本文選題：數(shù)字化X射線攝影 + 劑量指示值��； 參考：《復(fù)旦大學(xué)》2013年碩士論文

【摘要】：[目的]在醫(yī)用X射線診斷中,數(shù)字化X射線攝影已逐漸取代傳統(tǒng)的屏片式X射線攝影。本課題旨在通過研究數(shù)字化X射線攝影裝置中的劑量指示值與受檢者入射體表劑量、器官劑量和全身有效劑量之間的定量關(guān)系,建立用于快速估算數(shù)字化X射線攝影中受檢者劑量的模式與方法,為開展醫(yī)療照射的劑量調(diào)查與集體劑量評估提供有效手段。 [方法]基于數(shù)字化X射線攝影(CR)裝置中的劑量指示值,提出數(shù)字化X射線攝影中受檢者入射體表劑量估算的理論模型,進一步重點探討CR系統(tǒng)中管電壓、總濾過和受檢部位體厚這三個因素對估算模型的影響,建立劑量指示值與受檢者入射體表劑量之間的定量關(guān)系模式；通過水模體實驗測量和蒙特卡羅模擬計算確定模型中包括體厚衰減函數(shù)和成像板能量響應(yīng)在內(nèi)的相關(guān)參數(shù)。模型的普適性驗證在三臺X射線發(fā)生裝置不同的攝影系統(tǒng)上進行,主要運用熱釋光劑量元件測量腹部正位攝影中受檢者入射體表劑量；此外,還將本研究所建立的劑量指示值模型與曝光參數(shù)法、劑量面積乘積法比較,對比不同估算模式之間的差異。運用最新版本的MIRD數(shù)學(xué)模型和蒙特卡羅模擬計算軟件MCNP5,開展受檢者器官劑量和有效劑量的模擬計算,以取得不同攝影檢查、不同管電壓、不同總濾過條件下,受檢者入射體表劑量-器官劑量的轉(zhuǎn)換因子；并通過與已有入射體表劑量-器官劑量轉(zhuǎn)換因子的比較,驗證本研究所得轉(zhuǎn)換因子的有效性。在此轉(zhuǎn)換因子的基礎(chǔ)上,結(jié)合最新的組織權(quán)重因子,進一步計算受檢者的有效劑量,得出入射體表劑量-有效劑量的轉(zhuǎn)換因子。最后,結(jié)合本研究所建立的入射體表劑量估算模型和入射體表劑量-有效劑量轉(zhuǎn)換因子,給出通過劑量指示值估算有效劑量的方法。 [結(jié)果]本研究建立了利用劑量指示值估算數(shù)字化X射線攝影所致受檢者入射體表劑量和有效劑量的數(shù)學(xué)模式。驗證實驗結(jié)果表明,利用本研究建立的方法估算得到的受檢者入射體表劑量與實際測量值的相對偏差介于-16.9%到至18.1%之間,且該方法的估算值與其他方法的計算結(jié)果也相近。本研究計算得到的入射體表劑量與器官劑量的轉(zhuǎn)換因子,對主射線束內(nèi)器官而言與已有文獻報道值的相對偏差在-28.6%到24.8%之間。在組織權(quán)重因子相同的條件下,本研究所得出的入射體表劑量與有效劑量的轉(zhuǎn)換因子與已有文獻報道值相對偏差在-12.5%到3.2%之間,兩者吻合良好。 [結(jié)論]本研究所建立的數(shù)字化X射線攝影所致受檢者劑量估算模式的計算結(jié)果,基本能滿足輻射防護劑量學(xué)評價的精度要求。該估算模式可借助劑量指示值,管電壓及受檢部位厚度,直接估算某類數(shù)字化X射線攝影檢查中受檢者的入射體表劑量、主要器官的吸收劑量和全身有效劑量。可為數(shù)字化X射線診斷中受檢者劑量的現(xiàn)狀或回顧性調(diào)查提供了一種便捷且有效的方法與手段。
[Abstract]:Objective: in medical X-ray diagnosis, digital X-ray photography has gradually replaced the traditional screen-type X-ray photography. The purpose of this paper is to study the quantitative relationship between the dose indication value in the digital X-ray camera and the incident surface dose, organ dose and the effective dose of the whole body. To establish a model and method for rapid estimation of dose of subjects in digital X-ray photography, and to provide an effective means for carrying out dose investigation and collective dose assessment of medical exposure. [methods] based on the dose indication in the digital X-ray radiography system, a theoretical model for estimating the incident dose of the person tested in digital X-ray photography is proposed, and the tube voltage in the CR system is further discussed. The influence of three factors, total filtration and body thickness, on the estimation of the model, and the quantitative relationship between the dose indicator and the incident dose of the body surface were established. The parameters of the model including the attenuation function of body thickness and the energy response of the imaging plate are determined by the measurement of the water model and the Monte Carlo simulation. The universal validation of the model is carried out on three different radiographic systems. The thermoluminescence dose elements are mainly used to measure the incident surface dose of the subjects in orthotopic abdominal photography. The dose indicator model is compared with the exposure parameter method and the dose area product method, and the differences between different estimation models are compared. The latest version of MIRD mathematical model and Monte Carlo simulation software MCNP5 are used to simulate and calculate organ dose and effective dose in order to obtain different photographic examination, different tube voltage and different total filtering conditions. The conversion factor of incident surface dose to organ dose is verified by comparing with the existing incident surface dose-organ dose conversion factor. On the basis of this conversion factor and the latest tissue weight factor, the effective dose of the subject is further calculated, and the conversion factor between the incident surface dose and the effective dose is obtained. Finally, a method to estimate the effective dose through the dose indication is given, which is based on the incident surface dose estimation model and the incident surface dosis-effective dose conversion factor. [results] A mathematical model was established to estimate the incident dose and effective dose of the subjects induced by digital X-ray photography. The experimental results show that the relative deviation between the estimated incident dose and the actual measured value is between -16.9% and 18.1%, and the estimated value of this method is similar to that of other methods. In this study, the relative deviation between the incident body surface dose and the organ dose was -28.6% to 24.8% for the organs in the main ray beam. Under the condition of the same tissue weight factor, the relative deviation between the incident surface dose and the effective dose is -12.5% to 3.2%, which is in good agreement with the reported values. [conclusion] the calculated results of the dose estimation model established by this study can basically meet the requirements of radiation protection dosimetry evaluation. With the aid of dose indication, tube voltage and site thickness, the model can directly estimate the incident body surface dose, the absorbed dose of the main organs and the effective dose of the whole body in a kind of digital X-ray examination. It can provide a convenient and effective method for the present situation or retrospective investigation of dose in digital X-ray diagnosis.
【學(xué)位授予單位】：復(fù)旦大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：R814.2

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