光學同調斷層掃描術應用於牙⿒硬組織偵測之研究

Abstract

背景：齲⿒是全球最常見的⼝腔疾病之⼀，對患者的⼝腔健康和⽣活質量有重⼤影響。早期診斷和治療對預防齲⿒惡化⾄關重要。傳統X 光檢查雖能提供詳細影像，但存在輻射暴露和解析度有限的問題。光學同調斷層掃描術（Optical Coherence Tomography, OCT）是⼀種非侵⼊性、⾼解析度且無輻射的技術，已在眼科等領域取得成果。OCT能即時提供微（μm）級的⽣物組織斷層影像並⽣成三維圖像。儘管OCT在發明五年後即有商用機種，但在牙科領域仍主要停留在學研階段，顯示出其在牙⿒硬組織掃描上的挑戰，主要包括：(1)成像深度和品質受限於光學系統和牙⿒光學性質；(2)OCT影像對比度依賴牙⿒內部組織的光學特性分布，但牙釉菱柱和牙本質小管的線性排列會導致非等向性和雙折射效應。 研究目的：本研究旨在評估OCT在牙⿒硬組織和齲⿒檢測中的效果，並將其與其他成像技術（如X 光和錐狀射束電腦斷層掃描（Cone Beam Computed Tomography，CBCT））進⾏比較，以確定OCT在齲⿒診斷中的優勢和局限性。同時，研究還探索了使用⾼折射率液體（如甘油）提⾼OCT影像質量的⽅法，並研究多角度掃描和顏⾊映射技術在OCT影像中的應用，評估其對影像清晰度和診斷準確性的影響。此外，還使用OCT對⿒質厚度進⾏測量，以探討其準確性。期望OCT能夠為臨床牙科診斷提供更精確和有效的技術支持。 材料與⽅法：本研究收集了多個牙⿒樣本，並利用掃頻式光學同調斷層掃描系統（SSOCT）對其進⾏掃描。首先對牙⿒樣本進⾏清潔和編號，然後選取特定位置使用SS-OCT進⾏掃描。此外，記錄目視檢查、X 光檢查和CBCT的齲⿒檢測結果，以評估這些⽅法在齲⿒偵測中的準確性。影像優化實驗分為三個部分：第⼀，觀察塗抹甘油後影像的優化效果；第⼆，使用多角度影像合成技術，包括正面和左右旋轉5 度角的影像，並將這些影像與未塗甘油的影像及Micro CT影像進⾏比較；第三，嘗試使用顏⾊映射技術標記齲⿒病變區域，以提⾼影像的可視化效果。影像的比較以微米級電腦斷層掃描造影系統（Micro-CT）影像作為黃⾦標準，Micro-CT和OCT影像皆匯⼊Amira® 3D Pro（Thermo Fisher Scientific, USA）軟體進⾏3D 影像重組及資料分析。最後，使用SS-OCT系統測量⿒質厚度，以驗證其準確性和可⾏性，並使用Excel軟體中的資料分析功能進⾏統計分析並繪圖。 結果：研究結果顯示，OCT能夠清晰顯示齲⿒病變區域的結構特徵，在早期齲⿒偵測中具有較⾼的靈敏度和準確性。與X 光和CBCT相比，OCT在非侵⼊性診斷⽅面具有優勢，特別是在避免輻射暴露和提供更⾼解析度影像⽅面。使用甘油處理後，OCT影像的對比度和清晰度顯著提⾼，影像深度也有所提升。多角度掃描和影像合成技術增加了影像資訊，進⼀步提升影像品質。此外，顏⾊映射技術使得OCT影像中的齲⿒病變區域更加直觀且易於識 別。⿒質厚度測量結果顯示，⼿動測量與OCT測量數據具有⾼度的線性相關性，但當樣本厚度超過2mm時，⼿動測量值和OCT測量值之間的誤差明顯增⼤。 結論：OCT在齲⿒早期偵測中展現出巨⼤潛⼒，能夠提供無輻射、⾼解析度的牙⿒結構影像。與傳統X 光和CBCT技術相比，OCT在初期齲⿒診斷中具有更⾼的靈敏度和準確度，為臨床牙科提供了⼀種更安全、有效的診斷⼯具。使用甘油可進⼀步提⾼OCT影像品質，多角度掃描影像合成技術能增加影像資訊，提升影像的清晰度和對比度。顏⾊映射技術使齲⿒病變區域的可視化更加直觀。剩餘⿒質厚度的測量結果顯示了使用OCT測量⿒質厚度的可⾏性。未來的研究應著重於推廣OCT技術的臨床應用，並探索更多提⾼影像品質的⽅法。

Background: Dental caries is one of the most common oral diseases worldwide, significantly impacting patients' oral health and quality of life. Early diagnosis and treatment are crucial to prevent further deterioration. Traditional X-ray examinations, while providing detailed images, pose issues such as radiation exposure and limited resolution. Optical Coherence Tomography (OCT) is a non-invasive, high-resolution, and radiation-free imaging technique that has achieved significant success in fields like ophthalmology. OCT can provide real-time, micron (μm)-level cross-sectional images of biological tissues and generate threedimensional images. Although commercial OCT devices became available five years after its invention, its application in dentistry remains primarily at the research stage, highlighting challenges in scanning hard dental tissues. The main challenges include: (1) imaging depth and quality being limited by optical systems and the optical properties of teeth; (2) OCT image contrast relying on the distribution of optical properties within the tooth, with the linear arrangement of enamel prisms and dentinal tubules causing anisotropy and birefringence effects. Purpose: This study aims to evaluate the effectiveness of OCT in detecting dental hard tissues and caries, and to compare it with other imaging techniques such as X-rays and Cone Beam Computed Tomography (CBCT) to determine the advantages and limitations of OCT in caries diagnosis. Additionally, the study explores methods to enhance OCT image quality using high refractive index fluids (e.g., glycerin), and investigates the application of multi-angle scanning and color mapping techniques in OCT imaging, assessing their impact on image clarity and diagnostic accuracy. Furthermore, OCT will be used to measure dental tissue thickness to examine its accuracy. It is hoped that OCT can provide more precise and effective technical support for clinical dental diagnosis. Materials and methods: In this study, multiple tooth samples were collected and scanned using a Swept-Source Optical Coherence Tomography (SS-OCT) system. First, the tooth samples were cleaned and numbered, and then specific locations were selected for SS-OCT scanning. Additionally, visual examination, X-ray examination, and CBCT examination results were recorded to evaluate the accuracy of these methods in detecting caries. The image optimization experiment was divided into three parts: first, observing the optimization effects of images after applying glycerin; second, using multi-angle image synthesis techniques, including images from the front and 5-degree rotations to the left and right, and comparing these images with those without glycerin application and with Micro-CT images; and third, attempting to use color mapping techniques to mark caries lesion areas to enhance image visualization. The comparison of images used Micro-CT images as the gold standard. Both Micro-CT and OCT images were imported into Amira® 3D Pro (Thermo Fisher Scientific, USA) software for 3D image reconstruction and data analysis. Finally, the SS-OCT system was used to measure the thickness of the tooth structure to verify its accuracy and feasibility. Statistical analysis and plotting were performed using the data analysis functions in Excel software. Results: The research results indicate that OCT can clearly reveal the structural characteristics of carious lesions and has high sensitivity and accuracy in the early detection of dental caries. Compared to X-rays and CBCT, OCT has advantages in non-invasive diagnosis, particularly in avoiding radiation exposure and providing higher resolution images. After applying glycerin, the contrast and clarity of OCT images significantly improve, and the imaging depth is also enhanced. Multi-angle scanning and image synthesis techniques increase the amount of image information, further improving image quality. Additionally, the use of color mapping techniques makes the carious lesion areas in OCT images more intuitive and easier to identify. Measurements of tooth thickness show a high linear correlation between manual measurements and OCT data, but when the sample thickness exceeds 2mm, the discrepancy between manual measurements and OCT measurements increases significantly. Conclusion: OCT shows great potential in early caries detection, providing radiation-free, high resolution images of dental structures. Compared to traditional X-ray and CBCT techniques, OCT offers higher sensitivity and accuracy in the diagnosis of early caries, providing a safer and more effective diagnostic tool for clinical dentistry. The use of glycerin can further enhance the quality of OCT images. Multi-angle scanning and image synthesis techniques can increase image information, improving image clarity and contrast. The color mapping technique makes the visualization of caries lesions more intuitive. The results of measuring the dental tissue thickness demonstrate the feasibility of using OCT for this purpose. Future research should focus on promoting the clinical application of OCT technology and exploring more methods to improve image quality.