本文選題：X射線 + 光(?)相位襯度成像�。� 參考：《中國科學技術(shù)大學》2017年碩士論文

【摘要】：X射線應(yīng)用廣泛,在臨床醫(yī)學、材料科學及國土安全等領(lǐng)域占有重要地位。為了實現(xiàn)對輕元素組成物質(zhì)的檢測,X射線相位襯度成像應(yīng)運而生,近二十年來得到了迅速的發(fā)展,相繼開展了多種X射線相位襯度成像技術(shù)的研究。X射線光柵相位襯度成像技術(shù)的出現(xiàn),不再對光源有嚴格要求,能在常規(guī)X光源上實現(xiàn)折射信息的提取,有臨床應(yīng)用的可能,因此獲得了廣泛的關(guān)注,關(guān)于該技術(shù)的研究迅速展開。針對X射線光柵相襯成像技術(shù),本論文主要在光柵相位襯度成像實驗平臺的搭建、光柵的研制及相位襯度成像方法的研究方面開展了以下工作:1.X射線光柵相位襯度成像實驗平臺的搭建和圖像采集系統(tǒng)的優(yōu)化搭建X射線光柵相位襯度成像實驗平臺,該成像裝置將傳統(tǒng)的Talbot-Lau干涉儀和幾何投影成像原理結(jié)合在一起。主要有以下幾個優(yōu)點:光柵制作容易,有利于實現(xiàn)高劑量的相位襯度成像;成像裝置設(shè)計更緊湊,對成像系統(tǒng)的機械穩(wěn)定性要求低;成像能量選擇更多,應(yīng)用范圍更廣。通過Labview編程,將實驗時所需要的操作整合到一個界面上,我們可以同時實現(xiàn)對X射線光源參數(shù)的設(shè)置,對光柵位移運動的操作,圖像采集和圖像后處理,方便實驗人員操作,減少了實驗時間。在圖像采集方面,我們介紹了一種名為積分水桶法的圖像采集方法,對比傳統(tǒng)的相位步進法,它的主要優(yōu)點有:分析光柵連續(xù)移動,這種連續(xù)運動的方式有利于成像系統(tǒng)的機械的穩(wěn)定性;X射線探測器連續(xù)采集圖像,減少了樣品接受到的不必要的輻射。2.X射線光柵相位襯度成像重要部件光柵的制作作為X射線光柵相位襯度成像的重要部件,光柵的質(zhì)量對成像結(jié)果有決定性的作用。在制作大高寬比光柵的過程中,經(jīng)常會出現(xiàn)光柵結(jié)構(gòu)失效的問題。針對這個問題,我們在光柵制作工藝上提出改進方案,可以逐步制作出滿足成像要求的大高寬比光柵。3.X射線光柵相位襯度成像背景校正方法的研究通過對目前常用的兩種背景校正方法的對比研究,發(fā)現(xiàn)在背景圖像存在較大的不均勻性時,其中一種方法會出現(xiàn)錯誤。針對這個問題,我們在該方法的基礎(chǔ)上提出了優(yōu)化方案,在相位步進過程中采用循環(huán)移位尋找正確的起始位置,對原有的方法進行了優(yōu)化。最后,模擬分析和實驗數(shù)據(jù)證實該方法可行且正確。
[Abstract]:X-ray is widely used and plays an important role in clinical medicine, material science and homeland security.In order to realize the detection of light element composition matter, X-ray phase contrast imaging emerged as the times require, and it has been developed rapidly in the past twenty years.Many kinds of X-ray phase contrast imaging techniques have been carried out one after another. The appearance of X-ray grating phase contrast imaging technology is no longer strictly required to the light source, and it can be used to extract refraction information on the conventional X light source, which has the possibility of clinical application.Therefore, wide attention has been paid to the research of this technology.Aiming at the phase contrast imaging technology of X-ray grating, this paper mainly builds the experimental platform of grating phase contrast imaging.The development of grating and the research of phase contrast imaging method have carried out the following work: 1. Build the experimental platform of X-ray grating phase contrast imaging and optimize the image acquisition system to build the experimental platform of X-ray grating phase contrast imaging.The imaging device combines the traditional Talbot-Lau interferometer with the geometric projection imaging principle.The main advantages are as follows: the grating is easy to fabricate, which is conducive to the realization of high dose phase contrast imaging; the imaging device is designed more compact and requires low mechanical stability of the imaging system; the imaging energy is more selective, and the range of application is wider.Through Labview programming, the operation needed in experiment can be integrated into a single interface. We can set the parameters of X-ray light source at the same time, operate the movement of grating displacement, capture images and post-process images, and facilitate the operation of the experimenter.The experiment time is reduced.In the aspect of image acquisition, we introduce an image acquisition method called integral bucket method. Compared with the traditional phase step method, its main advantages are: analyzing the continuous movement of grating,This mode of continuous motion is conducive to the mechanical stability of the imaging system and the continuous acquisition of images by X-ray detectors.The unnecessary radiation received by the sample is reduced. 2. The fabrication of the grating as an important part of the X-ray grating phase contrast imaging is an important part of the X-ray grating phase contrast imaging. The quality of the grating plays a decisive role in the imaging results.In the process of fabricating large aspect ratio gratings, the structural failure of gratings often occurs.In order to solve this problem, we put forward the improvement scheme in grating fabrication technology.The background Correction method of Phase contrast Imaging with large aspect ratio grating .3.The background Correction method of Phase contrast Imaging based on X-ray grating can be made step by step. The comparison of two kinds of background correction methods commonly used at present can be carried out.It is found that there are errors in one of the methods when there is a large heterogeneity in the background image.In order to solve this problem, we put forward an optimization scheme based on this method. In the process of phase step, we use cyclic shift to find the correct starting position, and optimize the original method.Finally, the simulation analysis and experimental data show that the method is feasible and correct.
【學位授予單位】：中國科學技術(shù)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O434.1;TP391.41

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本文編號：1752086