【摘要】：論文以我國(guó)自行研制并已投入臨床使用的LunaTM-260全身伽瑪?shù)吨委煓C(jī)為對(duì)象,研究了該伽瑪?shù)秵卧春投嘣吹撵o態(tài)聚焦的劑量學(xué)特性。目的,建立Luna伽瑪?shù)兜拿商乜_劑量計(jì)算模型,模擬計(jì)算伽瑪?shù)秳┝繉W(xué)參數(shù)。解決Luna伽瑪?shù)对谂R床使用中單源的百分深度劑量(PDD)、組織最大劑量比(TMR)、射野離軸比(OAR)及輸出因子等劑量學(xué)參數(shù)無(wú)法測(cè)量的問(wèn)題,并將蒙卡計(jì)算結(jié)果與治療計(jì)劃系統(tǒng)的數(shù)據(jù)比較,對(duì)驗(yàn)證伽瑪?shù)吨委煹膭┝繙?zhǔn)確性進(jìn)行驗(yàn)證。 課題涉及伽瑪?shù)稒C(jī)頭的幾何建模、膠片劑量計(jì)的實(shí)驗(yàn)測(cè)量、蒙特卡羅程序的模擬計(jì)算等工作。論文介紹并論述了目前伽瑪?shù)队?jì)劃系統(tǒng)的劑量計(jì)算模型及優(yōu)缺點(diǎn)以及蒙特卡羅方法的基本原理。著重論述了Luna伽瑪?shù)队?jì)劃系統(tǒng)采用的TMR-OAR劑量計(jì)算模型,涉及到的一些劑量學(xué)參數(shù),討論了蒙特卡羅程序MCNP4C對(duì)開(kāi)展本研究的可行性和實(shí)用性。詳述了基于Luna伽瑪?shù)兜臋C(jī)頭結(jié)構(gòu)、材料和尺寸,以及放射源的特征的MCNP劑量計(jì)算模型的幾何建模。并通過(guò)與測(cè)量數(shù)據(jù)的比較來(lái)驗(yàn)證計(jì)算模型的正確性,基于所建劑量計(jì)算模型開(kāi)展伽瑪?shù)秵卧春投嘣淳劢沟膭┝繉W(xué)研究。伽瑪?shù)兜膶?shí)驗(yàn)測(cè)量采用Gafchromic EBT2新型膠片劑量計(jì)。 研究方法：通過(guò)建立伽瑪?shù)秳┝坑?jì)算模型,分別計(jì)算單源和多源射束所有準(zhǔn)直器在30cm×30cm×30cm水模體中的劑量參數(shù)和在直徑16cm的伽瑪?shù)秾?zhuān)用有機(jī)玻璃球模中的等劑量分布。 結(jié)果：模擬計(jì)算了luna伽瑪?shù)?種準(zhǔn)直器(4mm×4mm、8mm×8mm、14mm×14mm、14mm×20mm、14mm×40mm、14mm×60mm)單源和多源的在水模中的0.5cm、5cm及10cm深度出處的百分深度劑量及離軸比；計(jì)算了在專(zhuān)用測(cè)量球模中的等劑量分布曲線(xiàn)。在水模0.5cm深度處4、5、6號(hào)準(zhǔn)直器的射野離軸比計(jì)算結(jié)果不好；5cm和10cm處的計(jì)算結(jié)果比較理想。根據(jù)百分深度劑量與組織最大劑量比的關(guān)系,由百分深度劑量數(shù)據(jù)得到組織最大劑量比的值。將單源方模中的組織最大劑量比的計(jì)算結(jié)果、計(jì)劃系統(tǒng)中的原始數(shù)據(jù)(測(cè)量數(shù)據(jù))及標(biāo)準(zhǔn)的組織最大劑量比曲線(xiàn)進(jìn)行了比較：計(jì)算結(jié)果與標(biāo)準(zhǔn)曲線(xiàn)符合的較好,與TPS中數(shù)據(jù)(測(cè)量)有一定誤差,最大誤差不超過(guò)5%。對(duì)于l號(hào)準(zhǔn)直器在0—5cm深度范圍計(jì)算值比測(cè)量值大,5—15cm深度范圍計(jì)算值與測(cè)量值基本一致,大于15cm的深度計(jì)算值比測(cè)量值��；對(duì)于其余的5個(gè)準(zhǔn)直器計(jì)算值與測(cè)量值一致,測(cè)量值大于計(jì)算值,誤差為2%-5%。單源方模中5cm深度處射野離軸比的比較結(jié)果：射野內(nèi)的數(shù)值符合的較好,射野外的數(shù)值相差較大。每個(gè)準(zhǔn)直器取其焦點(diǎn)處的劑量作為標(biāo)準(zhǔn)值,以6號(hào)準(zhǔn)直器最為標(biāo)準(zhǔn)歸一計(jì)算了6個(gè)準(zhǔn)直器的輸出因子,將其與測(cè)量結(jié)果比較。1號(hào)準(zhǔn)直器相差較大(大于10%),其余均小于3%。 結(jié)論：所建立的蒙特卡羅計(jì)算模型很好地驗(yàn)證了單源射野的百分深度劑量(PDD)、組織最大劑量比(TMR)、射野離軸比(OAR)及輸出因子,計(jì)算結(jié)果與測(cè)量結(jié)果在誤差范圍(5%)內(nèi)符合的很好；同時(shí),對(duì)于多源聚焦的劑量分布特點(diǎn)進(jìn)行了研究,給出luna伽瑪?shù)兜慕裹c(diǎn)劑量分布。研究結(jié)果表明所建立的luna伽瑪?shù)睹商乜_劑量計(jì)算模型可以用于其劑量學(xué)參數(shù)的驗(yàn)證,很好地解決了單源劑量學(xué)參數(shù)無(wú)法測(cè)量的問(wèn)題,同時(shí)對(duì)于伽瑪?shù)兜呐R床上計(jì)劃設(shè)計(jì)和劑量計(jì)算起到一定的指導(dǎo)性作用。本工作為伽瑪?shù)督窈笱芯抗ぷ鞯於嘶A(chǔ)。
[Abstract]:The dosimetric characteristics of single-source and multi-source static focusing of LunaTM-260 gamma knife were studied. Objective To establish a Monte Carlo dosimetric model of Luna gamma knife and simulate the dosimetric parameters of Luna gamma knife. The dosimetric parameters such as PDD, TMR, OAR and output factor can not be measured. The results of Monte Carlo simulation were compared with the data of treatment planning system to verify the dose accuracy of gamma knife therapy.
The subject involves the geometric modeling of gamma knife head, the experimental measurement of film dosimeter and the simulation calculation of Monte Carlo program. The paper introduces and discusses the dose calculation model, advantages and disadvantages of the current gamma knife planning system and the basic principle of Monte Carlo method. The TMR-OAR used in Luna gamma knife planning system is emphatically discussed. The feasibility and practicability of the Monte Carlo program MCNP4C for this study are discussed. The geometric modeling of the MCNP dose calculation model based on Luna gamma knife is described in detail, including the structure, material and size, and the characteristics of the radiation source. Based on the correctness of the calculation model, single-source and multi-source focused gamma knife dosimetry was carried out. Gafchromic EBT2 film dosimeter was used in the experimental measurement of gamma knife.
Research methods: By establishing gamma knife dose calculation model, the dose parameters of all collimators of single source and multi-source beam in 30 cm 65507
Results: The percentile depth doses and off-axis ratios of 6 kinds of Luna gamma knife collimators (4 mm 4 mm, 8 mm 8 mm, 14 mm 14 mm, 14 mm 65 According to the relationship between the percentage depth dose and the maximum dose ratio of tissue, the maximum dose ratio of tissue can be obtained from the percentage depth dose data. Comparing the measured data with the standard tissue maximum dose ratio curve, the calculated results are in good agreement with the standard curve, and the maximum error is less than 5% with the TPS data. The calculated depth at 15 cm is smaller than the measured value, and the measured value is larger than the calculated value for the remaining 5 collimators, with an error of 2%-5%. The comparison of the off-axis ratio of the field at the depth of 5 cm in a single source square model shows that the values in the field are in good agreement with those in the field, and the values in the field are quite different. The output factors of the six collimators were normalized by using collimator No. 6 as the standard value. The difference between collimator No. 1 and the measured results was larger (more than 10%) and the rest was less than 3%.
CONCLUSION: The Monte Carlo calculation model validates the PDD, TMR, OAR and output factor of single source radiation field. The calculated results are in good agreement with the measured results within the error range (5%). The results show that the Monte Carlo dose calculation model of Luna gamma knife can be used to validate the dosimetric parameters of Luna gamma knife. It can solve the problem that single source dosimetric parameters can not be measured. It also plays a guiding role in clinical planning and dose calculation of Luna gamma knife. This work lays the foundation for future research work of gamma knife.
【學(xué)位授予單位】：中國(guó)人民解放軍軍事醫(yī)學(xué)科學(xué)院
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2012
【分類(lèi)號(hào)】：R142

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本文編號(hào)：2191525