- 學位論文
週期性腫瘤運動之影像追蹤與超音波熱治療
High Intensity Focused Ultrasound Treatment and Image-based Tracking with Periodic Tumor Motion
摘要
超音波熱治療手術為一種非侵入式手術，利用機械波的震動與聚焦造成組織溫度的升高，而其中陣列換能器由於具備振幅與相位的可調性，其聚焦點可經由電子式控制而改變聚焦位置。以超音波熱治療時，必須準確地將熱劑量送至異常組織以避免造成對正常組織傷害。近年來，許多論文探討以核磁共振攝影引導超音波熱治療觀測溫升變化，透過影像可得知異常組織位置與溫度。 然而由於內臟器官會因呼吸所引起橫隔膜運動而帶動其做立體空間的運動，這些運動會導致超音波無法準確聚焦在目標區域上。同時在硬體方面無論影像系統或者是治療系統本身，都需要驅動時間與運算時間，所以系統延遲是必然的。因此必須以預測運算來減少聚焦點與目標物間之距離誤差，以達到熱劑量準確送達異常組織之目的。 本論文中，以CCD影像模擬醫學影像，利用馬達帶動平台運動模擬由呼吸所引起的內臟運動軌跡，再利用相位陣列換能器動態聚焦的能力對運動中的目標物進行追蹤加熱。透過簡易的系統架構，瞭解實務上將會遇到的問題，以利克服日後系統整合上的困難。
並列摘要
Image guidance in hyperthermia offers the potential for precise thermal dose delivery to a moving tumor. MR-Image guided ultrasound thermal therapy has been investigated in many studies recently. MR-Image offers not only the temperature field in the tissue but also the other information, for instance, perfusion…etc. Phased array transducer has the ability to change the focus position and patterns by tuning the phase and power per element on array transducer. The main system is to combine CCD image system used to simulate image acquired by medical image(MRI, Ultrasound Image, diagnostic x-ray imaging ) with HIFU(High Intensity Focus Ultrasound). Putting tissue on the movable plane controlled by servo-motor simulates the organ motion by respiration. To integrate motion system, image sensor and sonic-system is the main operation for solving "locked on target" through image detection. However, the delivery of a treatment plan through sonic beam tracking requires adequate consideration of treatment system latencies, including image acquisition, image processing, communication delays, control system processing, inductance within the motor, mechanical damping, etc. Regular respiratory motion fitted by Fourier series is ordered to overcome system delay.