核设施流出物照射人体器官的当量剂量和有效剂量的 …

目的 研究在核设施流出物照射条件下ＩＣＲＰ６０喉出版物建议的新辐射量算法和有关参数，建立在核设施防护领域应用新辐射量的剂量学资料。方法 采用ＡＤＡＭ和ＥＶＡ拟人计算模型和组织－经的方法计算器官当量剂量和有效剂量。结果 给出了人核设施正常运行和事故时可能释放的近２００种核素，在空气浸没，水中浸没和地表沉积物３种照射方式下，器官当量剂量率因子和有效剂量率因子，考虑了男性１８种和女性２０种器官；有效剂量     

核设施流出物外照射下实用量与限值量关系的研究

目的　研究在核设施放射性流出物外照射条件下定向剂量当量Ｈ′（１０） 能否作为基本限值量有效剂量当量ＨＥ 和有效剂量Ｅ 的估计量。方法　用计算的方法确定流出物外照射的Ｈ′（１０）,ＨＥ 和Ｅ;采用ＡＤＡＭ 和ＥＶＡ两种拟人模型,考虑了男性１８ 种和女性２０ 种器官或组织。结果给出了空气浸没、水中浸没和地表沉积物３ 种照射方式下１８４ 种核素的Ｈ′（１０） 、人体器官剂量当量、ＨＥ 和Ｅ,分析了Ｈ′（１０） 与ＨＥ 和Ｅ之间的关系。结论　在核设施流出物外照射条件下,定向剂量当量可作为辐射防护基本限值量偏安全的估计量。     

一种可快速估算环境放射性污染所致公众外照射剂量的新软件

目的:开发便于快速估算环境放射性污染所致公众成员外照射剂量的应用软件。方法:基于国际放射防护委员会(ICRP)提供的数据,创建公众(成人与不同年龄组儿童)在不同环境暴露情形下的外照射剂量率转换系数数据库;在Windows操作系统内利用Python语言编写数据调用与计算程序,并借助PyQt工具包设计软件界面;为测试该软件的计算结果,试算了几种最可能出现放射性核素在3种环境暴露情景下所致公众成员的外照射剂量差异,并开展了合理性分析。结果:本研究开发软件可在带Windows系统的个人电脑上快速完成放射性核素污染外照射所致公众的器官当量剂量与全身有效剂量的估算,计算结果合理。结果表明,公众成员的年龄越小,器官当量剂量和有效剂量通常越大;对于相同活度浓度且达到放射性平衡 90Sr的土壤表面污染和水体污染,婴儿的有效剂量约为成人的6.08倍和2.51倍。 结论:本研究开发的软件具有操作简单、计算速度快等优点,适用于核事故应急等情形下快速估算公众成员外照射剂量。     

非均匀人形体模及医用诊断X线工作人员的有效剂量当量估算

本文根据ICRP有效剂量当量的概念,应用所研制的人干骨,干粉模拟软组织非均匀人形体模,求出了胃肠检查和胸透时医用诊断X线工作人员的器官剂量、有效剂量当量与个人剂量计读数的比值,也计算了它们与工作人员所在位置自由空气照射量率的比值。得出男女性别不同的医用诊断X线工作人员的有效剂量当量与佩戴在左胸的个人剂量计读数的比值,胃肠检查时分别为0.52和0.43,胸透时分别为0.32和0.21。应用这些比值和个人剂量监测数据估算了该类人员的有效剂量当量。     

X射线摄影所致受检者器官剂量-入射体表剂量转换系数的研究

目的 比较简单程式化数学模型(MIRD)与体素模型在常见X射线摄影下得到的器官剂量-入射体表剂量的转换系数差异。方法 利用蒙特卡罗模拟技术,分别模拟计算体素模型的5种常见摄影下受检者的器官剂量与入射体表剂量,并计算两者的转换系数,与MIRD模型所得结果进行比较。结果 体素模型得到射野内器官的转换系数分别是,胸部后前位0.149~0.650,胸部左侧位0.067~0.382,胸部右侧位0.023~0.374,腹部前后位0.035~0.431,腰椎前后位0.083~0.432。在胸部后前位下,两种模型模拟肺的剂量转换系数结果相差最大约54.3%;胸部左侧位照射的肝脏剂量转换系数差异最大为54.5%;胸部右侧位照射胃剂量转换系数差异最大为63.8%;而腹部前后位,两种模型模拟脾脏的剂量转换系数差异最大为65.0%;腰椎前后位发现胃的剂量转换系数相差最大约43.7%。结论 利用两种模型模拟得到的器官剂量转换系数偏差可达50%以上,由于MIRD模型的解剖结构过于简化,计算误差较大。利用体素模型得到的转换系数数据更加科学合理。     

三种含天然放射性布料使用所致成年男性参考人的辐射剂量评估

目的评估使用含天然放射性物质的3种布料所致人体的皮肤年当量剂量与年有效剂量。方法首先利用γ能谱仪测量3种布料样品中所含放射性核素的活度。然后利用蒙特卡罗软件建立理论照射模型,基于国际放射防护委员会(ICRP)男性参考体素模型计算器官剂量及有效剂量,从而对人体的皮肤年当量剂量和年有效剂量进行评估。结果在四周包裹和上覆盖的估算模型中,样品质量从135 g至7197 g变化范围内,这些布料所致成年男性参考人皮肤的年当量剂量范围为:155.41~9028.61μSv,一年中的有效剂量范围为:11.91~1234.44μSv。结论含放射性物质的消费品对人体会产生一些影响。     

X射线CT受检者器官剂量的研究

本文应用非均匀拟人体模和LiF(Mg,Cu, P)圆片热释光剂量探测器,测量了CT-W500(日立)全身扫描机在临床操作条件下躯干部位cT检查时的体表照射量分布,7种主要CT检查时的体表参考点照射量和17种组织或器官的剂量； 并实际调查了CT受检者平均体表参考点照射量； 计算出与体表参考点单位照射量相应的器官剂量转换系数以及与每人次cT检查相关的器官剂量和加权剂量。     

人体受照器官有效剂量当量的实验评价

本文给出了人体受照器官平均剂量当量的实验评价。实验将氧化镀(Beo)热释光剂量计布放在RANDO男性和女性体模的不同器官内, 测量前一后入射方向(anterior-posterior)不同光子能量所产生的平均器官剂量, 并根据ICRP26号报告书推荐的剂量限值体系, 估算出人体器官的有效剂量当量。同时与蒙特卡罗理论计算结果进行了比较。结果表明, 人体受照器官有效剂量当量的理论值与实验估计值具有良好的一致性。尽管还没有证实测量值的总精确度, 考虑到实验条件较为先进, 可以认为, 总测量精度不超过20%。     

不同版本国际放射防护委员会建议组织器官权重因子对心脏介入诊疗所致有效剂量的影响

目的 对比采用国际放射防护委员会(ICRP)60和ICRP 103组织器官权重因子计算冠状动脉血管造影术(CAG)及经皮穿刺腔内冠状动脉成形术(PCI)所致有效幅射剂量的变化.方法 采用在ART仿真人体辐照体模(fluke biomedical)躯干部分布放热释光剂量计的方法获得器官剂量,再将器官剂量按照不同版本ICRP组织器官权重因子加权求和获得有效剂量.分析有效剂量变化趋势及原因.同时计算有效剂量与剂量面积乘积(DAP)转换系数.结果 ICRP 103对组织器官权重因子进行调整后带来了有效剂量的增加:CAG(6.88%)和PCI(8.46%).对于CAG、PCI诊疗过程,权重因子的变化带来女性有效剂量的变化为7.25%(8.76%),男性有效剂量的变化为6.51%(8.17%);有效剂量对DAP的转换系数也从0.10(0.13)变为0.11(0.14).结论 ICRP 103对组织器官权重因子的调整导致了CAG和PCI诊疗过程所致患者器官剂量的增加,对于有效剂量增加幅度PCI略高于CAG,女性患者略高于男性患者.有效剂量的增加有两方面原因:器官权重因子变化小而器官当量剂量大和器官当量计晕小但器官权重因子变化大.有效剂量和DAP之间转换系数的变化表明在介入放射工作中用转换系数估算患者有效剂量时要考虑新版本ICRP对组织器官权重因子的调整.     

腹部透视病人体表剂量与器官吸收剂量关系的研究

本文介绍了用实验方法得出不同照射条件下的腹部透视器官典型位置皮肤剂量到吸收剂量转换系数值.典型照射条件下的转换系数(mSv/mGy)为:辜丸0.002,卵巢0.019、乳腺<0001、红骨髓0.043,肺<0.001,骨表面0.0079、甲状腺<0.001、其余组织0.012;并采用Drexler等人给出的权重因子得出了加权剂量当量转换系数.本文结果认为,在用体表受照剂量估算器官吸收剂量时,应考虑到照射条件的因素,以免高估或低估器官吸收剂量。     

Equivalent dose to organs and tissues in hysterosalpingography calculated with the FAX (Female Adult voXel) phantom

Hysterosalpingography (HSG) is a radiological examination indicated for investigating infertility or uterine and tubal pathologies. Women who undergo HSG are relatively young, typically between 20 years and 40 years, and equivalent doses to the ovaries are usually reported to be around 4 mSv per examination. A review of studies on patient dosimetry in HSG revealed that almost all absorbed doses to organs and tissues had been calculated with conversion coefficients (CCs) based on hermaphrodite versions of MIRD5-type phantoms. The CCs applied had been taken from data sets for abdominal or pelvic examinations because CCs for HSG examination were not available. This study uses the FAX (Female Adult voXel) phantom in order to calculate equivalent doses to radiosensitive organs and tissues especially for exposure conditions used in HSG. The calculations were also performed for the MIRD5-type EVA phantom to demonstrate the influence of anatomical differences on organ equivalent dose. The results show organ and tissue equivalent doses as a function of the variations of the exposure conditions. At 4.56 mSv the ovarian equivalent dose calculated for the FAX phantom is about 21% greater than the average ovarian equivalent dose reported in the literature, which reflects the anatomical differences between the FAX and the MIRD5-type phantoms.     

有效剂量与有效剂量当量的异同

本文作者主要讨论ＩＣＲＰ６０号出版物中提出的有效剂量，与ＩＣＲＰ２６号出版物中的有效剂量当量，在概念和使用上比较它们的异同。     

Relationships between physical dose quantities and patient dose in CT

Patient dose in CT is usually expressed in terms of organ dose and effective dose. The latter is used as a measure of the stochastic risk. Determination of these doses by measurements or calculations can be time-consuming. We investigated the efficacy of physical dose quantities to describe the organ dose and effective dose. For various CT examinations of the head, neck and trunk, organ doses and effective doses were determined using conversion factors. Dose free-in-air on the axis of rotation (Dair) and weighted computed tomography dose index (CTDIw) were compared with the absorbed doses of organs which are located totally within the body region examined. Dose-length product (DLP) was compared with the effective dose. The ratio of the organ dose to CTDIw was 1.37 (0.87-1.79) mSv mGy-1. DLP showed a significant correlation with the effective dose (p < 0.005). The average ratio of effective dose to DLP was 0.28 x 10(-2) mSv (mGy cm)-1 for CT of the head, 0.62 x 10(-2) mSv (mGy cm)-1 for CT of the neck and 1.90 x 10(-2) mSv (mGy cm)-1 for CT of the trunk. CTDIw and DLP can be used for estimating the organ dose and effective dose associated with CT examinations of the head, neck and trunk.     

基于体型特异性剂量估算值推算冠状动脉CT血管成像中患者器官剂量和个体有效剂量的可行性研究

目的 探讨将体型特异性剂量估算值（SSDE）用于估算冠状动脉CT血管成像（CTA）中患者器官剂量和个体有效剂量的可行性。方法 回顾性连续纳入冠状动脉CTA患者421例,均于第3代双源Force型CT采用前瞻性心电门控触发轴扫协议检查。通过Radimetrics计算患者水当量直径以计算每位患者的SSDE;使用Monte Carlo模拟估算患者扫描范围内器官的吸收剂量包括心脏、肺、肝和乳腺。使用国际放射防护委员会（ICRP）103报告的器官敏感加权系数,将患者主要敏感器官的剂量加权求和计算个体有效剂量。使用线性相关分析验证SSDE与器官剂量及个体有效剂量的相关性,并推导基于SSDE估算器官剂量和个体有效剂量的转换系数。使用平均差值比评价该估算方法的准确性。结果 容积CT剂量指数（CTDI_vol）为（16.8±8.7） mGy,SSDE为（20.8±8.8） mGy,个体有效剂量为（4.4±2.9） mSv。基于SSDE估算器官剂量的线性拟合公式为：心脏Y=1.2X-6.4（R²=0.91,P<0.05,平均误差0.1%）;乳腺Y=1.4X-7.4（R²=0.91,P<0.05,平均误差7.9%）;肺脏Y=0.89X-4.6（R²=0.86,P<0.05,平均误差8.3%）;肝脏Y=0.36X-1.8（R²=0.64,P<0.05,平均误差-17.9%）。基于SSDE估算个体有效剂量的线性拟合公式为：男Y=0.21X-1.2（R²=0.92,P<0.05,平均误差0.2%）;女Y=0.39X-2.2（R²=0.93,P<0.05,平均误差1.7%）。结论 在冠状动脉CTA检查中通过SSDE和相应的转换系数可估算被照射器官吸收剂量和个体有效剂量,将有助于在临床工作中实现患者辐射剂量及风险的个性化评估和精准管理。     

Effective dose from radiopharmaceuticals

The effective dose, as defined by the International Commission on Radiological Protection (ICRP 1991), provides a possibility of expressing the radiation risk to patients undergoing different radiodiagnostic procedures by means of a single figure. This has been obtained by introducing organ or tissue weighting factors reflecting the radiation sensitivity of the organs. Such weighting factors were first published by the ICRP in publication 26 (1977), and have now been revised in publication 60 (1991). The effective dose for almost all radiopharmaceuticals in clinical use has been recalculated using the new weighting factors from ICRP 60 (1991) and compared with results from former calculations. A slight decrease in the numerical value for the effective dose has been observed, on average 11%. However, this does not correspond to a decrease in the estimated risk from the irradiation, since this has been re-evaluated and found to be higher than earlier believed (NAS 1990; ICRP 1991). Correspondence to: L. Johansson     

Estimation of organ dose equivalents from residents of radiation-contaminated buildings with Rando phantom measurements.

Since August 1996, a dose reconstruction model has been conducted with thermoluminescent dosimeter (TLD)-embedded chains, belts and badges for external dose measurements on the residents in radiation-contaminated buildings. The TLD dosimeters, worn on the front of the torso, would not be adequate for dose measurement in cases when the radiation is anisotropic or the incident angles of radiation sources are not directed in the front-to-back direction. The shielding and attenuation by the body would result in the dose equivalent estimation being somewhat skewed. An organ dose estimation method with a Rando phantom under various exposure geometries is proposed. The conversion factors, obtained from the phantom study, may be applicable to organ dose estimations for residents in the contaminated buildings if the incident angles correspond to the phantom simulation results. There is a great demand for developing a mathematical model or Monte Carlo calculation to deal with complicated indoor layout geometry problems involving ionizing radiation. Further research should be directed toward conducting laboratory simulation by investigating the relationship between doses delivered from multiple radiation sources. It is also necessary to collaborate with experimental biological dosimetry, such as chromosome aberration analysis, fluorescence in situ hybridization (FISH) and retrospective ESR-dosimetry with teeth, applied to the residents, so that the organ dose equivalent estimations may be more reliable for radio-epidemiological studies.     

Effective dose evaluation for BNCT treatment in the epithermal neutron beam at THOR

This paper aims to evaluate the effective dose as well as equivalent doses of several organs of an adult hermaphrodite mathematical phantom according to the definition of ICRP Publication 60 for BNCT treatments of brain tumors in the epithermal neutron beam at THOR. The MCNP5 Monte Carlo code was used for the calculation of the average absorbed dose of each organ. The effective doses for a typical brain tumor treatment with a tumor treatment dose of 20 Gy-eq were evaluated to be 0.59 and 0.35 Sv for the LLAT and TOP irradiation geometries, respectively. In addition to the stochastic effect, it was found that it is also likely to produce deterministic effects, such as cataracts and depression of haematopoiesis.     

Does collimation affect patient dose in antero-posterior thoraco-lumbar spine?

IntroductionThe purpose of this study is to determine the effect of collimation on the lifetime attributable risk (LAR) of cancer incidence in all body organs (effective risk) in patients undergoing antero-posterior (AP) examinations of the spine. This is of particular importance for patients suffering from scoliosis as in their case regular repeat examinations are required and also because such patients are usually young and more susceptible to the effects of ionising radiation than are older patients.MethodsHigh sensitivity thermo-luminescent dosimeters (TLDs) were used to measure radiation dose to all organs of an adult male dosimetry phantom, positioned for an AP projection of the thoraco-lumbar spine. Exposures were made, first applying tight collimation and then subsequently with loose collimation, using the same acquisition factors. In each case, the individual TLDs were measured to determine the local absorbed dose and those representing each organ averaged to calculate organ dose.This information was then used to calculate the effective risk of cancer incidence for each decade of life from 20 to 80, and to compare the likelihood of cancer incidence when using tight and loose collimation.ResultsThe calculated figures for effective risk of cancer incidence suggest that the risk when using loose collimation compared to the use of tight collimation is over three times as high and this is the case across all age decades from 20 to 80.ConclusionTight collimation can greatly reduce radiation dose and risk of cancer incidence. However collimation in scoliotic patients can be necessarily limited.