本文選題：非晶硅平板探測(cè)器 + 電子射野影像裝置　； 參考：《蘇州大學(xué)》2013年碩士論文

【摘要】：非晶硅電子射野影像系統(tǒng)（amorphous silicon electronic portal imaging device，a-Si EPID）在加速器上應(yīng)用非常廣泛，主要是應(yīng)用于圖像引導(dǎo)治療，以糾正擺位誤差，在EPID發(fā)展過程中有不少學(xué)者致力于研究其在質(zhì)控方面的應(yīng)用潛力,如：平坦度和對(duì)稱性分析、光野和射野一致性分析、半影分析、MLC位置驗(yàn)證和劑量驗(yàn)證等。其具有分辨率高、采集數(shù)據(jù)快、即時(shí)顯示二維圖像、抗輻射能力強(qiáng)、使用方便等優(yōu)點(diǎn)，本課題建立在a-Si EPID成像基礎(chǔ)上，研究其劑量驗(yàn)證功能，通過開發(fā)數(shù)據(jù)采集、劑量驗(yàn)證軟件系統(tǒng)DVS(Dosimetric Verification System)，并對(duì)a-SiEPID進(jìn)行一系列的校正，實(shí)現(xiàn)將影像轉(zhuǎn)化為劑量分布。 論文起始介紹了放療劑量驗(yàn)證、常用設(shè)備以及EPID的發(fā)展歷程，而后通過實(shí)驗(yàn)對(duì)a-Si EPID進(jìn)行了初步的劑量學(xué)特性的分析，顯示總體性能較好，但是使用常規(guī)泛野靈敏度校正方法，隨射野離軸距離增大過反應(yīng)效應(yīng)增強(qiáng)。針對(duì)光子與a-SiEPID和水物理反應(yīng)能力的差別，介紹了蒙特卡羅方法，并使用BEAMnrc程序包進(jìn)行了Siemens Primus加速器、a-Si EPID和水模體的模擬、光子筆形束劑量沉積核的計(jì)算，，使用卷積方法將a-Si EPID光子通量轉(zhuǎn)化為水中的通量，然后用模擬泛野的離軸比矩陣進(jìn)行劑量分布校正與灰度-劑量校準(zhǔn)后建立響應(yīng)函數(shù)。在蒙卡模擬過程中同時(shí)分析了射野的相關(guān)特性，如光子和電子的能譜分布、離軸能量、離軸注量、輻射角等難以實(shí)際測(cè)量的物理項(xiàng)，以進(jìn)一步加深對(duì)加速器的了解。 針對(duì)臨床上在劑量驗(yàn)證中常見的Gamma、劑量差(Dose Different, DD)和DTA分析法，設(shè)計(jì)實(shí)驗(yàn)對(duì)三種方法進(jìn)行了優(yōu)劣點(diǎn)的分析，最終在DVS軟件采用Gamma分析法作為劑量驗(yàn)證的算法。隨后使用a-Si EPID和MapCHECK分別采集一頭部腫瘤的治療計(jì)劃，用各自軟件分析，通過對(duì)比結(jié)果顯示a-Si EPID的劑量驗(yàn)證應(yīng)用具備可靠性，但是也呈現(xiàn)出一些問題需進(jìn)一步研究解決。不過隨著問題的解決，這將會(huì)促使a-Si EPID作為新的劑量驗(yàn)證設(shè)備的發(fā)展和應(yīng)用。
[Abstract]:Amorphous silicon electronic portal imaging devicea-Si EPIDs are widely used in accelerators. They are mainly used in image-guided therapy to correct positioning errors. During the development of EPID, many scholars have devoted themselves to studying its application potential in quality control, such as flatness and symmetry analysis, optical field and field consistency analysis, penumbra analysis, position verification and dose verification, etc. It has the advantages of high resolution, fast data acquisition, real-time display of two-dimensional images, strong anti-radiation ability, convenient use and so on. This subject is based on a-Si EPID imaging, studies its dose verification function, and develops data acquisition. The dose verification software system DVS(Dosimetric Verification system, and a series of correction of a-SiEPID are carried out to transform the image into dose distribution. This paper first introduces the radiation dose verification, common equipment and the development history of EPID. Then, the dosimetric characteristics of a-Si EPID are analyzed through experiments. The results show that the overall performance is good, but the conventional pan-field sensitivity correction method is used. The overreaction effect increases with the off-axis distance of the field. In view of the difference between photons, a-SiEPID and hydrophysical reaction ability, Monte Carlo method is introduced, and the simulation of Siemens Primus accelerator, a-Si EPID and water motif, and the calculation of photon pen beam dose deposition nucleus are carried out by using BEAMnrc package. The a-Si EPID photon flux is converted to the flux in water by convolution method, and then the response function is established by using the off-axis ratio matrix of simulated panfield to correct the dose distribution and the gray-dose calibration. In the process of Monka simulation, the related properties of the emission field, such as the energy spectrum distribution of photon and electron, off-axis energy, off-axis beam, radiation angle, and so on, are analyzed simultaneously, so as to further understand the accelerator. In view of the Gamma, Dose difference (DDD) and DTA analysis, which are commonly used in clinical dose verification, the advantages and disadvantages of the three methods are analyzed in the design experiment. Finally, the Gamma analysis method is used as the dose verification algorithm in the DVS software. Then a-Si EPID and MapCHECK were used to collect the treatment plan of a head tumor. The results of comparison showed that the dose verification of a-Si EPID was reliable, but some problems needed to be solved. However, as the problem resolves, this will lead to the development and application of a-Si EPID as a new dose verification device.
【學(xué)位授予單位】：蘇州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：R144.1;TN36

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 孫彥澤;苗利;殷旭君;談?dòng)押?文萬信;;非晶硅電子射野影像裝置的性能研究[J];輻射研究與輻射工藝學(xué)報(bào);2012年03期

本文編號(hào)：1900922