| 摘要: | 環形檢測機制是目前較普遍的近紅外光擴散光學(near infrared diffuse optical imaging, NIR DOI)檢測機制，其檢測方式是將光源與光偵測器環狀排列在乳房周圍，擷取乳房內不同角度的光資訊用於光學係數影像重建。然而現有環形檢測機制的光源與光偵測器多設計為固定式光通道，無法順應受檢者乳房輪廓量測且影像重建的有限元素幾何模型並非受檢者真實的乳房輪廓，導致影像重建失真。因此本研究以兩種case的半橢球仿體模擬受檢者乳房垂置於檢測區的真實形狀，並設計一進一出掃描量測裝置( 1 Source , 1 Detector )與頻域式量測系統對半橢球仿體進行固定與彈性光通道掃描量測，量測光源使用830及785nm波長的雷射，雷射調變頻率以29.001MHz交流電源驅動，量測所得光資訊以本實驗室發展之光學係數影像重建軟體進行光學系數影像重建，並以根均方誤差(root mean square error, RMSE )評估影像品質，誤差越低代表重建影像與參考影像的越接近，為了降低吸收( Ua )及散射( Us’ )係數的數量級影響，以三種不同方式對根均方誤差值進行優化，經優化產生的 Error值(%)為本研究的影像品質評估方法，Error 值越低代表影像品質越好。
基於實驗結果顯示，在三種不同的Error值中比較，彈性光通道量測對於較易量測的高光學系數對比度( Ua , Us’ = 4 , 2 )大顆淺層腫瘤，Error( Ua )值最多降低約6%、Error( Us’ )值最多降低約1%以上，對於極難量測的低光學系數對比度( Ua , Us’ = 2 , 1 )小顆深層腫瘤，Error( Ua )值最多能降低約2%，因此證明無論腫瘤在淺層或深層位置及腫瘤的大小，彈性光通道量測皆能提高腫瘤特徵及降低重建影像與參考影像的誤差。而基於實驗結果之進步，設計彈性光通道機構裝置改良本實驗室的環形掃描機台的光通道，使其能順應受檢者乳房輪廓量測，消除檢測區域與乳房的間距，且在12個彈性光通道後端安裝光學式位移計用以估測計算受檢者乳房輪廓。
;Ring-scanning mechanism is currently common near infrared diffuse optical imaging (NIR DOT). However, sources and detectors of the existing ring detection mechanisms are mostly as fixed channels, cannot adapt to the breast contour of the subject, cannot adapt to the breast contour , aresulting in image reconstruction distortion. In this research, two cases of semi-ellipsoid phantoms are used to simulate the true shape and design scanning measurement equipment (1 Source 1 Detector) and frequency-domain measurement system for fixed and flexible optical channel scanning measurement of semi-ellipsoid phantom, source uses 830nm and 785nm lasers, source frequency uses 29.001MHz, the obtained optical information is reconstructed by the optical-property images reconstruction software developed by our laboratory, evaluate image quality witht in three different Error(%) , The Error is optimized by root mean square error ( RMSE ).
Shown by the experimental results, flexible optical channel measurement for large superficial tumors with high optical coefficient contrast( Ua , Us’ = 4 , 2 ), Error( Ua ) reduced by about 6% at most, and Error( Us’ ) reduced at most about 1% or more. For small deep tumors with low optical coefficient contrast( Ua , Us’ = 2 , 1 ), Error( Ua ) reduced by about 2% at most. Therefore, no matter location or size of the tumor, flexible optical channel measurements can improve tumor characteristics image reconstruction errors. Based on experimental results, design a flexible optical channel mechanism to improve the optical channel of the circular scanning machine in our laboratory. |
