適用於可攜式超音波影像系統之 智慧型彩色都卜勒數位信號處理引擎

Intelligent Color Doppler DSP Engine for Portable Ultrasound Imaging Systems

張凱婷(Kai-Ting Chang)

指導教授 ： 吳安宇

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.01262

摘要

超音波影像（ultrasonic imaging）因為有低成本、非侵入性（non-invasiveness）、即時成像、與儀器較方便攜帶等優點，所以是一種被廣泛使用的造影方式。而其中彩色都卜勒（color Doppler）影像是一種在醫學界被廣泛使用的超音波成像模式，係利用探頭和血流之間的相對運動以及夾角求出流速等資訊。其主要的價值在於它可以即時（real-time）地呈現出體內流速的二維影像，應用的對象包含血流及心搏等。然而，為了即時成像的需求，其運算與資料處理量卻是相當龐大的。因此，為了節省成本與降低功率的消耗，在演算法及硬體設計上就必須謹慎地考量，才能在合理的成本下提供即時性的寶貴資訊。
然而目前超音波系統的可攜性仍明顯不足，這在未來將會是愈來愈不可接受的。因為這不但會使病人必須親自到醫院才能作檢查，造成病人的痛苦，且使這樣的醫療資源難以普及化，尤其在一些需要第一線診斷的情況如救護車或戰場等，大型的醫療設備更無法提供立即的救助。
而傳統的都卜勒引擎需要複雜的參數設定，所以沒有辦法在環境變化的情形下適當的自動調節參數即時成像。所以我們希望可以不僅讓受過訓練的專業人員，使其繁複的操作步驟簡化，且降低儀器的操作介面面積以增加可攜性，這些都有利於可攜式系統之使用便利性與有效性。
本論文的研究主題是針對我們正在發展的一套可攜性超音波影像系統，設計並實現智慧型彩色都卜勒的數位訊號處理引擎（Intelligent color Doppler DSP engine）。由於此超音波系統的目標為智慧型、良好的影像品質及高攜帶性，因此本設計也依循著這三個目標前進。首先，本設計根據智慧型（Intelligent）的特色自動根據處理環境調整參數以及智慧地選擇所需的計算複雜度，其具有的彈性能根據使用需求變化動態自動調整系數到最好情況，能方便使用者對各種不同的目標環境都能夠掌握到實用的資訊，並兼顧良好的抗雜訊能力，整體SNR改善6dB以上，且展現了令人滿意的影像品質，另外也同時使得硬體及功率消耗減到最低。本設計以計算統一設備架構(Compute Unified Device Architecture; CUDA)作實現，其能對架構做平行化的處理，並大大加速運算的時間，俾於系統實現在可攜式手持式裝置 (portable handheld device)之上，本論文設計了可應用於可攜性超音波影像系統的高效能都卜勒運算核心。

關鍵字

超音波 ； 彩色都卜勒 ； 濾波器

並列摘要

Ultrasonic imaging is a well-established imaging modality that has the advantages of cost-effectiveness, non-invasiveness, rapid imaging, and portability. color Doppler imaging is a well-established Doppler ultrasound mode and very valuable for visualizing in the real-time distribution of blood flow in a specific region of interest. The blood velocity can be detected by measuring the Doppler frequency shift of the echoes back-scattered from the moving blood. However, it is computationally expensive due to the large computational and data-bandwidth needs in color Doppler imaging. Hence dedicated hardware design is required to reduce the area and power consumption while providing valuable information in real time.
Nevertheless, the portability of current high-frequency ultrasonic imaging systems is insufficient. This will be more and more unacceptable since it is inconvenient and sometimes harmful for patients to go to the hospital for diagnoses. The high cost also reduces the popularity of such medical devices. Moreover, in ambulances or battlefields, portable devices supporting immediate diagnosis can greatly increase the survival rate.
Furthermore, the traditional Doppler engine needs complex parameter settings, it is inconvenient for the user, and it would not work when the users are not familiar with parameter settings for particular environment. Therefore, we simplify complex operations and enhance the efficiency. These features improve the convenience and efficiency of the portable ultrasound systems.
In this thesis, the research topic is to design and implement an intelligent color Doppler DSP engine optimized for the portable ultrasonic imaging system. The major goals of our imaging system are intelligent property, enhanced image quality and portability. Hence, the proposed intelligent color Doppler DSP engine is guided to have three features. First, it is implemented with intelligent consideration, which automatically adjusts parameters and computational complexity according to the operating environment. Second, the proposed DSP engine enables users to acquire sufficient information as needed, its strong de-noising ability results in enhancing image quality.
Third, the proposed Doppler engine is implemented with GPU-based CUDA platform, the parallel processing property significantly accelerates the computation. Finally, the proposed color Doppler DSP engine is very suitable to the clinical and research field.

並列關鍵字

Ultrasound ； Color Doppler ； Filter

參考文獻

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