本文關(guān)鍵詞： 微型CT 快速掃描 呼吸門控 活體小動(dòng)物　出處：《華中科技大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：微型CT具有高空間分辨率，能夠無(wú)損地獲得小動(dòng)物的結(jié)構(gòu)信息等優(yōu)點(diǎn)，為各種疾病模型的研究、新藥研發(fā)等提供了長(zhǎng)時(shí)間連續(xù)監(jiān)測(cè)的工具，已經(jīng)在生物醫(yī)學(xué)研究中發(fā)揮重要作用。然而，使用微型CT對(duì)活體小動(dòng)物胸部或腹部等成像時(shí)，呼吸活動(dòng)會(huì)產(chǎn)生運(yùn)動(dòng)偽影，導(dǎo)致圖像空間分辨率的降低。為了消除這些影響，出現(xiàn)了微型CT呼吸門控技術(shù)。 為了在微型CT系統(tǒng)上實(shí)現(xiàn)呼吸門控技術(shù)，本文在實(shí)驗(yàn)室已有的微型CT系統(tǒng)上通過(guò)平板探測(cè)器圖像采集傳輸?shù)臅r(shí)序信號(hào)與旋轉(zhuǎn)臺(tái)旋轉(zhuǎn)之間的同步實(shí)現(xiàn)了快速掃描，縮短了系統(tǒng)的掃描時(shí)間，可實(shí)現(xiàn)最大30fps的圖像采集速度�；谠摽焖�、高空間分辨率的微型CT系統(tǒng)，發(fā)展了基于硬件和軟件的兩種活體小動(dòng)物回顧性呼吸門控技術(shù)�；谟布姆椒ㄊ峭ㄟ^(guò)固定在麻醉的小動(dòng)物腹部的空氣壓力傳感器來(lái)獲取呼吸信號(hào)，而基于軟件的方法是利用掃描得到的投影圖像的特征來(lái)獲取呼吸信號(hào)。得到呼吸信號(hào)后，根據(jù)每幅投影圖像與呼吸信號(hào)之間的對(duì)應(yīng)關(guān)系，按照呼吸信號(hào)的幅度，將投影圖像歸類于不同的呼吸相位，最后使用FDK算法對(duì)處于同一呼吸相位的投影圖像進(jìn)行數(shù)據(jù)重建。 結(jié)果表明，呼吸門控的CT圖像的質(zhì)量?jī)?yōu)于非呼吸門控的CT圖像，經(jīng)呼吸門控的CT圖像可以觀察到更清楚的肺隔膜邊界及肋骨結(jié)構(gòu)，表明呼吸門控技術(shù)能夠很好的消除運(yùn)動(dòng)偽影。通過(guò)比較兩種呼吸門控方法，發(fā)現(xiàn)這兩種方法在提高CT圖像質(zhì)量上具有一致性。但是基于軟件的方法只有在圖像采集幀速到達(dá)15fps時(shí)才能有效地獲得呼吸信號(hào)，而基于硬件的方法雖然增加了系統(tǒng)的復(fù)雜程度，但是能穩(wěn)定地獲取呼吸信號(hào)，，具有更為廣泛的應(yīng)用范圍。
[Abstract]:Micro CT has the advantages of high spatial resolution and the ability to obtain structural information of small animals without damage. It provides a long-term continuous monitoring tool for the study of various disease models and the development of new drugs. It has played an important role in biomedical research. However, breathing activities can produce motion artifacts when microCT is used to visualize the chest or abdomen of small living animals. In order to eliminate these effects, micro CT respiratory gating technology has been developed in order to reduce the spatial resolution of images. In order to realize the respiratory gating technology on the micro CT system. In this paper, the scanning time is shortened and the scanning time is shortened by the synchronization between the time sequence signal collected and transmitted by the flat panel detector image and the rotation of the rotating table on the existing miniature CT system in the laboratory. The maximum image acquisition speed of 30 fps can be achieved. Based on the fast and high spatial resolution micro CT system. Two retrospective breathing gating techniques based on hardware and software for small animals in vivo are developed. The hardware based approach is to obtain respiratory signals by means of air pressure sensors fixed in the abdomen of anesthetized small animals. The method based on software is to obtain the respiratory signal by using the features of the scanned projection image. After obtaining the respiratory signal, according to the corresponding relationship between each projection image and the respiratory signal, according to the amplitude of the respiratory signal. The projection images are classified into different breathing phases, and the FDK algorithm is used to reconstruct the projected images with the same breathing phase. The results showed that the quality of respiratory gated CT images was better than that of non-respiratory gated CT images, and the pulmonary septum boundary and rib structure could be observed more clearly by respiratory gated CT images. The results show that the breathing gating technique can eliminate motion artifacts very well. It is found that the two methods are consistent in improving the quality of CT images, but the software-based method can only obtain respiratory signals effectively when the frame rate of image acquisition reaches 15fps. Although the hardware-based method increases the complexity of the system, it can obtain respiratory signals stably and has a wider range of applications.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：R814.42

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