三維生物發(fā)光斷層成像系統(tǒng)搭建與算法研究
發(fā)布時間：2018-12-18 14:12
【摘要】：生物發(fā)光斷層成像作為光學(xué)分子影像學(xué)的重要分支,能夠從細(xì)胞和分子水平對生物體內(nèi)腫瘤的生長和轉(zhuǎn)移,特定基因的表達(dá)等諸多生物學(xué)過程進(jìn)行分析和檢測,可廣泛應(yīng)用于腫瘤檢測、基因治療及藥物研發(fā)等領(lǐng)域。目前,生物發(fā)光斷層成像系統(tǒng)成熟產(chǎn)品不多,美國精諾真IVIS系列產(chǎn)品在市場上占主要份額,但價格昂貴。因此,研究具有自主知識產(chǎn)權(quán),高性能指標(biāo)的生物發(fā)光斷層成像系統(tǒng)勢在必行。本文研究了生物發(fā)光斷層成像的重建算法,并設(shè)計(jì)和搭建了成像儀硬件系統(tǒng)。主要工作如下:1、研究了生物發(fā)光斷層成像中光在組織內(nèi)的傳輸模型。針對輻射傳輸方程的復(fù)雜性,將光在生物組織內(nèi)的傳輸簡化為擴(kuò)散近似方程,并用有限元方法求解方程的系數(shù)矩陣。2、將光在空氣與透鏡系統(tǒng)中的傳輸簡化為小孔模型,利用CCD成像原理推導(dǎo)出圖像灰度值與光輻射功率的線性關(guān)系,并根據(jù)朗伯余弦定律推導(dǎo)出像點(diǎn)與物點(diǎn)間的能量關(guān)系,避免傳統(tǒng)積分球校準(zhǔn)方法的高成本及復(fù)雜性。通過CCD采集發(fā)光圖像,實(shí)現(xiàn)了成像物體體表光輻照度的重建。仿體和豬肉組織實(shí)驗(yàn)驗(yàn)證了本文提出方法的有效性。3、研究了生物發(fā)光斷層成像體內(nèi)光源重建算法。本文提出了自適應(yīng)選取可行區(qū)的策略以降低重建算法的欠定性和病態(tài)性。該方法不但可以有效避免傳統(tǒng)手動選取可行區(qū)帶來的系統(tǒng)不穩(wěn)定性,還可以提高體內(nèi)光源的重建精度。可行區(qū)劃定后,針對目前系數(shù)矩陣抽取方法會破壞矩陣正定性的問題,本文提出了模型降階算法,可確保矩陣的正定性。最后,結(jié)合Tihonov正則化和共軛向量基算法快速準(zhǔn)確實(shí)現(xiàn)了體內(nèi)光源的重建。4、設(shè)計(jì)和搭建了生物發(fā)光斷層成像儀的軟硬件系統(tǒng)。通過設(shè)計(jì)的旋轉(zhuǎn)平臺采集八視角的發(fā)光圖像以增加先驗(yàn)信息,可有效降低系統(tǒng)的欠定性。利用仿體和小鼠實(shí)驗(yàn)對成像系統(tǒng)綜合性能指標(biāo)進(jìn)行驗(yàn)證,仿體實(shí)驗(yàn)光源重建的定位精度在1mm以內(nèi),小鼠實(shí)驗(yàn)光源重建的定位精度在2mm以內(nèi)。上述研究表明,論文研究的內(nèi)容可有效降低生物發(fā)光斷層成像系統(tǒng)的欠定性及病態(tài)性問題,提高體內(nèi)光源重建的定位精度。
[Abstract]:As an important branch of optical molecular imaging, bioluminescence tomography can analyze and detect many biological processes, such as tumor growth and metastasis, specific gene expression and so on. Can be widely used in tumor detection, gene therapy and drug development and other fields. At present, the bioluminescence tomography system mature products are not many, the United States Jinnuzhen IVIS series products in the market share, but the price is expensive. Therefore, it is imperative to study bioluminescence tomography system with independent intellectual property and high performance index. In this paper, the reconstruction algorithm of bioluminescence tomography is studied, and the hardware system of the imaging instrument is designed and built. The main work is as follows: 1. The light transmission model in bioluminescence tomography is studied. In view of the complexity of the radiation transfer equation, the propagation of light in biological tissues is simplified as a diffusion approximation equation, and the coefficient matrix of the equation is solved by using the finite element method. 2. The transmission of light in the air and lens system is simplified as a small hole model. The linear relationship between image gray value and optical radiation power is derived by using CCD imaging principle, and the energy relationship between image point and object point is deduced according to Lambert's cosine law, which avoids the high cost and complexity of traditional integrated sphere calibration method. The light irradiance of the body surface of the imaging object is reconstructed by collecting the luminous image by CCD. Experiments of simulated body and pork tissue verify the effectiveness of the proposed method. 3. The reconstruction algorithm of bioluminescence tomography in vivo is studied. In this paper, a strategy of adaptive selection of feasible region is proposed to reduce the ill-nature and ill-condition of the reconstruction algorithm. This method can not only effectively avoid the instability caused by the traditional manual selection of feasible areas, but also improve the reconstruction accuracy of the internal light source. In view of the problem that the method of coefficient matrix extraction can destroy the positive definiteness of matrix after the feasible area is delineated, a model reduction algorithm is proposed to ensure the positive definiteness of matrix. Finally, combining with Tihonov regularization and conjugate vector basis algorithm, the reconstruction of internal light source is realized quickly and accurately. 4. The hardware and software system of bioluminescence tomography is designed and built. In order to increase the priori information the luminous images of eight angles of view are collected by the designed rotating platform which can effectively reduce the undercharacterization of the system. The synthetic performance indexes of the imaging system were verified by imitating body and mouse experiments. The localization accuracy of the reconstruction was within 1mm and the localization accuracy of mouse experimental light source was within 2mm. The above results show that the content of this paper can effectively reduce the problem of ill-quality and ill-condition of bioluminescence tomography system and improve the positioning accuracy of the reconstruction of the light source in vivo.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TP391.41
，
本文編號：2385964
[Abstract]:As an important branch of optical molecular imaging, bioluminescence tomography can analyze and detect many biological processes, such as tumor growth and metastasis, specific gene expression and so on. Can be widely used in tumor detection, gene therapy and drug development and other fields. At present, the bioluminescence tomography system mature products are not many, the United States Jinnuzhen IVIS series products in the market share, but the price is expensive. Therefore, it is imperative to study bioluminescence tomography system with independent intellectual property and high performance index. In this paper, the reconstruction algorithm of bioluminescence tomography is studied, and the hardware system of the imaging instrument is designed and built. The main work is as follows: 1. The light transmission model in bioluminescence tomography is studied. In view of the complexity of the radiation transfer equation, the propagation of light in biological tissues is simplified as a diffusion approximation equation, and the coefficient matrix of the equation is solved by using the finite element method. 2. The transmission of light in the air and lens system is simplified as a small hole model. The linear relationship between image gray value and optical radiation power is derived by using CCD imaging principle, and the energy relationship between image point and object point is deduced according to Lambert's cosine law, which avoids the high cost and complexity of traditional integrated sphere calibration method. The light irradiance of the body surface of the imaging object is reconstructed by collecting the luminous image by CCD. Experiments of simulated body and pork tissue verify the effectiveness of the proposed method. 3. The reconstruction algorithm of bioluminescence tomography in vivo is studied. In this paper, a strategy of adaptive selection of feasible region is proposed to reduce the ill-nature and ill-condition of the reconstruction algorithm. This method can not only effectively avoid the instability caused by the traditional manual selection of feasible areas, but also improve the reconstruction accuracy of the internal light source. In view of the problem that the method of coefficient matrix extraction can destroy the positive definiteness of matrix after the feasible area is delineated, a model reduction algorithm is proposed to ensure the positive definiteness of matrix. Finally, combining with Tihonov regularization and conjugate vector basis algorithm, the reconstruction of internal light source is realized quickly and accurately. 4. The hardware and software system of bioluminescence tomography is designed and built. In order to increase the priori information the luminous images of eight angles of view are collected by the designed rotating platform which can effectively reduce the undercharacterization of the system. The synthetic performance indexes of the imaging system were verified by imitating body and mouse experiments. The localization accuracy of the reconstruction was within 1mm and the localization accuracy of mouse experimental light source was within 2mm. The above results show that the content of this paper can effectively reduce the problem of ill-quality and ill-condition of bioluminescence tomography system and improve the positioning accuracy of the reconstruction of the light source in vivo.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TP391.41
，
本文編號：2385964
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