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  本文關鍵詞： 高本底 小劑量 γ能譜 無源效率刻度 器官劑量 外照射　出處：《中國疾病預防控制中心》2012年碩士論文　論文類型：學位論文

【摘要】：為了研究長期小劑量、低劑量率電離輻射對人體健康的影響,特別是小劑量電離輻射對不同部位患癌危險度的影響,陽江天然高本底地區(qū)天然放射性高本底輻射與居民健康研究已經開展了近40年,輻射劑量學的研究伴隨整個研究過程,也已取得較多的劑量學測量數(shù)據(jù),本研究作為陽江天然高本底地區(qū)劑量學研究的延續(xù),探尋外照射所致居民器官劑量學研究的新方法,以期對器官劑量進行較為準確的估算,以更好的分析劑量——效應關系。 本研究使用ORTEC DETECTIVE-DX-100T型HPGe γ能譜儀對高本底地區(qū)和對照地區(qū)居民所處環(huán)境Y能譜的測量,根據(jù)照射的實際情況經過適當簡化,建立適當?shù)恼丈淠Ｐ?模擬實際環(huán)境對居民的輻射照射情況,通過無源效率刻度的方法計算所建立的照射模型下γ能譜儀探頭的探測效率刻度曲線,經過γ能譜解譜分析(能量刻度選擇天然放射性核素6個能量點進行刻度,效率刻度使用無源效率刻度軟件對所用照射模型下的刻度曲線進行計算),計算出該模型中核素的分布、構成以及各自活度。根據(jù)模型的空間結構和核素的活度計算出參考點(相對于模型中HPGeγ能譜儀晶體中心)處的空氣比釋動能率,最后根據(jù)照射的實際情況確定照射的幾何條件,選用適當?shù)膯挝豢諝獗柔寗幽艿狡鞴傥談┝康霓D換系數(shù)計算出不同器官的吸收劑量。 根據(jù)高本底地區(qū)劑量學調查中劃分的高、中、低劑量組和對照組共4個劑量組,分組選取4個鎮(zhèn)的1到2個村莊作為研究對象,對照地區(qū)選取高本底地區(qū)劑量學調查結果中年吸收劑量最低的村莊,高本底地區(qū)高、中、低劑量組選取年吸收劑量在該組中的最高的村莊,以盡量拉開各劑量組間的差別。每個劑量組選取建筑材料為土、石頭、磚的住宅各4間分別進行測量(部分村莊由于實際條件限制土房和石頭房不足4間),每個劑量組選取一個室外測量點進行測量。整個研究共對46個測量點進行了現(xiàn)場Y能譜的測量,其中高本底地區(qū)室內30個點、室外3個點,對照地區(qū)室內12個點、室外1個點。每個劑量組室外測量點進行土壤樣品的采集并進行實驗室γ能譜分析,確定土壤中天然放射性核素的構成。另外,所有的測量點均使用6150AD6/h+6150AD b/h型便攜X/γ劑量率儀對測量點的劑量率進行了測量,測量結果與γ能譜方法計算結果進行驗證。 通過γ能譜方法所計算的空氣比釋動能率和X/γ劑量率儀所測得的劑量率歸一到同一物理量進行統(tǒng)計分析,結果表明分析結果很好的符合了實際照射條件和所建立的照射模型的一致性,證實了對實際照射條件進行簡化的可行性。 本研究使用γ能譜方法,分析出圓柱形有底面源模型和圓面源模型中天然放射性核素的構成及活度,使用CRAM模型ROT照射幾何條件的轉換系數(shù),結合以往流行病調查中的居民居室內居留因子(0.698),計算了外照射所致陽江高本底地區(qū)和對照地區(qū)各劑量組不同類型住宅的居民器官吸收劑量和全身有效劑量。
[Abstract]:In order to study the long-term small dose, low dose rate effects of ionizing radiation on human health, especially small doses of ionizing radiation effect on cancer risk in different parts of the Yangjiang natural high background area of high natural background radiation and health of residents has been carried out for nearly 40 years, the research of radiation dosimetry with the entire course of the study. It has been made more dosimetric measurement data, this study as a natural continuation of the high background of Yangjiang dosimetric study area, to explore a new method to study the dosimetric external irradiation caused by the residents, in order to estimate the organ dose for more accurate, to better analyze the dose effect relationship.
This study uses the ORTEC DETECTIVE-DX-100T type HPGe gamma spectrometer to measure the high background area and control area residents environment Y spectrum, according to the actual situation of irradiation after appropriate simplification, establish a proper model for simulation of radiation exposure, exposure to the residents of the actual environment, the detection efficiency calibration curve model established by irradiation method sourcelessefficiencycalibration calculated the gamma ray spectrometer probe, the gamma ray spectrum analysis (energy scale selection of natural radionuclide 6 energy points scale, efficiency calibration using passive efficiency calibration software for calibration curve is calculated under the irradiation model), calculate the distribution of radionuclide in the model. Composition and their activity. The calculated reference points according to the spatial structure and activity model of nuclide (relative to the model HPGe gamma spectrometer crystal center) at the air kerma rate, the most The geometric condition of irradiation is determined according to the actual situation of radiation. The absorbed dose of different organs is calculated by selecting the appropriate conversion coefficient of the unit air specific kinetic energy to the organ absorbed dose.
According to the high background area investigation division of the high dose, and low dose group and control group were 4 dose group, grouping and selecting 4 towns 1 to 2 villages as the research object, the control area from HBRA dosimetric survey results of middle-aged village lowest absorption dose, high background area. In the low dose group selected years absorbed dose in the group with the highest village, to try to pull the difference between each dose group. Each dose group selected building materials for soil, stone, brick houses of the 4 measured (part of the village due to lack of actual conditions and a 4 room stone house) each group selected a dose, the outdoor measurement spot. The research includes the measurement of Y spectrum of 46 measurement points, the high background area indoor 30 points, outdoor 3 points, 12 points control area indoor, outdoor 1 points. Each dose group of outdoor Spectrum analysis laboratory measurement points of soil samples collected and determine the composition of natural radionuclides in soil. In addition, all measurement points are used 6150AD6/h+6150AD b/h type portable X/ gamma dose rate instrument of measuring points were measured, the measurement results with the gamma spectrum method was validated.
By gamma spectrum method calculation of the air kerma rate and X/ dose rate meter measured the gamma dose rate was normalized to the same physical quantity statistical analysis, results show that the results fit well with the consistency of the actual conditions and the irradiation irradiation model, proved the feasibility of the actual conditions the irradiation was simplified.
This study uses the gamma spectrum analysis method, composition and activity of natural radionuclide bottomed cylindrical surface source model and the round surface source model, the conversion coefficient using the CRAM model ROT irradiation geometry conditions, combined with previous epidemiological survey of residents living within the residence factor (0.698), external radiation caused by the high background radiation area of Yangjiang and the control groups of different types of residential area residents organ absorbed dose and effective dose were calculated.

【學位授予單位】：中國疾病預防控制中心
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：R144

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本文編號：1539397