超導生物磁粒子造影系統最佳化特性研究

Abstract

本研究於電磁波屏蔽室內建立一座超導量子干涉元件之磁性粒子造影系統，目前已得知磁性奈米粒子具有良好的生物相容性，且經由表面修飾後可具有與特定抗原專一性結合的特性，因此具有影像顯影及癌症標靶等應用潛力。在訊號偵測的部分，選擇三倍頻訊號用來避開生物反磁性訊號；在影像取得部分，此系統使用三維度步進馬達移動樣品進行掃描以獲得磁流體的磁訊號分布圖。為了將磁流體磁訊號與定位點磁訊號作出區別，另繞製線徑為 0.3 mm 、內徑為 10 mm 、共 10 匝的定位線圈共四顆當作定位點，同時給予定位線圈不同的頻率，藉由輸出頻率的差異，得以在後續將小鼠體內磁流體與定位點磁訊號明顯分開以利之後分析。本系統包含了激發線圈、接收線圈與超導量子干涉元件，藉由繞製多組接收線圈匝數與所串聯之反向線圈的匝數後，調整兩線圈之間距離至訊號測得最靈敏位置，即得以將系統背景雜訊降至最低，而經過後續研究數據得知本磁通轉換器最佳參數為接收線圈使用線徑為 0.2 mm 、內徑為 8 mm 、每層 20 匝共 140 匝，反向線圈使用線徑為 0.2 mm 、內徑為 8 mm 、每層 40 匝共 170 匝，此參數不但雜訊強度較低，且電壓磁場轉換比效率也相對較高。透過後續掃描磁流體之序列稀釋、排列不同圖案和在小鼠體內施打不同濃度之磁流體的影像也證實了此項研究結果。因此現階段系統比過去擁有更高靈敏度功能性檢測的優勢，未來更可被用於腫瘤(癌)細胞影像顯影及追蹤等，以證明磁性奈米粒子於生物相關醫學成像應用的可行性。In this study, a magnetic particle imaging system with superconducting quantum interference device (SQUID) was established in an electromagnetic shielded room.In the signal detection part, the third harmonic signal is selected to avoid the bio-logical diamagnetic signal. In the image acquisition part, the system uses a three-dimensional stepper motor to move the sample to scan to obtain the magnetic signal distribution map of the magnetic fluid. In order to distinguish the magnetic signal of the magnetic fluid from the magnetic signal of the positioning points, another four positioning coils are used as the positioning points, and give the positioning coil dif-ferent frequencies at the same time. Due to the difference of the output frequency, the magnetic fluid in the mice body and the magnetic signal of the positioning point can be clearly separated for subsequent analysis.This system includes excitation coil, receiving coil and SQUID. The sensitivity of the system is improved by winding the receiving coils with different parameters, and the optimal experimental parameters are obtained through the voltage-magnetic field conversion ratio and the background noise intensity. The findings were also con-firmed by subsequent scans of phantoms and images of mice administered different concentrations of magnetic fluid.Therefore, the current system has the advantage of higher sensitivity than the past, and can be used for image development and tracking of tumor (cancer) cells in the future to prove the feasibility of magnetic nanoparticles in biological-related medical imaging applications.