新時代非侵入性檢測儀器OpenWater

如果我們能夠用數位方式捕獲散射光線，並且重新建構組織原始形貌，就可以做出許多有趣的事情。最讓人振奮的應用應屬這篇無誤( OpenWater  Mary lou Jepsen )。

微型模組

約莫半年前，得知這個系統的存在，就開始筆記，概念上，它應用近紅外光可穿透人體特性，為身體組織內打光。但是當組織內的光散射成一大片時，是無法分析的。也因此推測，因為越深入身體組織，光線散射程度越高，可蒐集資訊越少，所以他們的展示品做成環繞身體的束帶形狀，每個部位僅蒐集附近區域訊息。

第二步驟，利用超音波會改變光的特性，經由控制在身體內不同位置聚焦，原本身體內瀰漫的紅色散射光，在聚焦點上，會有相位變化(影片中提到變成黃色散射光，似乎不可能吧)。本系統與超音波息息相關(連結)，這種發射聚焦的特性，在OpenWater系統中扮演很大作用，能為組織中某個特定區域，提供高能量，影像光波長改變。

第三步是，排除所有紅色光，僅分析黃光(同上述，非常質疑理論可行，文中稱為wavelength shifter)，重建該區域立體資訊。重複第二步動作，同時調整對焦位置，進行C-Scan，如此重複進行，就能得到整個區域的立體資訊。對於捕捉散射光，似乎可以再參考下面內容。

例如Monte Carlo光路模擬，下圖是25個紅外630 nm光子在食道組織的散射模擬，部分由表面逃逸，也有許多進入深層被吞噬。GITHUB上有完整範例程式(連結)。

連結

同時也有人試著利用這個特性，嘗試由散射結果，反向重建原本組織結構，如下圖，類似概念應該也就上述的原理(Monte Carlo模拟肠道组织的非接触式漫反射光谱)。

連結 連結

回到Openwater簡報內容。

連結

下面是2018年某個演講摘錄畫面(連結)，已經可以分析和重建躲藏在盒子中的組織，且精度為0.5mm。雖然始終沒找到相關技術文件，還不能確定可行性，但僅僅"感到"科學技術的進步，就讓人振奮不已。網路上中文且探討這項技術文件不多，可參考交大黃俊榮(老婆臉友)文章(連結)。

最近陸續看到PATENT資料，認真參考，連結1 連結2 連結3  PATENTS的列表(連結) 挑了一篇看(連結)，有些觀念要澄清，例如是打出全息圖案，接收的原理應該是聲光衍射(連結)，無透鏡系統(連結)。

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因著2024他們開放更多資料，初步看了一下，上述技術被公司稱為Holographic Acousto-optic Imaging，是四個項目之一(其餘為lensless搭配雷射，超音波治療，機器校正)，詳細內容如連結。扣除校正這種輔助項目，此種Holographic Acousto-optic Imaging全像功能的開發似乎停擺了。連結

The Openwater Holographic Acousto-optic Imaging setup is a novel imaging modality employing both optical and ultrasound modalities to provide the functional information of near-infrared spectroscopy and spatial sensitivity of ultrasound. These devices have been used in a variety of pre-clinical studies.

Holographic acousto-optic imaging works by first directing light from a laser beam into tissue. When this light travels inside the tissue, it will be rapidly diffusely scattered and ultimately make it challenging to obtain any structural information from it. However, when an ultrasound beam’s focus is placed within the tissue at the same time, the laser light that crosses that focus region will be shifted to a very slightly different wavelength, this essentially ‘tags’ the light. By using lasers with very specific properties (notably high coherence), one can sort out this ‘tagged’ light from all of the other light exiting the tissue by holographically recombining it with some of the original laser light, similarly shifted in wavelength. Thus, holographic acousto-optic imaging can provide useful functional information at great spatial detail. This has been diagrammed in the image below. By moving the ultrasound focus across the entire tissue area, one can generate a 3D image of the functional properties of the tissue. Greater detail on the Openwater holographic acousto-optic image setup can be found in the hardware and software repositories on GitHub.

從資料看，他們重點放在後續兩項。2024/2/16資料：公司專注於雷射和lensless結合。Blood Flow OPEN MOTION 3.0(連結)，屬於非侵入性偵測裝置，如圖。

呈現結果是連續性的數值而非三維空間影像。雖然不是醫學專家，但基於腦部血流並沒有絕對值，單一數字能代表什麼呢？

The technology of Openwater Blood Flow devices is a novel method that utilizes light to measure and quantify blood flow within tissue. The technology utilizes highly refined laser light, emitting an extremely narrow range of wavelengths for very brief periods of time. As this specific type of light passes through tissue, its properties can be altered by the flow or movement of blood. Once the light exits the tissue, detecting and quantifying the small changes in flow is achieved by illuminating the transmitted light onto sensors with numerous tiny yet highly sensitive pixels. To accomplish this all, the technique employs simple, yet very sophisticated lasers and sensors that are either already in production for, or under development for, the mass market consumer electronics supply chain. This ultimately allows the device to be scaled down in cost dramatically compared to any other medical device, while providing unique and important biological information. Additional details on this technology and its application to stroke diagnosis can be found below:

2024/2/16資料：公司專注於超音波治療。使用機器OPEN-LIFU(連結)。看描述就是個可定位的超音波轟擊器，對象是腦部。值得注意是過程中需要外部機器例如MRI和CT輔助取得三維空間的資料庫，才能對比進行轟擊(這和腎結石碎石有什麼不同嗎？)。

因為是侵入性治療，過FDA的程序繁雜。功能包括了兩個，Neuromodulation和Oncolysis。The Open-TFUS Neuromodulation Platform is an ultrasound system that transmits focused ultrasound beams into a subject’s brain with the intention to be able to treat a variety of neurological diseases. The device works by uniquely employing a small array of low-frequency ultrasound transducers in order to precisely steer a small amount of energy to target regions within the brain. This platform has been used in a human clinical trial for depression.

The Openwater Preclinical Oncolysis Prototype is a therapeutic ultrasound system that uses low-frequency ultrasound with specific acoustic parameters in order to specifically target cancer cells while sparing surrounding healthy tissue. This platform has been used in a preclinical small animal study, demonstrating its performance.