放射物理学英文版课件完整版.ppt

, ,BME College Sherman sheen,Why we study this subject?,Diagnostic radiology放射诊断学 Radiotherapy放射疗法 Radiobiology放射生物学 Nuclear medicine 核医疗学,Diagnostic radiology放射诊断学,CT scanner; CT扫描 X-ray machine;爱克斯光机 DR; C-arms; PET;Performance Evaluation Test 性能鉴定试验 radiological imaging放射影像学,CT SCANNER,PET,Radiotherapy放射疗法,traditional methods to kill tumors治疗肿瘤的传统方法 clinical physicist;临床物理学家，医学物理师 TPS;Technical Problem Summary 技术问题摘要,Radiobiology放射生物学,the interaction between the radioactive particles and the cells 在放射性的粒子和细胞之间的交互作用 research work to make the radiology more advantageous for human研究工作让 X 光线学变得更有利于人类,Nuclear medicine核医疗学,ECT, 电休克治疗 SPECT;单光子发射计算机化断层显像 very popular abroad; bright future;,Basic Concepts,Quantities and units量和单位 (physical quantity)=(numerical value)*(some unit) International system of units (SI)单位的国际系统 Fundamental Units基本的单位 Q: review the fundamental units? mass length time current,Basic Concepts,Basic Concepts,Derived units导出单位 velocity 速度 ratio 比率of the increment增长 of distance to time acceleration 加速度 ratio of the change of velocity to time force (newton)力（牛顿） related to acceleration defined 界定by Newtons law of motion 运动定律,运动定律,Basic Concepts,Derived units导出单位 work or energy (joule焦耳 ) W=F*l power (watt),功率 rate of doing work frequency 频率(hertz赫兹) number of oscillation per unit time单位时间振动次数,Example 1-1. A young scientist of mass 75 kg at the Ontario Cancer Institute, in a foolish trial of endurance, ran from the basement to the seventh floor (height 25.8 m) in 23.6 s（在 23.6 秒中从地下室跑到七楼（高度 25.8 m） .Calculate the work done and the power developed . In Toronto the acceleration due to gravity is 9.8 ms-2 .课本P4,Basic Concepts,Electrical units电单位 charge (coulomb)电荷(库仑) 1 coulomb = 1 C = 1 ampere second = 1 A s potential difference (volt)位差,电势差(伏特) Potential difference = Electrical circuits电路,Work done = Q V = I t V,Basic Concepts,Electrical units capacity（电容）: ability to store charge resistance（电阻）,Example 1-2 . A potential of 12 volts placed across a heating coil暖管 produces a current of 1.5 amperes. Find the resistance （电阻）of the coil, the charge which passes through the coil in 1.0 min, the energy dissipated（消耗的能量）, and power 功率developed.,Example 1-3. A current of 2.5 10-6A flows into a 20.0 10-6 F condenser电容器 for 20 seconds. Find the potential （电势差）to which the condenser is charged.,Basic Concepts,Radiation units辐射单位 absorbed dose吸收剂量 energy deposited吸收 by ionizing （电离）radiation per unit mass of material 1 Gy = 100rads = 1J/kg exposure 曝光 the charge（电荷 ）liberated（释放） by ionizing radiation ( output of an X ray generator发生器) per unit mass of air 1 roentgen （伦琴）= 2.58*10-4 C kg -1,Basic Concepts,Radiation units activity 活性 the number of disintegration（裂变） per unit time of a radioactive isotope （放射性同位素） unit: becquerel 贝可勒尔(放射性强度单位, 每秒有一个原子衰变) 1Bq = 1s-1 1Ci = 3.70*1010 Bq,Summary,The physics of radiology（X 光线学的物理学 Fundamental units基本的单位 Derived units导出单位 Units used in radioactive field（放射领域）, , TWO,BME College Sherman sheen,Atoms原子,Matter is composed by atoms物质由原子组成 Structure of Atoms nucleus(原子)核-radius半径 10-14m electrons clouds-radii 半径10-10m Atomic number原子序数: Z number of electrons chemical properties化学特性,Constitution结构，构造 protons (质子) neutrons(中子) Q: How to know the structure of the nucleus? Q: Properties of protons and neutrons: charge and mass mass number(原子)质量数: A protons + neutrons neutrons = A-Z,Nucleus原子核,nucleon核子,Isotope同位素 definition(定义): Atoms composed of nuclei 原子核(nucleus的复数形)with the same number of protons (质子)but different number of neutrons(中子) are called isotopes. stable 稳定的or unstable ; disintegration（裂变） and radioactive; （ 放射性的）,Nucleus原子核,Atomic Mass原子质量,Carbon 碳 mass number 原子序数12 represented by A【mass number(原子)质量数】 Notation for atomic species原子种类的标记法 subscripts（下标）-Z and superscripts（上标）-A Isotope of Hydrogen氢, Helium氦, Cobalt钴(符号为Co),Elemental particles基本粒子,pproton 1.007277, +1 The proton is the nucleus of the hydrogen atom. The hydrogen atom consists of 1 proton in the nucleus and 1 external（外部的） electron. The mass of the neutral atom （中性原子）is 1.007277 +0.000548 = 1.007825 mass units. The proton is one of the fundamental building blocks of all nuclei. Beams（束, 柱） of protons are being used in radiotherapy.（放射疗法）,Elemental particles基本粒子,nneutron 1.008665, 0 The neutron(中子) is the other fundamental building block of all nuclei. Neutrons have nearly the same mass as protons. Since the neutrons is an uncharged particle （不带电粒子）it is hard to stop and difficult to detect（查明，发现，发觉. ）Beams of neutrons are being used in radiotherapy.,Elemental particles基本粒子,e- - 0.000548, -1,The electron has a very small mass compared with the proton. Electrons abound in nature. Every atom contains electrons outside the nucleus. The electron is easily detected. It is sometimes called a negatron（阴电子 ）or beta particle（粒子） and represented by e, e- or -.Beams of high energy electrons are extensively（广泛地） used in radiotherapy.,Elemental particles基本粒子,e+ + 0.000548, +1,The positron（正电子） has the same mass as an electron but carries a positive charge. Positrons exist in nature only while they are in motion（在运转中;处于兴奋状态）. A slowly moving or stationary(静止的) positron quickly combines with an electron to form a burst (爆炸, 爆裂)of radiation in the form of （用的形式）two gamma rays（射线） (see below). Positrons are represented by e+, or + and referred to as beta plus particles They are used in nuclear medicine（核医疗学）.,Elemental particles基本粒子,Hv , 0, 0,Strictly speaking, the photon （光子）is not a particle, but a bundle一捆 of energy which travels at the speed of light (3108ms-1). In many interactions（相互作用） it acts much like a particle. Photons are referred to almost interchangeably（可替换地） as quanta 量子(quantum的复数形式)or gamma rays and are represented symbolically（象征性地） by h or . Beams of photons account for the major part of external beam （外粒子束;外束）radiotherapy（放射疗法）.,Elemental particles基本粒子,neutrino 中微子e , 0,The neutrino （中微子）is a very small particle with practically （几乎）no mass and no charge. For this reason, it has been very difficult to detect experimentally（根据实验地）. Its interaction （相互作用） with protons to form neutrons and positrons according to the reaction（反应）e+ p n + + has been observed. The neutrino was introduced originally from theoretical （假设的，理论的）considerations to help explain beta decay（衰变）.,Elemental particles基本粒子,Mu mesons（介子） , + , - , 207m0 ,+1 or -1,Mu mesons may be either positively or negatively charged （带负电荷的）and have a mass 207 times the mass of the electron. They are produced indirectly（间接地） by the interaction of very high energy particles with matter（物质,物体）. The particles are unstable and decay spontaneously （自发地衰变）into electrons and neutrinos（中微子 according to the reactions + e+ + 2 - e- + 2 The mean life（平均寿命） of the particles is 2.1510-6 sec.,Elemental particles基本粒子,Pi mesons （介子） , + 273 m0 +1 - 273 m0 -1 0 265 m0 0,Pi mesons may have a positive a negative charge or may be neutral（中性的）. They are produced by the bombardment （炮击；轰炸）of matter with high energy protons or photons. The charged mesons decay into mu mesons and neutrinos（中微子） according to + + + - - + with a mean life of 2.510-8 s. The neutral 0 meson decays（衰变） into 2 photons 0 h1 + h2 with a mean life of 10-15 seconds. Beams of negative mesons are being used in radiotherapy（放射疗法）.,Elemental particles（放射疗法）,pproton 1.007277, +1 nneutron 1.008665, 0,e- - 0.000548, -1,e+ + 0.000548, +1,H 0, 0,e , 0,Mu mesons 207m0 ,+1 or -1 Pi mesons 273m0 ,+1 or -1 265m0 0,Extranuclear structure核外的结构,Arrangement of planetary electrons 行星式电子 outside the nucleus,The outermost orbit最外层轨道 Chemical properties and valence(化合)价 repeat inert gas惰性气体 : He, Ne, alkaline elements碱性元素: lithium锂, sodium钠,Extranuclear structure行星式电子 chemical properties化学特性,Atomic Energy levels原子能级,Optical radiation 光辐射and X radiation,Nuclear Energy levels核能级,Gamma ray（伽马射线,射线）,伽马射线,射线,Quantum nature（量子种类，性质） of radiation,Quantum (量子)or Photon（光子） bundle of energy 能量束 Energy of a Photon,For a diagnostic （诊断的）X-ray Generator（发生器）, wavelength （波长）10pm, 1 photon:,Quantum nature of radiation,Important equation方程式, 等式,Wavelength （波长） and energy,Quantum nature and continuous radiation连续辐射,Electromagnetic Spectrum 电磁波频谱,Electromagnetic Spectrum电磁波频谱,Electromagnetic Spectrum电磁波频谱,Electromagnetic Spectrum电磁波频谱,Electromagnetic Spectrum,Electromagnetic Spectrum,Electromagnetic Spectrum,Electromagnetic Spectrum,Binding energy结合能 K radiation, BE: 70000ev L radiation, BE: 11000ev M radiation, BE: 2500ev,Radiation of energy （能量辐射） from an atom,Radiation of energy from an atom,summary,Atoms原子 The Nucleus原子核 Elemental Particles基本粒子 Extranuclear Structures核外结构 Atomic Energy Levels原子能级 Nuclear Energy Levels核能级 Electromagnetic Radiation电磁辐射 Quantum Nature of Radiation The Electromagnetic Spectrum电磁波频谱 Radiation of Energy from an Atom 原子的能量辐射, , Three,BME College Sherman sheen,Mass and energy质量和能量，质能,Einsteins theory E = m c2 C代表光速,Energy corresponding to one electron能量相当于,1 kg m2S-2 = 1 joule,Because:,Mass and energy质能,mass of one carbon atom =,Example 1-7. Calculate the energy equivalent(能当量) of 1 atomic mass unit (amu).,Avogadros number(阿伏伽德罗数 )= 6.022045 1023,carbon has a mass number【(原子)质量数】 of 12, it contains 12 amu Hence, the conversion （ 转化）of 1 amu to energy,two important mass-to-energy conversion factors 转换因数:,Mass and velocity,m0 , the rest mass静止质量,1/10 the velocity of light , increase in mass of 0.5% 98% of light (v/c0.98), 5 times of the rest mass,Mass and velocity,Exponential behavior指数式变化,the rate of change of a function（函数） is proportional （比例的, 成比例的）to the function.,If a quantity changes by a certain factor （一个特定的因素）in a given interval of time（时间间隔）, then there will be exponential behavior if in any other equal interval of time （相等时间间隔）it changes by the same factor 相同的因素,Exponential behavior指数式变化,the growth of money in a bank account银行存款, the growth of populations, the growth of cells, the decay（衰变） of radioactive isotopes（放射性同位素） the killing of cells by radiation, the attenuation （变细；变薄;减弱）of x ray beams,Occurred（发生） while:,EXPONENTIAL DECAY（指数式衰减） OF A RADIOACTIVE ISOTOPEHALF-LIFE（半衰期）,on the average, after the half-life, half the radioactive atoms（放射性原子） will disintegrate（破裂分裂）. In the next half-life, one-half of the remaining （剩下的）atoms will decay. For example, a source of radioactive gold (198Au) with a half-life of 2.69 days, , started with 100106 atoms, after 2.69 days there would be 50 106 remaining, after 5.38 days 25 106, after 8.07 days 12.5 106.,EXPONENTIAL DECAY OF A RADIOACTIVE ISOTOPEHALF-LIFE,EXPONENTIAL DECAY OF A RADIOACTIVE ISOTOPEHALF-LIFE,Mathematical relation数学关系:,substituting t = th , 2th, 3th. （取代） The number, N, after these times is N0 /2, N0 /4, N0 /8,EXPONENTIAL DECAY OF A RADIOACTIVE ISOTOPEHALF-LIFE,Example 1-8. Calculate the number of atoms of 198Au (th = 2.69 days) after 7 days if initially （开始,最初）there were 108 atoms present.,We now determine（测定） with a calculator（计算器） that 22.606.06,atoms,e0.693 = 2.00,N = N0(2)-t/th = N0(e0.693) -t/th = N0e -0.693t/th,Decay time (in units of half-lives) =,Transformation constant 变换衰变,转变常数,N = -Nt , provided（只有才） t 1,dN = - N dt,N = N0e-t,Exponential growth of cells 细胞的指数生长,N = + Nt,its solution leads to,N = N0et and =,Exponential killing of cells,N = - ND,N = N0e-D = N0e-D/D0,Graphs showing exponential growth of cells and exponential killing（指数式消灭） of cells.,Exponential attenuation 指数减弱,N = -Nx,N = N0e-x, the linear attenuation coefficient线性衰减系数,the solution is :,is called the half-value thickness （半吸收厚度;半值层;强度减半厚度） , or half-value layer,Summary of Exponential Behavior,summary,Mass and energy Mass and velocity Exponential behavior, ,The Production and Properties of X Rays Part One,BME College Sherman sheen,X-Ray Tubes（X射线管） and Simplified Circuit单一化的线路,Q: How to produce X radiation?,Substance(物质，物) bombarded (轰击)by high speed electrons X-ray tube,Q: Structure of an X ray tube?,cathode（阴极）, anode（阳极）, filament(灯丝), focusing cup(聚焦杯),X-Ray Tubes and Simplified Circuit,A big problem ? -efficiency（效率, 效能） -Nobel prize,Understand X-ray tube in a circuit space charge （空间电荷） effect,saturation 饱和（状态）,tube voltage （管电压 ）increased,filament emission（灯丝发射）,X-Ray Tubes and Simplified Circuit,X-Ray Tubes and Simplified Circuit,Three important parameters（参量）,Tube current 管电流 Filament current 灯丝电流 KV anode-cathode 伏特 阳极阴极,A kind of special tubes grid-controlled tubes 控制栅电子管 rapid switching and short exposure time 迅速的转变和短暴露时间,Self-rectified （自整流） X ray circuit,Self-rectified X ray circuit 自我整流的X光线路,Some basic concepts transformer变压器 iron core铁芯 primary winding初级线圈 secondary winding复卷绕组 line compensate 线补偿 milliammeter毫安表 filament control灯丝调节,Alternating Currents & Voltages 交流电电压,Rectification（整流）,the target of an x ray tube,hot enough to emit（发出，射出） electrons,electrons will flow from anode（阳极） to cathode（阴极）,the inverse cycle逆循环,the delicate filament（细灯丝） will be destroyed,Silicon rectifier硅整流器,Half wave & full wave（全波）,Three phase units三相单位,Anode and Cathode Structure,Diagnostic x ray tubes,produce a sharp shadow picture,“point source“ and “very short exposure“,the line focus tube 行聚焦管,rotating anode tube旋转阳极管,Diagrams illustrating anode construction and focal spots（焦斑(点)）. (a) Line focus fixed anode（行聚焦固定的阳极）. (b) Line focus rotating anode（旋转阳极）, viewed from the end. (c) Line focus rotating anode viewed from the side. (d) Alternative arrangement（间隔布置） of rotating anode using two separate “tracks“ at different angles as in the Siemens “Biangulix“ series. （替换以不同的角度使用两个分开 “ 轨道 “ 的阳极为在姆欧的新项目中 “ Biangulix“ 系列的间隔布置）。,Rotating anode tube（旋转阳极管 ）, adapted from diagram图解、示意图 by Philips.,Anode and Cathode Structure,Radiotherapy x ray tubes,Large average energy & focal spot 焦斑(点),Problem: secondary emission次级发射,Hooded anode被罩上的阳极,Hooded anode therapy tube 被罩上的阳极治疗管 adapted from diagram by Philips 从飞利浦公司的图表适应,summary,X-ray tube and simplified circuit X射线管和单一化线路 Rectification 整流 Three phase unit 三相单位 Anode and cathode structure 阳极和阴极结构, ,The Production and Properties of X Rays Part Two,BME College Sherman sheen,Ratings of Diagnostic Tubes诊断管的等级，类别,First, the focal spot 焦斑(点)must not be loaded beyond a certain power input. （负载超过特定输入功率） Second, the anode must not be loaded by successive exposures beyond a certain limit.（负载超过一个特定界限的连续曝光） Finally the housing（外壳, 外罩） must not be expected to dissipate its energy at rates beyond a certain value. （预期在特定的价值之外的比率驱散它的能量),Example 2-1. Calculate the rise in temperature(升温) of a rotating anode after an exposure of 100 mA for 2 s at constant potential of 100 kV. Assume (假设)the target to have a mass of 500 g and the surface area of the bombarded region(被轰击的区域) to be 30 cm2 ; take the density of tungsten（钨的密度） to be 19.3 g/cm3 and specific heat（比热） 0.03 cal g-1 oC-1. Perform the calculations for two limiting conditions（限制条件）: (a) assume the heat instantly distributes itself over the whole of the anode and none is lost by heat transfer（假设热量立即扩散到整个阳极且没有传热的损失）; (b) assume no heat escapes from the immediate area of the bombarded region but is concentrated to a depth of 1 mm under the bombarded area.（ 假设没有热量从当前被轰击的区域逃出但是集中到在被轰击的区域下面的 1 毫米的深度）,Energy input （能量输入） = 100103 V0.1A2s =2104J,Heat input to anode = 2104J = 2 104/4.18 cal 5103 cal,For whole anode, thermal capacity（热容量） = 500g0.03 cal g-1 OC-1 =15 cal OC-1,(a) Rise in temperature =,(b) Mass of bombarded volume = 300.1cm319.3 g cm-3 = 58g,Rise in temperature =,4.18J=1 calorie卡路里, 卡(热量单位),the average tube current in mA, the peak voltage (峰值电压)in kV, the exposure time（曝光时间） in seconds,HU: a heat unit(热量单位),HU = voltage (kV)current (mA)time (s),Energy deposited（能源储存 ） 0.75 HU joules,In practical engineering（在实际的工程学中）:,X ray Spectra（X光谱）,Interactions(相互作用) of Electrons with the Target to Give X Rays (X光),ionizational collisions(离子化碰撞)_ ionization（电离） produced, delta rays（ 三角线）, heat energy（热能）, radiative collisions（辐射碰撞）,high speed electron hitting(碰撞) mass,Chances depend on the energy of the electron,Typical electron interactions with a target 典型的一个目标的电子相互作用,Characteristic Radiation 标识辐射,Critical X ray Absorption Energies (keV) X光吸收能量,Principal Emission Lines in keV for Tungsten and Molybdenum 钨和钼在千电子伏特的主要发射谱线,White Radiation（白光）, or Bremsstrahlung（轫致辐射）,(a) paths （轨迹）of the electron into the target (b) change in direction at each interaction （每交互作用的方向改变） (c) chance of an ionizational loss and the chance of a radiation loss in each increment（增长） of path (d) direction of emission（排放,散发,发出） of the bremsstrahlung (e) attenuation （变薄 ）and scattering（散射） in emerging（显露） from the target.,THE ANGULAR DISTRIBUTION （角分布;角向分布）OF X RAYS,Thin Target 薄靶 bombarding （轰击）a foil of aluminum（铝箔） 200 nm thick with 34 keV electrons: maximum intensity（强烈）-550 intensity in forward direction-small intensity in backward direction-zero Increase energy of the bombarding electrons : energy forward direction,THE ANGULAR DISTRIBUTION OF X RAYS,Thick Target （厚靶） maximum yield（产出） is usually 5 to 10o to the cathode side （阴极,负极） heel effect（倾斜效果） :reduced intensity on the anode side,summary,Ratings of Diagnostic tubes X-ray spectra Interactions of Electrons with the target to give X rays Characteristic radiation White radiation or bremsstralung Angular distribution of X rays,The Fundamentals（原理） of Nuclear Physics Part one,BME College Sherman sheen,The Physics of Radiology,Natural Radioactivity 天然放射性,General state of particles粒子的一般状态,Continual motion持续不断的运动 Uncertainty for a single