結合單平面動態X光及電腦斷層攝影量測下顎之三維運動

Measurement of the Kinematics of Mandible Using Single Plane Fluoroscopy and Cone Beam CT

黃鈞郁(Chun-Yu Huang)

指導教授 ： 陳韻之

共同指導教授 ： 呂東武

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01030

摘要

下顎運動學的研究發展伴隨著量測記錄下顎運動的技術而演進，由傳統單平面，多平面的運動軌跡量測進步到三度空間六個自由度的立體量測。然而，要將量測結果與下顎骨電腦模型結合分析下顎動作時顳顎關節或骨體的空間位置變化常需要架設目標框架於下顎以利於記錄空間位置，目標框架的體積及重量會對下顎自然的生理運動造成干擾，使得所測的的結果客觀性受到質疑。

本研究目的為應用單平面動態X光立體量測技術，將之應用於下顎運動的動作分析研究，建立一個不須架設目標框架，高精確度的立體量測技術。實驗所使用的實驗儀器為牙科錐狀光束電腦斷層掃描系統，以及此系統所含的動態X光攝影模式。實驗所用試體為仔豬的頭部，取其與成人相近的下顎大小作為體外實驗樣本。於試體上下顎齒間隙固定直徑3公厘之水晶球作為照射時的標記點。試體先進行電腦斷層攝影建立標記之立體模型，隨後進行動態X光攝影取得測試動作的平面影像。利用校正實驗取得動態X光的校正參數來模擬動態X光之射源相對於感光板之幾何關係，於模擬系統中投射於標記點立體模型，將模擬的標記點投射影像與動態X光影像上實際的標記點位置做最佳化運算，當模擬投影點與影像平面上的標記點位置契合時，可得標記點空間位置的估計值。標記點空間位置再與電腦斷層掃描所得的實驗黃金標準值做比對，比對結果用做量測方式的誤差分析。

實驗結果顯示利用牙科錐狀電腦斷層系統及動態X光模式進行下顎動作的立體量測有良好的精確度，此一不須架設框架的量測技術可應用於其他牙醫學的相關研究，如活動義齒的穩定度量測。本實驗所建立的研究平台可對下顎運動六個自由度的記錄提供客觀的量測方式。

關鍵字

動態X光攝影 ； 下顎運動 ； X光立體量測

並列摘要

Introduction: Recording all 6 degree-of-freedom (DOF) is an essential requirement to study the complete mandible rigid body kinematics. However, most of the instrumentations available need trans-oral components, which might interfere the physiological jaw movements, to hold the signal senders. A new 2-D/3-D registration technique has been successfully applied to study the kinematics of knee joints and spines, etc. by using single-plane fluoroscopy and CT without any additional markers. The aim of this study was to evaluate the possibility of applying such technique to study the kinematics of the complicated constructed mandible.

Materials and Methods: A porcine head with complete dentition with radiopaque crystal beads attached to the teeth in the embrasure regions was scanned with conebeam CT to yield the 3D virtual model. Single-plane fluoroscopy was used to record the simulated mandible opening movements driven by a simple hydropumping device. Based on the pre-requisite of pointed x-ray source of the conebeam CT/fluoroscopy unit, the projected 2D mandible and marker beads shown on the single-plane fluoroscopy can be derived from the 3D model through a function of projection. Therefore, the spatial information of jaw position that produced best-matched projection with the fluoroscopic image was used to estimate the mandible rigid body motion.

Results: The tissue contrast shown on the fluoroscopy is too blurred to identify the detail of the mandible projection. However, the crystal marker beads can be easily identified and used as reference to bridge the CT and fluoroscopic images. By using the marker beads, the 2D/3D registration technique can yield a high precision movement recording with error limited within 0.12 degrees and 0.66 mm for rotation and translation, respectively.

Conclusion: This in vitro study has demonstrated that mandible rigid body kinematics can be precisely measured without trans-oral components by using single-plane fluoroscopy.

並列關鍵字

fluoroscopy ； RSA ； mandibular movement ； cone beam CT

參考文獻

• 蔡宗遠,“結合動態X光及電腦骨骼模型量測正常人與前十字韌帶缺損患者之膝關節三維運動”, 國立台灣大學醫學工程學研究所碩士論文, July 2004

• 陳健誌,“正常顳顎關節之開閉口運動分析 ”, 國立台灣大學臨床牙醫學研究所碩士論文, July 2004

• Baltzopoulos, V., 1995. A videofluoroscopy method for optical distortion correction and measurement of knee-joint kinematics. Clinical Biomechanics 10, 85-92.

• Berry H, Hofmann FA. Cinefluorography with image intensification for observing temporomandibular joint movements. JADA 1956; 53: 517-27.

• Doundoulakis J. H., Eckert S. E. , Lindquist C. C., Jeffcoat M. K. The implant-supported overdenture as an alternative to the complete mandibular denture JADA, 2003;134: 1455-8