本文選題：基于梯度的形變配準 + IMRT　； 參考：《山東師范大學》2017年碩士論文

【摘要】：放射治療是目前最為流行且有效的腫瘤治療方法,由于IMRT具有陡峭的劑量跌落梯度,精準的劑量調(diào)節(jié),更好的危及器官保護能力,所以廣泛應(yīng)用在頭頸部腫瘤放射治療當中。臨床上,癌癥患者的治療周期一般為6-7周,在此期間,癌癥病人的體重變化,以及腫瘤體積的變化等因素很可能導致靶區(qū)、OARs的解剖結(jié)構(gòu)發(fā)生變化。如果繼續(xù)使用原始計劃做放射治療,就會使靶區(qū)劑量降低,危及器官劑量升高,進而促使正常組織受到射線的損傷,增加并發(fā)癥發(fā)生概率,大大降低病人的生活質(zhì)量。基于以上情況,目前臨床上采取的措施是在腫瘤患者每次放射治療前,進行CT或者CBCT掃描來指導擺位,治療3-4周時修改一次治療計劃。然而僅僅修改一次計劃還不能很好的彌補癌癥患者靶區(qū)、OARs的解剖結(jié)構(gòu)變化對劑量分布造成的嚴重影響。因此本論文針對目前臨床上存在的上述疑難問題,設(shè)計四種自適應(yīng)IMRT調(diào)整方案,巧妙運用基于梯度的形變配準方法,解決臨床放療中的難題,主要內(nèi)容概括為以下兩個方面:(1)基于梯度的形變配準方法的研究本論文針對CBCT圖像密度分辨率低,以及CBCT圖像與CT圖像密度不一致的問題,提出了一種基于梯度的形變配準方法。本部分首先對CT與CBCT圖像的成像原理,成像特點展開了論述,并針對以上兩種圖像的特點,構(gòu)建空間形變模型,設(shè)計高效的形變配準方法,并運用臨床病人數(shù)據(jù)對該方法進行了實驗驗證分析,為了進一步證明該形變配準方法的有效性及可行性,本論文將基于梯度的配準算法與配準領(lǐng)域內(nèi)公認的“金標準”Demons形變配準算法進行了對比試驗、分析。(2)四種頭頸部腫瘤自適應(yīng)IMRT調(diào)整方案的對比研究本論文,首先選取28例頭頸部腫瘤患者進行試驗研究,所有腫瘤患者均接受常規(guī)分割治療。在放療周期內(nèi),選取患者各個放療周第1天掃描獲取的CBCT圖像(共6周)作為參考圖像,計劃CT圖像作為目標圖像,將兩者形變配準后的圖像定義為“偽CT”圖像。其次,設(shè)計四種不同頻次計劃調(diào)整方案,無計劃調(diào)整作為參考方案,定義每種方案的實際劑量與計劃調(diào)整劑量,并在所得到的6套“偽CT圖像”上重新計算劑量,并運用基于密度的形變配準算法進行單周分次劑量的疊加,計算得到每種計劃調(diào)整方案的累加實際劑量與計劃調(diào)整劑量。最后,量化評估放療周期期間腫瘤靶區(qū)、OARs體積與劑量的變化,并分別統(tǒng)計分析兩者的變化規(guī)律,以及兩者變化之間的相關(guān)性。最終得出結(jié)論:再計劃可確保靶區(qū)足夠劑量,使危及器官受量控制在安全范圍內(nèi),再計劃頻次越高,實際劑量越接近計劃調(diào)整劑量,2次再計劃方案效率最高。
[Abstract]:Radiation therapy is the most popular and effective method of cancer treatment. Because IMRT has a steep dose drop gradient, accurate dose regulation, and better endanger the organ protection, it is widely used in head and neck cancer radiotherapy. In clinical, cancer patients are usually treated for 6-7 weeks. During this period, cancer patients The changes in body weight and tumor volume may lead to the changes in the anatomical structure of the OARs. If the original plan is used for radiation therapy, the dose of the target area will be reduced and the dose of the organ is increased. Then the normal tissue is damaged by radiation, the probability of complication is increased, and the patient is greatly reduced. Quality of life. Based on the above situation, the current clinical measures are to conduct CT or CBCT scans before each radiotherapy for the cancer patients to guide the pendulum, and to modify a treatment plan at 3-4 weeks. However, only a revision of the plan can not make up for the target area of the cancer patients, and the changes of the anatomical structure of OARs to the dose distribution In this paper, four adaptive IMRT adjustment schemes are designed to solve the difficult problems existing in the clinic and apply the gradient based deformation registration method to solve the problems in clinical radiotherapy. The main contents are as follows: (1) research on the paper based on the gradient based deformation registration method. For the low density resolution of CBCT image and the disagreement between the CBCT image and the density of the CT image, a gradient based deformation registration method is proposed. This part first discusses the imaging principle of CT and CBCT images and the imaging characteristics, and constructs a spatial deformation model for the characteristics of the above two images, and designs a highly effective deformation registration. In order to further prove the validity and feasibility of the deformation registration method, this paper makes a comparative experiment based on the gradient registration algorithm and the recognized "gold standard" Demons deformation registration algorithm in the field of registration. (2) four kinds of head and neck tumors. A comparative study of the adaptive IMRT adjustment scheme, 28 cases of head and neck tumors were selected and all the patients received routine segmentation. During the radiotherapy period, the CBCT images (6 weeks) obtained by the first day scans of each radiotherapy week were selected as the reference images, and the CT images were planned as the target images, and two were planned. The image after deformation registration is defined as "pseudo CT" image. Secondly, four different frequency planning schemes are designed, without planned adjustment as a reference scheme, the actual dose and planned dose of each scheme are defined, and the dosage is recalculated on the 6 set of "pseudo" images, and the density based deformation registration algorithm is used. On the basis of the superposition of the single weekly dose, the cumulative actual dose and the planned adjusted dose of each plan adjustment scheme were calculated. Finally, the changes of the tumor target area, OARs volume and dose during the radiotherapy period were quantified, and the changes of the two changes were statistically analyzed, and the correlation between the two changes were analyzed. Finally, the conclusion was drawn. It can ensure that the target area is sufficient enough to control the organ tolerance within the safe range. The more the planned frequency is higher, the more the actual dose is closer to the planned adjustment dose, the 2 re plan is the most efficient.
【學位授予單位】：山東師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：R739.91;TP391.41

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相關(guān)期刊論文 前1條

1 曹建忠;羅京偉;徐國鎮(zhèn);高黎;肖建平;李素艷;易俊林;黃曉東;;鼻咽癌調(diào)強放療中解剖及劑量學改變再次計劃必要性研究[J];中華放射腫瘤學雜志;2008年03期

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本文編號：2084326