Investigating the effect of thyroid shields and lead glasses on image quality and artefacts in cone beam computed tomography devices: A phantom study

Introduction

The objective of this study is to investigate and compare the impact of thyroid shields and lead glasses on the image quality (IQ) and artefacts in dental Cone Beam CT (CBCT) images. The current study aims to evaluate the effectiveness of this protective equipment in enhancing the quality of dental CBCT images.

Methods

In this study, a New Tom dental CBCT device was used to scan Pro-Project phantom with and without thyroid shields and lead glasses in three different large, medium, and small Fields of View (FOVs). The several key IQ parameters such as noise, contrast-to-noise ratio (CNR), homogeneity, contrast-resolution (CR), and spatial-resolution (SR), were evaluated using ImageJ software. The measurements were performed and compared in various cross-sections based on the location of test objects in the phantom.

Results

The study found that the use of thyroid shields and lead glasses resulted in a decrease in CNR and homogeneity parameters, while noise increased. However, there were no significant changes in SR and CR. It should be noted that the use of thyroid shields and lead glasses may increase image noise by 1–7 %. The combined use of lead shields was not included in our findings, as their effects are localized and similar to separate evaluations in adjacent areas in lower and upper sections.

Conclusion

Thyroid shields and lead glasses during dental CBCT imaging increase image noise and reduce CNR. Proper placement is crucial, and reducing the FOV size can minimise artefacts while preserving diagnostic accuracy.

Implications for practice

Thyroid shields and lead glasses are vital for radiation protection. Increased noise demands attention in clinical practice. Ongoing research, training, quality assurance, and effective patient communication are essential for safety and trust in dental imaging.