放射防护学课件：Chapter 3 Radiation exposure in human life

1、Chapter 3 Radiation exposure in human life 第三章、 人类生活中所受到放射性照射Contents: 1 external exposure from naturally-occurring background radiation to human2 internal exposure from naturally-occurring background radiation to human3 yearly effective dose contributed by natural radioactive source to human4 the n

2、atural radiation caused by human activities5 controlling natural radiation6 the exposure of artificial radioactive sourceRadiation dose in lifeRadiation is an essential part of our life-from birth, we are exposed to radiation from cosmic rays in our surroundings -from food and drink that may contain

3、 traces of radioactivity. -human body contains small amounts of radioactivity (in the form of radioisotopes of potassium, caesium and radium). -The typical adult body emits about 24,000 gamma rays per minute, a very tiny amount of radiation. Not only is radiation an essential part of human life, it

4、can also be used to improve human life.-the role of health care providers to use ionizing radiation in medicine efficiently so as to maximize benefit and minimize risk. -The International Atomic Energy Agency (IAEA) continuously works towards making radiation use safer.-However, potential benefits f

5、rom radiation use come with a risk as many other benefits of human life do. -The important thing is keeping the benefits overwhelming the risks.What are the sources of radiation exposure?Naturally radiation exposure falls into two main categories: -natural sources（天然放射源）: -cosmic ray （宇宙射线）: -terres

6、trial origin（地球辐射）: Radiation also comes from the earth itself, such as rocks and soil and naturally occurring isotopes emitting radiation These sources can impart doses to human tissues by external irradiation, inhalation (mainly radon gas inside buildings) or ingestion (mainly 40K). The average ra

7、diation dose from all natural sources is around 2.4 mSv per year (as a global average) and corresponds to slightly less than 80% of the total average dose received by humans -Artificial (man-made) sources(人工放射源) -Medical radiation （医疗照射） use being responsible for just under 20% of the total average

8、dose. -The remaining 0.40% consists of dose contributions from nuclear weapons testing fall-out, occupational exposure, nuclear power plant discharges and radiation from the Chernobyl accident. All contributions to the average annual dose according to the UNSCEAR report of 2008. 天然辐射源的照射exposure fro

9、m natural sources -Cosmic rays (宇宙射线) are very high-energy particles, mainly originating outside the solar system. cosmic radiation bombarding the earth all the time. it consists of high energy particles (heavy nuclei 0.6%, alpha particles 11.2%, protons 86.2% and electrons 2%) 一、External radiation

10、from natural background on the human body - primary cosmic rays (初级宇宙射线) Cosmic rays originate as primary cosmic rays, which are those originally produced in various astrophysical processes. Primary cosmic rays are composed primarily of protons and alpha particles (99%), with a small amount of heavi

11、er nuclei (1%) and an extremely minute proportion of positrons and antiprotons.primary cosmic rays include primary galactic cosmic rays (初级银河宇宙辐射, energy is 1081020eV）and primary solar cosmic radiation(初级太阳宇宙辐射, the energy is 100eV ）Radiation belt（辐射带）: the high radiation area is formed that earths

12、magnetic field capture high-energy charged particles of the many cosmic raysHuman because of the protection by the atmosphere, ionosphere and magnetosphere, human would not have the direct effects of primary cosmic radiation. Entering space or high-altitude traveling may have direct action of cosmic

13、 radiation.-Secondary cosmic rays（次级宇宙射线） It was formed by a decay of primary cosmic rays as they impact an atmosphere, include neutrons, pions, positrons, and muons. Of these four, the latter three were first detected in cosmic rays.The effective dose of cosmic radiation on the human body The prima

14、ry cosmic rays cannot form direct radiation on the human body. Secondary cosmic ray irradiation on human body can form.Factors influencing cosmic ray intensity:height above sea level geomagnetic latitudebuilding shieldingHuman exposure levels induced by cosmic ray:Report of Committee on atomic radia

15、tion effect of the United nations:The population of the world in 2000year due to external irradiation-induced by cosmic ray : 0.4mSv/ average annual dose, the typical range 0.3-1.0mSvExternal radiation caused by ionization components in cosmic ray of lower atmosphere: 0.26mSv/annual effective dose,

16、the typical range 0.20-1.09mSvExternal radiation caused by neutron component of cosmic ray in our country in the lower atmosphere: 0.057mSv/annual effective dose-terrestrial origin (terrestrial radiation, 地球辐射): Radiation also comes from the earth itself, such as air, water, rocks and soil and organ

17、ic matter naturally occurring radiation from isotopes (radionuclide) emitting alpha particles, beta particles, a gamma nuclear decayRadionuclide divided into two parts: primordial radionuclides(原生放射性核素) cosmogenic radionuclide(宇生放射性核素)Primordial Nuclides(原生放射性核素) definition:also known as primordial

18、isotopes, they are nuclides found on the earth that have existed in their current form since before earth was formed, Many natural radionuclides, that its half-life is the similar to age of earth, widely exist in earth material, these radionuclides are called primordial radionuclides.2. components o

19、f Primordial radionuclides -Radionuclide with decay: uranium family (铀系, 238U) thorium family (钍系, 232Th） actinium family(锕系 235U） -Radionuclide without decay 40-Fission products generated by spontaneous fission (low probability, rarely) 3、 Radiation mechanism and method of primordial radionuclide f

20、ormation: direct exposure: 、 external exposure； inhalation exposure 、 internal exposure digestive exposure External exposure generated by primordial radionuclide (1)、radiation origin in environment (环境中辐射来源)：-Primordial radionuclide exists in which the earth crust. Because U, Th, K and other radionu

21、clides are easy to formoxides, they are easy to exist with silicon oxides together,and the place with much of SiO2 will have more primordialradionuclides. In addition, the soil is formed by the weathering of rocks,dose in soils is determined by formed soil rock types.(2)、 The dose contribution of ro

22、ck:Igneous rocks (火成岩)：Granite(花岗岩)（higher content with 40、226Ra和238）、 Diorite(闪绿岩)、Xuan Wuyan(玄武岩) and peridotite(橄榄岩)Sedimentary rocks(沉积岩)：limestone (石灰岩)、carbonate rock(碳酸岩)、sandstone(砂岩) and shale(页岩, * higher concentration of radioactivity)Phosphate rock (磷酸岩, radioactive concentration is high

23、)High background area (高本底地区): refers to absorbed dose rate of terrestrial gamma radiation in certain area is 3-5 times higher than that of level in most of local region, such as Yangjiang, Guangdong (广东阳江)（3）China continental high background radiation area 中国大陆高本底辐射区Yangjiang County, Guangdong: the

24、 U, Th, Ra content in soil surface containing monazite mineral was 3 times higher than in normal area (absorbed dose averaged 370nGy.h-1)More than 95% people in the world live in normal regionhigh background radiation area高本底地区-The average absorbed dose rates in air at 1m above the ground in some co

25、untries and areas (nGy.h-1):Austria 50 India 36 Poland 58 Italy 72 Switzerland 74 USA 45 East Germany 91 Japan 41 Chinese Taiwan 60-Kerala and Tamil Nadu in southwest India ca. 250Km width of 0.5Km region rich in solitary stone deposit (8-10.5% of Th-232 in the stone), live 70，000 people, this area

26、is the worlds thorium containing the highest area, average dose of air rate 1300nGy.h-1.（4）Outdoor gamma radiation:A large part of external irradiation to human body is caused by soil, sand and stones surface emitting gamma rays,Outdoor gamma radiation is mainly determined by K-40, Th-232 and U-238

27、exist in the thickness of approximately 30cm of the surface soilOutdoor gamma radiation dose is an important part of natural radiation from the radium series nuclides to human, which accounts for about 1/4 of natural radiation in normal areaabsorbed dose rate in air generated by gamma radiation - 59

28、 nGy H-1, fluctuations in the range of 18 - 93nGy / h （5）、indoor radiation(室内辐射)external exposure from building materials 来自建筑材料的外照射shielding effect of building materials 建筑材料的屏蔽作用 The report from UNSCEAR in 2000：population weighted average of radiation dose indoor terrestrial gamma-84nGy/hRange :20

29、-200nGy/h。 The Maxima in China, Malaysia etc.The Minimum in Newland, Iceland, US.建筑材料室内辐射剂量率见表3-2（6）、The average annual effective dose of external irradiation indoor, terrestrial gamma radiation produced(室内、外陆地 辐射产生的外照射平均年有效剂量) Indoor：84 nGyh-18760ha0.80.7Sv/Gy = 410 Sv terrestrial：59 nGyh-18760ha0.

30、20.7Sv/Gy =70 Sv Total： 410 Sv + 70 Sv = 480 Sv Cosmogenic radionuclide (宇生放射性核素): It was produced by different nuclear reaction of cosmic rays in the atmosphere, biosphere(生物圈)and lithosphere(岩石圈).Cosmogenic radionuclide main components: 3H、7Be、14C、22Na。The annual effective dose of cosmogenic radio

31、nuclides on the human body(宇生放射性核素对人体产生的年有效剂量) 3H 0.01 Sv 7Be 0.03 Sv 14C 12 Sv 22Na 0.15 Sv Total：12.19 Sv二、internal radiation from natural background on human body天然本底对人体的内照射-Internal exposure is caused by radionuclide entering the human body through the ingestion and inhalation,-Irradiation is ma

32、inly caused by the primordial radionuclides.-internal irradiation dose caused by cosmogenic radionuclide is little-primordial radionuclides have big irradiation effect on the human body: 40K, 238U family and 232Th family, radon and its progeny.Primordial radionuclide having greater impact of interna

33、l irradiation on the human body(对人体内照射影响较大的原生放射性核素) 1） Potassium-40(钾-40)-Potassium-40 in the body of animals and plants, which is main radiation source to cause internal radiation dose in human body through ingestion pathway. -In the natural potassium, K-40 natural abundance of 1.17*10-4, its speci

34、fic activity is low but it is as isotopes of biological elements existing in the body largely, and it is a longer half-life (1.28*109 year）, it becomes the main source of human internal exposure. -Potassium-40 emitting beta, gamma radiation, which accounted for 89.33% of beta decay.For the adult, bo

35、dy potassium-40 average effective dose of 165 Sv/aFor children and infants, it was 185 Sv/aFor residents in China, the average annual effective dose irradiation caused by the K-40 was 179 Sv/a2) uranium-238 (is divided into five sub Series) U-238 (through the food chain into the body)Th-230 (low abs

36、orption in the gastrointestinal tract);Ra-226; Ra-222 (releasing alpha particle energy account for 45% of total uranium-238 family, which is an important part for internal source)Pb-2103） Th-232 system (divided into three sub series) -Th-232 (through the food chain into the body, but in the gastroin

37、testinal absorption of low) -Ra-228-Rn-220radionuclide inhalation come from re-suspension of dirt, dust particlesThorium via the gastrointestinal absorption rate is very low, so Th-232 into the body by ingestion can be neglected. But mainly through the suction intake. Th-232 inhalation annual intake

38、 via 0.01Bq.Thorium is dear bone radionuclide; the retention in bone for long time; in the surface of the bone and lymph node with the highest specific activity, followed by the bone, lung, kidney, liver and spleen. Since bone mass is much larger than lymph node, thorium 70% in bone in vivo.Typical

39、activity of thorium-232 in bone is the 140mBq. 4）Radium-a-Radium is a decay product of uranium and thorium,-isotope of Ra has as many as 25, but as a natural source of radium isotopes to produce meaningful irradiation in human body are: 226Ra, 228Ra, 224Ra.Radium is easier to transfer to plant and a

40、nimal than thorium；Radium in the human body is mainly due to food intake, 226Ra and 228Ra in normal food intake is about 15Bq /A.不同年龄人食入原生核素的活度和待积有效剂量见表3-3Internal exposure to radon and its daughter progeny(1) Human understanding of the radon hazards-it is the one of 19 carcinogens released by WHO,

41、which is another important factors for human body to have natural irradiation，especially air accumulation in indoor .-Natural radioactive isotopes of radon nature: Rn-222 uranium series (3.82d), Rn-220 (55s) thorium series， Rn-219 actinide (3.9s), -present in solids containing the parent (such as in

42、 rock, soil, all kinds of building materials); -radon daughter refers to its progeny after radon decay.-The indoor radon and its daughter mainly come from the housing base soil, building materials, outdoor air, water, fuel. UNSCEAR gives the indoor radon concentration range of standard (table 3-4, 3

43、-5) (2) nuclide decay： 238 U 226 Ra 222 Rn （3.82d） 232 Th 224 Ra 220 Rn 235 U 223 Ra 219 RnRn-222 uranium series is the important composition of natural radioactive in the lower troposphere, which has health significance.(3) characteristics of radon: colorless, tasteless, soluble in water, soluble i

44、n water with temperature change.a0.1057+0.405exp(-0.0502t) T is temperatureUnit is degree(4) Radon-half life and healthy significance (氡的半衰期及卫生学意义) 222 Rn half-life: 3.82d There are health significance 220 Rn half-life: 55.6s There are no health significance 219 Rn half-life: 3.05s There are no heal

45、th significance(5) the mechanism of lung cancer induced by radon and its progeny氡及其子体的致肺癌作用机理 Generally considered: carcinogenesis of lung bronchial epithelial cells come from the change of nucleus in basal cells. The basal cells were spindle and localizes in the roots of the columnar cells and gobl

46、et cells, the central of the cell is the basal cell nuclei. When the thickness of bronchial epithelial cells with cilia and mucus is equal to alpha particle range, basal cell nuclei will injury by action of ionizing radiation generated by alpha particle, and further develop to cancer. (6) the main o

47、rigin, dose level of radon having effect on body and its influencing factors-origin Outdoor: soil, rock Interior: soil, water, building materials-dose level Outdoor: 10Bq/m3 Interior: 40 Bq/m3-influencing factors Outdoor: rock soil exhalation rate, temperature, humidity, wind Interior: building mate

48、rials, floor, ventilation(7) radon measurement units and special measurement-the concentration of 222Rn or 220Rn measurement in the air the unit of radioactivity concentration, Bq/m3;-222Rn or 220Rn progeny measurements in air. The used units are the following; Potential alpha energy concentration (

49、PAEC, 潜能浓度) The level of work (WL, 工作水平) Equilibrium equivalent concentration of radon (EEC， 平衡当量氡浓度)(8) The average annual effective dose of radon on the human body factors affecting radon to generate annual average effective dose on the human body-Radioactive aerosol: particle size distribution;-t

50、he ratio of alpha potential energy for not bound daughters in total alpha potential energy;-Respiratory rate;-Bronchial epithelial cell surface mucus to throat direction clearance rate -target cell thickness;-The concentration of radon and its progeny. The average annual effective dose (产生的年平均有效剂量)

51、In Air: 222Rn and its progeny 220Rn and its progenyA bronchial tube indoor: 1.0 mSV 0.084 mSV outdoor： 0.095 mSV 0.007 mSV blood indoor： 0.048 mSV 0.008 mSV outdoor: 0.003 mSV 0.002 mSV total： 1.146 mSV 0.101 mSV222Rn and its progeny in water: inhalation：0.025 mSV digestive：0.002 mSV 三、The annual ef

52、fective dose of natural sources of radiation on the human body(天然辐射源对人体产生的年有效剂量_四、 the natural radiation caused by human activities(人为活动变更的天然辐射)Refers to the natural radiation caused by some human activities with non-specifically designed for production of radiation（一）Natural radioactive material im

53、provement (天然放射性物质的提升)Mining and geothermal energy production is the main way:-Uranium, thorium mining and smelting and nuclear energy is closely related to the development, belongs to the radioactive workplace;-Rare earth mining and smelting, phosphate ore, part of non-ferrous metal mining with rad

54、ioactive operation;-Phosphate rock is a major source of phosphorus, uranium content in the phosphate minerals is higher;High temperature rock of the deep earth with hot steam or hot water is one of the available for people to use energy, geothermal fluid containing radioactive nuclide Rn-222, can es

55、cape into the air.（二）Concentration of natural radioactive substances(天然放射性物质的浓集)-Such as the burning of coal, resources utilization, human food and drinking water.-Coal contains trace amounts of natural primordial radionuclides, coal combustion caused these radionuclides released into the environmen

56、t, and the re-distribution of radionuclide-Petroleum, natural gas will be discharged radionuclides in underground-Application of phosphate fertilizer and rare earth fertilizer, increase the content of radionuclides in soil-The construction of the reservoir, the radioactive background high region if

57、the river from upstream, it will increase the radioactive contents of water flow and sediment deposition, also.-Radioactive substances often contain mineral water and hot springs, such as Ra-226, Rn-222-Animal enrichment of some natural radionuclides, such as shrimp, shellfish, fish production.（三） i

58、ncreased irradiation (受照增加)-natural radioactivity transferred to the ground mining, natural radioactivity enrichment area, high background area can made the residents to have higher irradiation.-Artificial radioactivity:improper selection of building material: residue pad with uranium; stone walls c

59、ontaining high radioactivity; stone coal cinder brick building; strong radioactive materials (granite) for room decoration; air conditioning indoor ventilation;-High-altitude flight, the crew at 10km high altitude for long timeflight will have strong irradiation of cosmic ray.飞行航线普通喷气飞机超音速飞机飞行时间h剂量S

60、v飞行时间H剂量Sv洛杉矶-巴黎芝加哥-巴黎纽约-巴黎纽约-伦敦北京-上海北京-广州北京哈尔滨北京-昆明北京-拉萨北京-乌鲁木齐11.18.37.47.02.53.52.54.04.54.54836312910.815.110.817.219.419.438282624 37 26 24 22 表1.3.飞机乘客所接受的宇宙射线剂量Cosmic ray dose at an altitude of 10000 meters to passengers is accepted about 5 Sv per hour. 在1万米高空乘客每小时所接受的宇宙射线剂量约为5Sv 五. controlli