本文選題：蒙特卡羅 + 三源CT�。� 參考：《上海交通大學》2012年碩士論文

【摘要】：計算機斷層成像技術(shù)（CT）是一種重要的醫(yī)學成像技術(shù)，從誕生到現(xiàn)在的數(shù)十年的時間里經(jīng)歷了幾代進步，仍在不斷地發(fā)展和變革。自從2005年西門子公司率先推出了雙源CT后，，多源CT的概念逐漸被人接受和認可。作為雙源CT的延伸，三源CT將帶來更快的數(shù)據(jù)采集速度和更高質(zhì)量的重建圖像，其精確重建算法也早已得到證明。作為評判CT設備性能的重要指標，散射和劑量是在CT研發(fā)中不可不考慮和研究的問題。散射帶來的問題是使重建圖像的值發(fā)生偏移，產(chǎn)生偽影或降低圖像對比度，這些都會給醫(yī)學診斷帶來困難。而劑量則是涉及到輻射安全的問題。日益增加的醫(yī)療檢測輻射問題使得放射安全和防護的重要性顯得更加突出，設備給受檢者帶來的輻射劑量水平是每一臺CT研制中都要考慮的。因此本論文就這兩個問題，通過基于蒙特卡羅法的仿真技術(shù)，構(gòu)建出虛擬的三源錐束X線CT系統(tǒng)，分析和研究了三源CT的散射和劑量情況。本文的主要內(nèi)容包括： 在開源蒙特卡羅仿真工具EGSnrc的基礎(chǔ)上開發(fā)了CT仿真系統(tǒng)SimProj。該軟件可根據(jù)需要定制系統(tǒng)結(jié)構(gòu)、掃描的方式、軌跡、物理參數(shù)等，具備很強的擴展性和復用性；通過對三源錐束CT的仿真，我們分析了在不同錐角下散射光強的變化，比較了由各個光源引起的散射光及其引起的圖像質(zhì)量問題，對重建值偏移、圖像對比度等問題做了量化的分析；對三源CT掃描數(shù)字人體模型的輻射劑量分析發(fā)現(xiàn)，盡管增加了兩套影像系統(tǒng)同時工作，但是由于掃描方式的改變，三源CT和單源CT在掃描等距離范圍時，對人體產(chǎn)生的輻射劑量是等量的。這些研究成果為三源CT的實際研發(fā)提供了幫助，同時也是為今后的仿真研究奠定了基礎(chǔ)。
[Abstract]:Computed Tomography (CT) is an important medical imaging technology, which has undergone several generations of progress from its birth to now, and is still developing and reforming. Since Siemens introduced dual source CT in 2005, the concept of multi-source CT has been accepted and accepted. As an extension of dual-source CT, three-source CT will bring faster data acquisition speed and higher quality reconstruction image, and its accurate reconstruction algorithm has been proved. As an important index to evaluate the performance of CT equipment, scattering and dose are important problems in CT research and development. The problem of scattering is to offset the reconstructed image, produce artifacts or reduce the contrast of the image, which will bring difficulties to medical diagnosis. The dose is related to the problem of radiation safety. The increasing medical detection radiation problem makes the importance of radiation safety and protection more prominent. The radiation dose level brought by the equipment to the examinees is considered in every CT development. Therefore, in this paper, a virtual three-source cone-beam X-ray CT system is constructed based on Monte Carlo simulation technology, and the scattering and dose of three-source CT are analyzed and studied. The main contents of this paper are as follows: a CT simulation system SimProj. based on the open source Monte Carlo simulation tool EGSnrc is developed. The software can customize the system structure, scanning mode, trajectory, physical parameters and so on according to the need, and has strong expansibility and reusability. Through the simulation of three-source cone beam CT, we analyze the variation of scattering light intensity at different cone angles. The scattering light caused by each light source and the image quality problems caused by each light source are compared, the reconstruction value offset and image contrast are analyzed quantitatively, and the radiation dose analysis of three source CT scanning digital human body model is found. Although two sets of imaging systems are added to work simultaneously, due to the change of scanning mode, the radiation dose produced by three-source CT and single-source CT is equal to that of human body in the same range of scanning distance. These results are helpful for the practical research and development of three source CT, and also lay a foundation for future simulation research.
【學位授予單位】：上海交通大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：R142

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本文編號：1993900