本文選題：重離子治療 + 調(diào)強(qiáng)放療��； 參考：《中國科學(xué)院大學(xué)(中國科學(xué)院近代物理研究所)》2017年碩士論文

【摘要】：重離子束(heavy ion beam)相比于放射治療常用射線(光子)主要有兩方面優(yōu)勢:在物理學(xué)上重離子具有倒轉(zhuǎn)的深度劑量分布,即Bragg曲線,可以通過對束流能量的調(diào)節(jié)實(shí)現(xiàn)對腫瘤靶區(qū)高劑量的精確輻照,并且重離子束在穿越人體組織時(shí)能量損失小使入射通道上的正常組織受到較少的劑量;在生物學(xué)上重離子束在Bragg峰區(qū)具有高的傳能線密度(linear energy transfer,LET)因而具有高的相對生物學(xué)效應(yīng)(relative biological effectiveness,RBE),而在坪區(qū)的LET較低,其生物學(xué)效應(yīng)與常規(guī)放療中的X射線相似,可以保證對腫瘤靶區(qū)具有高劑量輻照的同時(shí)實(shí)現(xiàn)對附近正常組織和危及器官(organ at risk,OAR)的有效保護(hù)。因此基于以上兩方面優(yōu)勢,重離子束被譽(yù)為二十一世紀(jì)的最佳放療用射線。在傳統(tǒng)的光子放療中,基于逆向計(jì)劃(inverse planning)的調(diào)強(qiáng)放療(Intensity Modulated Radiation Therapy,IMRT)逐漸發(fā)展成為一種成熟的治療技術(shù)而被廣泛應(yīng)用于各大放射治療中心。IMRT通過調(diào)節(jié)入射束流的強(qiáng)度對靶區(qū)進(jìn)行非均勻照射,不同入射方向的束流疊加最終得到理想的劑量分布,相比于正向計(jì)劃而言,對腫瘤靶區(qū)的輻照強(qiáng)度與對正常組織或危機(jī)器官的保護(hù)效果都得到了極大的提高。并且隨著技術(shù)的發(fā)展與日益完善,不斷有新的調(diào)強(qiáng)技術(shù)被提出,其中Shepard教授提出的基于模擬退火原理的直接射野孔徑優(yōu)化(direct aperture optimization,DAO)算法可以實(shí)現(xiàn)對照射野(beam’s eye view,BEV)方向上多葉光柵(Multileaf Collimator,MLC)葉片位置與孔徑權(quán)重的同時(shí)優(yōu)化,在優(yōu)化子野時(shí)不再需要預(yù)先計(jì)算出強(qiáng)度通量圖(intensity map),達(dá)到通過較少子野數(shù)量即可實(shí)現(xiàn)高度適形的照射效果。但是在重離子治療中,真正意義上的調(diào)強(qiáng)技術(shù)仍未實(shí)現(xiàn),因此為了將常規(guī)放療中的DAO-IMRT技術(shù)應(yīng)用到重離子治療中來,本論文基于被動(dòng)式束流配送系統(tǒng)開展了一系列針對改進(jìn)DAO模型的模擬研究,發(fā)展基于DAO原理的重離子放射治療技術(shù)�？紤]到光子與重離子束流模型的區(qū)別,本論文工作在每個(gè)BEV方向上提出縱向分層的概念,并考慮重離子治療的橫向散射因素建立高斯形束流模型,對不同的靶區(qū)模型進(jìn)行模擬優(yōu)化得到一系列較為理想的優(yōu)化結(jié)果。結(jié)果顯示重離子治療中基于DAO原理的劑量優(yōu)化可以實(shí)現(xiàn)使用少量子野達(dá)到較高的劑量適形效果,直接得到每個(gè)子野的MLC葉片位置與相應(yīng)的權(quán)重。對于標(biāo)準(zhǔn)的凹形靶體(TG119測試模型的簡化模型),本論文工作模擬了多個(gè)BEV方向束流的疊加照射,結(jié)果顯示在基于被動(dòng)式束流配送系統(tǒng)重離子治療下可以初步實(shí)現(xiàn)調(diào)強(qiáng)放療技術(shù)。在對展寬布拉格峰(spread-out Bragg peak,SOBP)縱向展寬的研究中,考慮到放射生物學(xué)模型中RBE隨深度的變化對腫瘤靶區(qū)生物有效劑量的影響,在被動(dòng)式束流配送系統(tǒng)下采用基于不同展寬的微型脊型過濾器(mini ridge filter,mini-RF)的雙微小展寬峰(mini-SOBP)組合照射方法針對重離子的分層照射治療方式進(jìn)行優(yōu)化。理論計(jì)算顯示對于不同初始能量的12C離子束,利用較大和較小兩種半高寬(full width at half maximum,FWHM)的mini-SOBP組合疊加,得到了按生物有效劑量和物理吸收劑量均勻兩種方式展寬的SOBP,實(shí)現(xiàn)了在減少照射分層數(shù)縮短治療時(shí)間的同時(shí),減小SOBP遠(yuǎn)端劑量跌落距離(distal dose fall-off distance,通常為SOBP遠(yuǎn)端劑量80%-20%之間的縱向距離),使腫瘤靶區(qū)后方正常組織或危及器官得到最大程度的保護(hù)。
[Abstract]:The heavy ion beam (heavy ion beam) has two main advantages compared with the radiation therapy of radiation (photons). In physics, the heavy ion has a deep dose distribution in reverse, that is, the Bragg curve. The high dose of the tumor target area can be accurately irradiated by the regulation of the beam energy, and the heavy ion beam is energy through the body tissue. The low loss caused the normal tissue on the incident channel to be less dose; the biological heavy ion beam has a high energy transfer line density (linear energy transfer, LET) in the Bragg peak region, thus having a high relative biological effect (relative biological effectiveness, RBE), while the LET of the plateau region is low, and its biological effect and conventional radiotherapy Similar to the X ray, it can ensure the high dose radiation of the tumor target area and the effective protection of the nearby normal tissue and the endanger organ (organ at risk, OAR). Therefore, based on the above two advantages, the heavy ion beam is known as the best radiotherapy line in twenty-first Century. In the traditional photon radiotherapy, the reverse plan (INV) is based on the reverse plan (INV). Erse planning (Intensity Modulated Radiation Therapy, IMRT) has gradually developed into a mature treatment technology and is widely used in large radiation therapy center.IMRT to irradiate the target region by adjusting the intensity of incident beam, and the ideal dose distribution is finally obtained by the superposition of the beam of different incident directions. Compared with the forward plan, the radiation intensity of the tumor target area and the protection effect on the normal tissue or the crisis organ have been greatly improved. And with the development and improvement of the technology, the new technique of intensity modulation has been put forward, in which the direct field aperture optimization based on the simulated annealing principle is proposed by Professor Shepard (direc The T aperture optimization, DAO) algorithm can achieve the simultaneous optimization of the position of the multileaf raster (Multileaf Collimator, MLC) blade and the weight of the aperture in the direction of the contrast field (beam 's eye view, BEV). The intensity flux graph is no longer needed in the optimization of the subfield. However, in heavy ion therapy, the true intensity modulation technology is still not realized, so in order to apply the DAO-IMRT technology in conventional radiotherapy to heavy ion therapy, this paper develops a series of simulated research on the improved DAO model based on the passive beam distribution system, and develops heavy ions based on the principle of DAO. Radiation therapy technology. Considering the difference between photon and heavy ion beam model, this paper proposes the concept of longitudinal stratification in every BEV direction, and considers the Gauss beam model for the transverse scattering factors of heavy ion therapy. A series of more ideal optimization results are obtained by simulating and optimizing the different target area models. The results show that the results show a series of ideal results. The dose optimization based on the DAO principle in the heavy ion therapy can achieve a high dose conformal effect with a small number of subfields, and directly obtain the MLC blade position and the corresponding weight of each subfield. For the standard concave target (the simplified model of the TG119 test model), the work of this paper simulates the superposition of multiple BEV direction beams. The results show that the intensity modulated radiation therapy can be implemented initially under the heavy ion therapy based on the passive beam distribution system. In the study of the longitudinal broadening of the spread-out Bragg peak (peak, SOBP), the effect of RBE on the biological effective dose of the tumor target area in the radibiologic model is taken into account in the passive beam flow distribution. The double micro broadening peak (mini-SOBP) combined irradiation method based on the mini ridge filter (mini-RF) based on the transmission system is used to optimize the treatment of stratified irradiation of heavy ions. The theoretical calculation shows that the 12C separated beams with different initial energy use two large and smaller half wide width (full width a). The mini-SOBP combination of T half maximum and FWHM is superimposed, and the SOBP is broadened in two ways, namely, the biological effective dose and the physical absorption dose. It reduces the distance of the SOBP distal dose drop distance (distal dose fall-off distance, usually between the distal SOBP dosages) while reducing the treatment time for reducing the number of radiation stratification. To the distance, the normal tissue or organ endangering the tumor target area can be protected to the greatest extent.

【學(xué)位授予單位】：中國科學(xué)院大學(xué)(中國科學(xué)院近代物理研究所)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：R730.55;TP18

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 姬騰飛;劉新國;戴中穎;賀鵬博;閆淵林;黃齊艷;李強(qiáng);;重離子放射治療雙微小展寬峰組合照射方法[J];原子核物理評論;2016年03期

2 肖國青;張紅;李強(qiáng);宋明濤;詹文龍;;中國科學(xué)院近代物理研究所重離子束治癌進(jìn)展[J];原子核物理評論;2007年02期

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