BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE 职业卫生基本原则 Day 4 第4天

17 - IONIZING RADIATION 17-电离辐射

Nature 性质 It is possible to explain many atomic scale phenomena by assuming that all atoms are made up of three fundamental particles. These are called electrons, protons and neutrons. 通过假设所有原子均由三种基本粒子（电子、质子和中子），构成，可以解释许多原子级现象。 The simplest atomic combination is formed by one electron and one proton ‑ the hydrogen atom. 一个电子和一个质子可以构成最简单原子（氢原子）。 In general, however, a number of negatively charged electrons rotate in certain allowed orbits around a central nucleus which is composed of an equal number of positively charged protons and some neutrons. 但是，一般情况下，多个带负电电子在指定轨道上围绕中心核旋转，该中心核由相同数量的带正电电子和一些中子构成。

Hydrogen Isotopes 氢同位素 氘 氚

Different Types of Ionising Radiation 电离辐射的不同类型 Symbol 符号 Nature 性质 Charge 带电 Relative Mass 相对质量 Range in Air 空气中的范围 Penetration 渗透 alpha 阿尔法  particulate (helium nucleus) 微粒（氦核） + + 4 0.4 - 2 cm None 无 beta 贝它  (electron) 微粒（电子） - 1/1800 5-20 cm Slight 轻微 neutron 中子 n (neutron) 微粒（中子） 1 long High 高 Gamma 伽马  electro-magnetic 电磁 v.long x-ray X射线 

Radionuclides 放射性核素 A radionuclide loses its radioactivity by decay. Ionising radiation is emitted from unstable nuclei which are decaying, with the emission of energy. 电离辐射是不稳定原子核放出的射线，有能量发出，原子核会衰变。 These are known as radioactive nuclei (radionuclides). 这些就是放射性核（放射性核素）。 The trefoil symbol is used to indicate radioactive material. 表示放射性物质的三叶形符号。 A radionuclide loses its radioactivity by decay. 放射性核素通过衰变失去放射能。

Units of Ionising Radiation 电离辐射的单位 Most countries now use the International System of Units (abbreviated SI from the French le Système International d'Unités) which is the modern form of the metric system. 现在，大多数国家采用国际单位制（简称SI，来源于法国国际单位制）来表示电离辐射的单位，该单位是现代公制形式。 The US continues to use an older system for some regulatory purposes. 因监管原因，美国继续沿用老版单位制。

Units for Measuring Radiation – Part 1 辐射测量单位 - 第1部分 Activity (Becquerel) 活度（贝克勒尔） The SI unit of for the activity of a radioactive material is the becquerel (Bq), where one Becquerel = 1 disintegration per second. 度量放射性材料活性的国际标准单位是贝克勒尔(Bq)，1贝克= 1次核衰变/秒。 The traditional unit of activity has been the Curie (Ci), where one Curie = 3.7 x 1010 disintegration's per second. 活度旧单位是居里(Ci)，1居里= 3.7 x 1010次核衰变/秒。

Units for Measuring Radiation – Part 2 辐射测量单位 - 第2部分 Absorbed Dose (Gray) 吸收剂量（戈瑞） This is a measurement of the energy imparted to matter by ionising radiation per unit mass of the material. The SI unit of absorbed dose is the gray (Gy), which is equal to an energy absorption of 1 joule/Kg. 吸收剂量是指单位质量物质接收电离辐射的能量。吸收剂量的SI单位是戈瑞（Gy），等于1焦耳每千克。 The traditional unit of absorbed dose is the rad, where 1 Gray = 100 rads. 吸收剂量旧单位是拉德(rad)，1戈瑞= 100拉德。

Units for Measuring Radiation – Part 3 辐射测量单位 - 第3部分 Dose Equivalent (Sievert) 当量剂量（西韦特） Equal absorbed doses may not always give rise to equal risks of any biological effect. The relative biological effectiveness of a particular absorbed dose may be affected by the type of radiation or the radiation conditions. Accordingly the equivalent dose can be expressed as: 相同的吸收剂量不一定会产生相同的生物效应风险。特定吸收剂量的相对生物有效性受辐射类型或辐射条件的影响。因此，当量剂量可以采用如下公式来表达： Dose equivalent (Sievert) = Absorbed dose (Gray) x Modifying Factor. 当量剂量（西韦特）=吸收剂量（戈瑞）*修正因子。 The modifying factor depends on both the 'quality' of the radiation (which is 1.0 for the lower energy radiations but rises to 20 for high energy fission fragments) and the part of the body affected. 修正因子取决于辐射质量（低能量辐射为1.0，高能量裂变碎片为20）和受影响的部位。 The traditional unit is the rem where 1 sievert = 100 rem. 当量剂量旧单位是雷姆，1西韦特= 100雷姆。

External Radiation 体外辐射 The effects of external exposure can be summarised as: 体外辐射的影响可以归为：  Minimal hazard  最小危害  Skin and eyes at risk  对皮肤和眼睛有危害  Whole body at risk (penetrating radiation)  全身都有危害（贯穿辐射）

Internal Radiation 体内辐射 The internal effects of exposure are: 体内辐射的影响可以归为：  Very serious hazard  非常严重的危害  Serious hazard  严重危害  Not normally applicable  一般不适用

Levels of Radiation 辐射等级 The Los Alamos National Laboratory in the US provides an online tool which enables you to calculate your annual radiation dose. This takes into account: 美国洛斯阿拉莫斯国家实验室提供了计算年辐射剂量的在线工具，该工具中列入的相关因素包括： Cosmic radiation which increases with height above sea level 宇宙辐射，海拔越高，辐射越大。 The material which your home is made from. 居家建材 Time spent on aircraft 飞行时间 Smoking 抽烟 Medical x–rays 医用X-射线 Other lifestyle factors. 其他生活方式因素。

Biological Effects of Ionising Radiation 电离辐射的生物作用 Acute Effects 急性作用 Chronic Effects 慢性作用 Erythema 红斑 Cancer 癌症 Blood change 血液改变 Hereditary defects 遗传性缺陷 Sterility 不孕不育 Death 死亡

Uses of Radiation – Part 1 辐射的利用——第1部分 Industrial 工业 Gauges - radiation (, , , neutrons) can be used to measure thickness, density and moisture level 辐射计——辐射(、、、中子)可用于测量厚度、密度和湿度等级。 Industrial Radiography - checking the integrity of welds (, ) 工业放射摄影术——检查焊缝的完整性(, ) Laboratory analytical techniques - X-ray diffraction and fluorescence 实验室分析技术——X射线衍射和辐射荧光 Tracers - Radionuclides are used in yield determination, wear tests, water and oil reservoir investigations. 示踪剂——放射性核素可用于产额测定、磨损试验、水箱和油箱检查。

Uses of Radiation – Part 1 辐射的利用——第1部分 Medical 医疗 Diagnostic X-rays 诊断X射线 Medical imaging - radionuclides are sometimes used as markers. 医学影像——放射性核素有时可用于进行标记。 Cancer treatment - using radionuclides to destroy tumours. 癌症治疗——使用放射性核素杀死肿瘤。

Measurement of Radiation – Part 1 辐射的测量 - 第1部分 Emitted radiation: Geiger counters and scintillation counters can be used to measure the levels of radiation from particular sources. The devices are often specific to the type of radiation being measured. 发射辐射：可使用盖革计数器和闪烁计数器来测量特定辐射源的辐射等级。通常应根据辐射类型来确定选用的设备。

Measurement of Radiation – Part 2 辐射的测量 - 第2部分 Radiation dose: Various devices can be used to measure personal dose. It is important to differentiate between internal dose (that which a person takes into their body by routes such as breathing) and external dose (received simply by virtue of being in an environment where radiation is present). 辐射剂量：有各种设备都可以用来测量个人剂量。但关键是区分内辐射剂量（通过呼吸等途径进入体内的辐射）和外辐射剂量（在有辐射的环境中就会受到辐射）。

Radiological Protection – Part 1 辐射防护 - 第1部分 Time: Limiting or minimizing the amount of time to which people are exposed to radiation will reduce the dose which they receive. 时间：尽量减少接受辐照的时间，以此减少辐射 剂量。 Distance: Radiation intensity decreases sharply with distance, according to an inverse square law. In addition even air attenuates alpha and beta radiation. 距离：根据平方反比定律，距离越短，辐射强度 越小。 此外，空气也会削弱α和β辐射。

Radiological Protection – Part 2 辐射防护 - 第2部分 Shielding: Alpha particles may be completely stopped by a sheet of paper, beta particles by aluminum shielding. Gamma rays can only be reduced by much more substantial barriers. Barriers composed of lead, concrete or water give effective protection from energetic particles such as gamma rays and neutrons. Some radioactive materials are stored or handled underwater or by remote control in rooms constructed of thick concrete or lined with lead. 屏蔽：采用纸张即可屏蔽α粒子、采用铝制屏障即可屏蔽β粒子。采用大量实质障碍才可屏蔽伽玛射线。如实质障碍物中包括铅、混凝土或水，即可品屏蔽高能粒子，如伽玛射线和中子等。某些放射性物质需要在水下存储或处理，或通过厚混凝土或内衬铅建造的控制室来进行远程控制。

Radiological Protection – Part 3 辐射防护 - 第3部分 Containment: Radioactive materials may be used in "sealed sources" to prevent them spreading. The use of small working spaces, segregated areas and controlled ventilation are also used to contain the release of radioactive materials 抑制：可采用“密封放射源”方式来使用放射性材料，以避免其扩散。可使用小型工作区、隔离区和控制通风等方式来释放放射性物质。

Radiological Protection 辐射防护

Health Surveillance 健康监护 Employees working in controlled areas would typically be subjected to: 控制区内工作的员工通常需要进行： Completion of a questionaire 完成问卷调查 A blood test 验血 Urine test 尿检 Blood Pressure check 血压检查 Height and Weight Check 身高和体重检查 General discussion about health. 常规健康问题回答