study developed a set of 10 consensus-based principles, collectively functioning as a clinical guideline for radiation protection in oral and maxillofacial radiology. Using a structured Delphi process, expert consensus was established, ensuring each principle's clinical relevance, feasibility, and practical applicability. Instead of providing isolated recommendations, the resulting framework offers a coherent and standardized foundation for consistent decision-making in dental radiology.

Despite the presence of national and international guidelines, their direct relevance to oral and maxillofacial radiology is limited. Key areas such as portable imaging, pediatric dose control, and quality assurance are often overlooked in general frameworks. This challenge is exacerbated by the increasing complexity of dental imaging technologies. The proposed guideline addresses these limitations through content tailored to the specific needs and operational realities of dental radiology in Korea, as shown in prior efforts to develop local clinical criteria30 and in surveys of Korean dentists' perceptions on radiation safety and selection protocols.31

Initially, a quantitative scoring method was considered during preliminary item development. However, the Guideline Development Committee opted for a qualitative, consensus-based review during the initial phase to better capture clinical judgment. Subsequent rounds employed structured quantitative evaluations using a 9-point Likert scale to guide iterative refinements.

The Delphi method effectively incorporated expert feedback across 3 rounds. Revisions during rounds 1 and 2 focused primarily on enhancing clarity, feasibility, and alignment with clinical realities, particularly for items 2, 5, 6, 8, and 10. In Round 3, the wording of all ten principles was finalized, achieving high agreement scores (mean approaching 9.0; minimum ≥7.0) with reduced standard deviations (≤0.7), thus meeting the predefined consensus threshold. Although panelist participation decreased over the rounds, most oral and maxillofacial radiology experts remained involved throughout. Crucially, all panelists providing lower agreement scores in round 2 continued into round 3, ensuring their insights were incorporated into the final version. Specific refinements during the Delphi process—such as the debated use of the term "only" under portable radiography, the inclusion and later removal of a 10% threshold for diagnostically unacceptable images, and the reordering of items 7 and 9—highlight the panel's emphasis on practical applicability. These iterative changes, supported by numerical indicators in Tables 3 through 6, illustrate the depth and transparency of the consensus-building process.

The finalized 10 principles constitute a practical, evidence-based guideline aligned with the ALARA framework. They stress clinical justification, optimization of imaging parameters, and dose limitation. Implementation strategies include limiting the field of view, reviewing previous radiographs, employing collimation, and adjusting exposures for pediatric and pregnant patients. These elements collectively promote patient safety and diagnostic quality.

Future research should investigate methods for integrating these principles into daily clinical workflows and evaluate their effects on clinician behavior, patient safety, and diagnostic accuracy. While this study focused on establishing clinical principles for radiation protection, it did not address certain procedural or technical aspects—such as using tripods or remote activation for portable devices—which warrant further investigation to ensure comprehensive and safe practical implementation. A notable feature of these guidelines is the emphasis on portable radiographic devices, reflecting their increasing prevalence in dental practice. Specific recommendations include guidelines for focal-spot-to-skin distance, backscatter shielding, and operator protection, reinforcing essential elements within existing frameworks to support practical implementation in dental settings. Comparative studies with international standards could further support global harmonization in dental radiation protection, and practical clinical implementation may enhance adherence and consistent application.

As dental imaging technology continues to evolve, periodic updates to this guideline will be essential for maintaining clinical relevance. Collectively, this evidence-based framework serves as a standardized reference, promoting safe and effective radiographic decision-making in oral and maxillofacial radiology.