本文選題：電子射野影像系統(tǒng) + 加速器日志文件��； 參考：《中國疾病預(yù)防控制中心》2017年碩士論文

【摘要】：電子射野影像系統(tǒng)(EPID)最初主要用于位置驗(yàn)證,但是它實(shí)際上是一組輻射探測器,經(jīng)過適當(dāng)?shù)目潭群托?zhǔn)可以用于放射治療劑量學(xué)測量。許多研究表明,EPID在治療前和在體劑量測量中都具有明顯的優(yōu)勢。在體劑量測量是通過在計(jì)劃實(shí)施過程中實(shí)時(shí)獲取透射影像來重建體內(nèi)劑量,從而實(shí)現(xiàn)患者體內(nèi)計(jì)算和照射劑量分布的比較。加速器日志文件(Dynalog files)記錄了計(jì)劃執(zhí)行過程中設(shè)備的運(yùn)行參數(shù),通過調(diào)用“Dynalogfiles”信息在CT圖像上重建劑量分布,可以輔助實(shí)驗(yàn)測量方法進(jìn)行劑量學(xué)質(zhì)量控制。本文針對(duì)基于EPID的劑量學(xué)質(zhì)量控制進(jìn)行了深入的研究。首先,研究了基于EPID的治療前劑量驗(yàn)證系統(tǒng)EPIbeam和基于治療計(jì)劃系統(tǒng)(TPS)計(jì)劃治療參數(shù)的Mobius 3D系統(tǒng)的建模、算法及劑量計(jì)算過程;其次,結(jié)合這兩套治療前劑量驗(yàn)證系統(tǒng)對(duì)28例盆腔病例容積調(diào)強(qiáng)放射治療(VMAT)計(jì)劃進(jìn)行了劑量驗(yàn)證研究;然后,深入地研究了基于EPID重建體內(nèi)劑量的驗(yàn)證系統(tǒng)EPIgray和基于“Dynalogfiles”的MobiusFX系統(tǒng)的建模、算法及劑量計(jì)算;最后,選取30例VMAT(15例盆腔病例和15例頭頸部病例)計(jì)劃進(jìn)行了體內(nèi)劑量學(xué)驗(yàn)證,分別利用電離室測量等中心處劑量值、基于EPID影像結(jié)合EPIgray重建等中心點(diǎn)劑量值和“Dynalog files”結(jié)合MobiusFX重建等中心點(diǎn)的劑量,將兩組重建值與電離室測量值進(jìn)行比較分析。EPIbeam系統(tǒng)是將實(shí)際上的EPID影像和TPS計(jì)算的射野影像同時(shí)經(jīng)過相應(yīng)劑量模型轉(zhuǎn)換成水下5 cm處的平面劑量分布,進(jìn)而將兩者進(jìn)行對(duì)比;Mobius 3D系統(tǒng)是將TPS的原始計(jì)劃治療參數(shù)經(jīng)過倒錐卷積/疊加算法(CCC/S)重新計(jì)算劑量分布;治療前劑量驗(yàn)證中,基于EPID結(jié)合軟件EPIbeam的方法得到的是二維平面劑量分布的結(jié)果,其γ通過率均大于95%,Mobius 3D計(jì)算的是三維體素內(nèi)的劑量分布,有兩例γ通過率低于95%,但是均高于90%,大部分計(jì)劃γ通過率高于95%,均符合臨床劑量學(xué)要求;EPIgray借助于“fTMR”算法利用治療過程中EPID獲取的射野影像重建出模體內(nèi)感興趣點(diǎn)的劑量;Mobius FX是在“Dynalog files”反饋的計(jì)劃執(zhí)行時(shí)設(shè)備的運(yùn)行參數(shù)的基礎(chǔ)上利用CCC/S算法重建劑量;在體劑量驗(yàn)證中,盆腔計(jì)劃和頭頸部計(jì)劃電離室測量值以及基于EPID和“Dynalog files”的重建平均值分別為(2.34±0.28)Gy、(2.31±0.26)Gy、(2.35±0.29)Gy和(1.58±0.12)Gy、(1.56±0.12)Gy 和(1.59±0.10)Gy。兩個(gè)部位基于 EPID的重建值與電離室測量值相對(duì)偏差以及“Dynalog files”的重建值與電離室測量值相對(duì)偏差的平均值分別為(-1.11±2.42)%、(0.82±1.73)%和(-1.27±2.48)%、(0.56±1.91)%,符合臨床劑量學(xué)要求。兩組重建值與電離室測量值分別進(jìn)行配對(duì)t檢驗(yàn),結(jié)果顯示兩組重建值與電離室測量值之間相比較差異均無統(tǒng)計(jì)學(xué)意義(t=1.91、-1.83,P0.05;t=2.01、-0.88,P0.05)。綜上所述,正確合理的利用EPID對(duì)先進(jìn)放療技術(shù)進(jìn)行劑量學(xué)質(zhì)量控制的方法不影響治療、便于推廣,不僅可以提高治療前劑量驗(yàn)證的效率,而且在實(shí)時(shí)監(jiān)測患者接受放療劑量方面具有很大的優(yōu)勢,有利于開展對(duì)患者劑量核查工作�；谕暾�、準(zhǔn)確的“Dynalog files”重建劑量的方法操作簡單,可以同測量方法相輔相成,為形成一種快速、簡單的先進(jìn)放療技術(shù)劑量監(jiān)測方法提供參考。
[Abstract]:Electronic field imaging system (EPID) is primarily used for location verification, but it is actually a set of radiation detectors. After appropriate calibration and calibration, it can be used for radiation therapy dosimetry. Many studies have shown that EPID has obvious advantages in both before and in volume measurement. In the process of application, the transmission image is obtained in real time to reconstruct the dose of the body, thus the comparison of the dose distribution in the patient's body is realized. The accelerator log file (Dynalog files) records the operating parameters of the equipment during the execution of the plan. The dose distribution can be reconstructed by calling the "Dynalogfiles" information on the CT image, which can assist the experimental test. Quantitative method is used to control dosimetry quality control. In this paper, the quality control of dosimetry based on EPID is studied deeply. First, the modeling, algorithm and dose calculation process of the pre treatment dose verification system based on EPID EPIbeam and the Mobius 3D system based on the treatment planning system (TPS) plan treatment parameters are studied. Secondly, the two sets are combined. The pre treatment dose verification system conducted a dose verification study on 28 cases of pelvic case volume intensity modulated radiation therapy (VMAT). Then, we studied the modeling, calculation and dose calculation of the system EPIgray and the MobiusFX system based on "Dynalogfiles" based on the EPID reconstruction. Finally, 30 cases of pelvic disease (15 cases of pelvic disease) were selected. In the case of 15 cases and 15 cases of head and neck, the dose value of the center point at the ionization chamber measurement, based on the dose values of the central point of the EPID image combined with EPIgray reconstruction and the dose of "Dynalog files" combined with the MobiusFX reconstruction, are used to compare the values of the two rebuilt values to the ionization chamber measurements to compare and analyze.EPIbeam The system is to convert the actual EPID images and TPS images into the plane dose distribution at 5 cm under the corresponding dose model at the same time, and then compare them. The Mobius 3D system is to re calculate the dose distribution through the inverted convolution convolution / superposition algorithm (CCC /S) of the TPS's original planned treatment parameters, and to verify the dose before treatment. In this method, the method based on EPID combined with software EPIbeam is the result of two-dimensional plane dose distribution, its gamma passing rate is greater than 95%, Mobius 3D is calculated in the dose distribution of three-dimensional voxel, two cases of gamma passing rate are lower than 95%, but all are higher than 90%, most of the planned gamma pass rate is higher than 95%, all in line with the clinical dosimetric requirements; EPIgray with the aid of The "fTMR" algorithm uses the field images obtained by the EPID in the treatment process to reconstruct the dose of the point of interest in the body; Mobius FX is based on the operating parameters of the "Dynalog files" feedback device, using the CCC/S algorithm to reconstruct the dose. In the body dose verification, the pelvic cavity plan and the head and neck ionization chamber are measured and the measured values are also measured. The reconstruction averages based on EPID and "Dynalog files" are (2.34 + 0.28) Gy, (2.31 + 0.26) Gy, (2.35 + 0.29) Gy and (1.58 + 0.12) Gy, (1.56 + 0.12) Gy and (1.59 + 0.10) Gy. two parts based on the relative deviation of the reconstructed values of EPID from the measured values of the ionization chamber and the relative deviation between the reconstructed values of the "Dynalog files" and the measured values of the ionization chamber. The mean values were (-1.11 + 2.42)%, (0.82 + 1.73)% and (-1.27 + 2.48)% and (0.56 + 1.91)%, which conformed to the clinical dosimetry requirements. The two sets of reconstruction values were paired with the measured values of the ionization chamber respectively. The results showed that the two groups were not statistically different from the ionization chamber measured values (t=1.91, -1.83, P0.05; t=2.01, -0.88, P0.05). As mentioned above, the correct and reasonable method of using EPID to control the quality of dosimetry for advanced radiotherapy technology does not affect treatment and is easy to spread. It not only improves the efficiency of dose verification before treatment, but also has a great advantage in real-time monitoring the patient's dose of radiotherapy. It is helpful to carry out patient dose verification. The accurate method of "Dynalog files" reconstruction dose is simple and can be supplemented with the measurement method, providing a reference for the formation of a fast and simple advanced radiotherapy technology dose monitoring method.

【學(xué)位授予單位】：中國疾病預(yù)防控制中心
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：R730.55

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 孟慧鵬;董化江;丁紅軍;孫小U，

本文編號(hào)：1878602