應用於磁振造影導引聚焦式超音波腦腫瘤治療之三維定位系統

A Three-dimensional Positioning System Applied in MRI-guided Focused Ultrasound Thermal Therapy for Brain Tumors

郭晟恩(Cheng-En Guo)

指導教授 ： 林文澧

共同指導教授 ： 陳景欣(Gin-Shin Chen)

國立臺灣大學/工學院/醫學工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201902295

摘要

本研究的目標為研發出應用於磁振影像導引腦腫瘤治療之承載MR 相容聚焦式超音波換能器的三軸定位平台。利用磁振造影(Magnetic Resonance Imaging, MRI)結合高強度聚焦式超音波(High Intensity Focused Ultrasound, HIFU)做超音波熱手術，可以在診斷的同時做精準的導引與治療；其治療方式具有非侵入式的優點，並可進一步結合溫度影像及搭配其他治療方式增進其診斷治療效果。
本研究使用聚甲醛(POM)材料製作運動平台的本體，並運用手動旋轉方式藉由螺桿螺母搭配帶動平台進行移動，本移動機構一共具有X、Y、Z 三個自由度及一個旋轉，X、Y分別各有50mm 的移動行程，Z方向也有50mm的移動行程，而換能器所能旋轉的最大角度為30度。搭載球狀陣列式超音波探頭時，由於超音波傳遞需要有水當介質，實驗時會使用去氣水裝滿球狀超音波探頭，並裝置於本實驗所研發的三軸定位平台上；在平台設計上的所有的機構及零組件將以MR 相容的材料製成，選用材質包含POM、PLA、銅合金、鋁合金、壓克力等，並利用磁相容光學尺回授平台移動位置。本實驗所使用的為國衛院3T MRI，在此特殊的環境條件，在材料選用上均為非磁性及空間受到限制下設計製造MR 相容之三軸定位平台，對於工程師來說是一項挑戰。
平台建構完成後，以光學尺對搭載球狀陣列式換能器之三軸定位平台之定位功能進行精準度測試，其誤差在經過校正後均小於250μm，並經過MRI 取像測試後，初步判斷其具有足夠的MR 相容性，並不會對操作人員產生安全上的危害，亦不會對MRI 取像造成干擾，且能確實地將球狀陣列式超音波換能器完成移動定位工作。
本研究針對MRI 造影系統，開發出適用於腦腫瘤超音波熱手術之三軸定位平台。此系統有足夠的定位精準度及MR 相容性，應可有效承載球狀陣列式超音波換能器進行腦腫瘤熱手術。

關鍵字

MRI ； 三維定位系統 ； 磁相容光學尺 ； 腦腫瘤 ； 磁振造影導引聚焦式超音波 ； POM

並列摘要

The purpose of this study was to develop a three-dimensional(3-D) positioning system for MR-compatible focused ultrasound transducers with magnetic imaging guided for brain tumor therapy. Using Magnetic Resonance Imaging (MRI) combined with focused ultrasound for brain thermal therapy, and hence it can be used for precise guidance and treatment simultaneously. It is a non-invasive therapy, and can be combined with temperature imaging and nanodrugs to improve its diagnosis and treatment.
In this study, polyoxymethylene (POM) material was used to make the positioning platform, which was moved by a screw nut in a manual rotation mode. The positioning platform has three degrees of freedom , and one rotation, and the movement rang of X,Y and Z is 50 mm, and the maximum angle of rotation is 30 degrees. When using a spherical array of ultrasonic transducers,the ultrasonic transducer is filled with degassed water and installed in the 3-D positioning platform ; The positioning platform is made of MR compatible materials, including POM, PLA, copper alloy, aluminum alloy, acrylic, etc., and with an MR compatible scale tape feedback . NHRI 3T MRI system was used and it was a challenge to design and manufacture MR-compatible 3-D positioning platforms with non-magnetic materials and limited space constraints.
The MRI compatibility optical scale is tested for the accuracy of the movement function of the 3-D positioning platform with the spherical array transducer, and the error is less than 250 μm after correction. The results of MRI imaging test, showed that it has sufficient MR compatibility and it would not interfere with the MR image. The platform could accurately perform the positioning work for the spherical array ultrasonic transducer.
In this study, a 3-D platform for brain tumor ultrasound thermal therapy was developed with the MRI system. This platform has considerable positioning accuracy and MR compatibility, and should be able to effectively carry a spherical array ultrasonic transducer for brain tumor thermal therapy.

並列關鍵字

MRI ； three-dimensional positioning system ； MRI compatible optical ruler ； brain tumor ； magnetic resonance imaging guided focused ultrasound ； POM

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