臺灣博碩士論文加值系統

本研究的目的是在探討聚焦型超音波在不傷害甲狀腺以外的正常組織及不引起皮膚燒灼的條件下，治療甲狀腺腫瘤的可能性以及作妥善的術前規劃評估。單一晶片超音波換能器應用在模擬及體外實驗之中，其開口直徑3.5公分、曲率半徑5.5公分，頻率4MHz。模擬中探討不同的輸入功率、表面冷卻、加熱及冷卻時間來估算焦斑形成的大小，以及皮膚及前場溫升的情況。此外，為了更進一步避免皮膚燒灼及縮短焦斑長度，模擬中也將探討不同換能器的直徑及曲率半徑對聲強分佈及焦斑形成長度的影響。結果顯示，低於10W的輸入功率及高於10秒的加熱時間可以控制焦斑長度在約1公分之內，在此參數之下，40秒的冷卻時間足夠讓皮膚及前場的溫度回降。而在設計換能器方面，直徑4.375公分，曲率半徑3.5公分的換能器在降低皮膚溫度及縮短焦斑長度上的確有明顯的效果。本研究結果確認了聚焦型超音波應用在甲狀腺腫瘤治療上的可能性。以模擬及體外實驗結果所建議的參數將可讓焦斑集中在目標區域中而不傷害區域外的組織。

The purpose of this study is to investigate the feasibility of using high intensity focused ultrasound(HIFU) to treat thyroid nodules tissue without overheating surrounding normal tissues or inducing skin burn . A single element transducer (diameter 3.5cm、radius of curvature 5.5cm and frequency 4MHz) was used in simulation and in-vitro experiment study . Various input power、precooling、water temperature、sonication time and cooling interval among sonications were investigated to evaluate the lesion formation and temperature elevation. Furthermore, the intensity and thermal dosage distribution of different parameters ultrasound transducer was studied for the purpose of avoiding skin burn and shortening the lesion length. Results indicate that the input power lower than 10W and heating time longer than 10 seconds can produce a lesion within 1cm , 40 seconds cooling time is sufficient to cool down the temperature in front of the lesion. A diameter 4.375cm and radius of curvature 3.5cm transducer is suitable to produce a short lesion with low skin temperature elevation. The simulation and experiment study confirmed the feasibility of using HIFU to treat thyroid nodules , a target area can be treated safely without overheating the surrounding normal tissues by the input power and heating time suggested by the simulation and the in-vitro experiments.

第一章 緒論 1
1-1熱治療歷史回顧 1
1-2超音波熱治療淺層腫瘤 2
1-3甲狀腺結節傳統治療方式 3
1-4 研究動機 4
1-5 研究目的 5
第二章 理論分析與模擬方法 6
2-1波動方程式 6
2-2雷利-薩瑪菲爾德繞射積分式(RAYLEIGH-SOMMERFELD DIFFRACTION INTEGRAL) 6
2-3介質的能量衰減與吸收 8
2-4多層介質之壓力場模擬 9
2-5波源表面的壓力場 12
2-6壓力場模擬 12
2-7溫度場 15
2-8熱劑量 15
2-9 模擬參數 18
2-9-1 加熱功率及加熱時間 18
2-9-2 冷卻水對改善皮膚過熱 18
第三章 實驗方法 21
3-1 實驗設備 21
3-2 實驗材料 21
3-2-1實驗設置 23
3-2-2仿體製作 23
3-2-3 離體(in-vitro)組織 24
3-3 實驗參數 26
第四章 模擬結果 27
4-1換能器A - 單次加熱輸入功率選擇 27
4-2換能器A - 冷卻水改善皮膚過熱結果 29
第五章 實驗結果 32
5-1不同加熱功率及時間 32
5-2相同能量下所形成的焦斑形態 38
5-3表面冷卻對焦斑形成之影響 40
5-4焦點及近場之降溫速度 41
第六章 換能器設計 43
6-1設計結果 43
6.2換能器E加熱後結果 46
第七章 討論 49
7-1 輸入功率及加熱時間 49
7-2 冷卻對改善皮膚及前場過熱 50
7-3 相同能量 50
7-4 換能器設計 51
7-5 熱劑量、溫度與焦斑分佈關係 51
第八章 結論與未來展望 52
參考文獻 53

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