原子物理簡介
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原子物理簡介. Structure of matter---The atoms. All matter is composed of individual entities called elements. Each element is distinguishable from the others by the physical and chemical properties of its basic components --- the atom

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原子物理簡介

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3809910

原子物理簡介


Structure of matter the atoms

Structure of matter---The atoms

  • All matter is composed of individual entities called elements. Each element is distinguishable from the others by the physical and chemical properties of its basic components --- the atom

  • Each atom consists of a small central core, the nucleus, where most of the atomic mass is located and a surrounding "cloud" of electrons moving in orbits around the nucleus.


Structure of matter the atoms1

Structure of matter---The atoms

  • The radius of the atom (radius of the electronic orbits) is approximately 10-10 m

  • The nucleus has a much smaller radius, namely, about 10-14 m

  • Thus, for a particle of size comparable to nuclear dimensions, it will be quite possible to penetrate several atoms of matter before a collision happens


Structure of matter the atoms2

Structure of matter---The atoms

  • it is important to keep track of those particles that have not interacted with the atoms

  • --- the primary beam

  • and those that have suffered collisions

  • --- the scattered beam


Structure of matter the nucleus

Structure of matter---The nucleus

  • The properties of atoms are derived from the constitution of

    • their nuclei and

    • the number and the organization of the orbital electrons

  • The nucleus contains protons and neutrons. Whereas protons are positively charged, neutrons have no charge


Structure of matter the nucleus1

Structure of matter---The nucleus

  • The number of protons in the nucleus is equal to the number of electrons outside the nucleus, thus making the atom electrically neutral

  • Atomic nomenclature

X : atomic symbol

A : atomic mass number

Z : atomic number

* A = Z + N (質量數=質子數+中子數)


Terms used to describe a nucleus

Terms used to describe a nucleus

Ei-Ef


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原子的分類

  • 1.同位素(isotope):相同質子數,不同中子數

  • 2.同中素(isotone):相同中子數,不同質子數

  • 3.同重素(isobar) :相同質量數,不同中子數,

  • 不同質子數

  • 4.同質異能素(isomer):相同核種,不同核子能階


Structure of matter the nucleus2

Structure of matter---The nucleus

  • Certain combinations of neutrons and protons result in stable (nonradioactive) nuclides than others

  • stable elements in the low atomic number

    • --- N = Z

  • as Z increases beyond about 20, the N/P ratio for stable nuclei becomes > 1 and increases with Z


Structure of matter the nucleus3

Structure of matter---The nucleus

combinations of neutrons and protons result in stable


Atomic mass and energy units

Atomic mass and energy units

  • atomic mass unit (amu)

    • defined as 1/12 of the mass of a nucleus

  • Thus the nucleus of is arbitrarily assigned the mass equal to 12 amu


Masses and charges of the main subatomic particles

Masses and charges of the main subatomic particles


Atomic mass and energy units1

Atomic mass and energy units

  • mass defect ( binding energy)

    • the mass of an atom is not exactly equal to the sum of the masses of constituent particles

    • a certain mass is destroyed and converted into energy that acts as a "glue" to keep the nucleons together


The nucleus

THE NUCLEUS

Binding Energy


The nucleus1

THE NUCLEUS

  • Binding Energy

    • Mass defect

    • The difference between the atomic weight and the sum of the weights of the parts = W - M

      W = ZmH + ( A-Z )mn

      M = atomic weight

      BE = ( W – M )amu × 931 MeV/amu


Atomic mass and energy units2

Atomic mass and energy units

  • The basic unit of energy is the joule (J)

    • equal to the work done when a force of 1 newton acts through a distance of 1 m

  • Energy unit in atomic and nuclear physics

    • electron volt ( eV ),

    • defined as the kinetic energy acquired by an electron in passing through a potential difference of 1 V


Atomic mass and energy units3

Atomic mass and energy units


Distribution of orbital electrons

Distribution of orbital electrons

  • Rutherford’s atomic model (1911)


Distribution of orbital electrons1

Distribution of orbital electrons

  • Bohr atomic model (1913)


Bohr s postulates

Bohr’s postulates

  • 1.An electron in an atom moves in a circular orbit about the nucleus under the influence of the Coulomb attraction between the electron and the nucleus, and obeying the law of classical mechanics.

  • 2.Instead of the infinity of orbits which would be possible in classical mechanics, it is only possible for an electron to move in an orbit for which its orbital angular momentum L is an integral multiple of Planck’s constant h, divided by 2π. (L=nħ)


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  • 3.Despite the fact that it is constantly accelerating, an electron moving in such an allowed orbit does not radiate electromagnetic energy. Thus its total energy E remains constant.

  • 4.Electromagnetic radiation is emitted if an electron, initially moving in an orbit of total energy Ei, discontinuously changes its motion so that it moves in an orbit of total energy Ef. The frequency of the emitted radiation ν is equal to the quantity (Ei - Ef) devided by Planck’s constant h. (hν= Ei - Ef)


Atomic energy levels

ATOMIC ENERGY LEVELS

  • Energy level diagram of the tungsten atom


Nuclear forces

NUCLEAR FORCES

  • There are four different forces in nature, in the order of their strengths :

    • strong nuclear force

    • electromagnetic force

    • weak nuclear force

    • gravitational force


Nuclear forces1

NUCLEAR FORCES

  • strong nuclear force

    • responsible for holding the nucleons together in the nucleus

  • electromagnetic force

    • force between charged nucleons is quite strong, but it is repulsive and tends to disrupt the nucleus


Nuclear forces2

NUCLEAR FORCES

  • weak nuclear force

    • appears in certain types of radioactive decay

  • gravitational force

    • in the nucleus is very weak and can be ignored


Nuclear forces3

NUCLEAR FORCES

  • The strong nuclear force is a short-range force that comes into play when the distance between the nucleons becomes smaller than the nuclear diameter


Nuclear energy levels

NUCLEAR ENERGY LEVELS

  • The shell model of the nucleus assumes that the nucleons are arranged in shells, representing discrete energy states of the nucleus similar to the atomic energy levels

  • If energy is imparted to the nucleus, it may be raised to an excited state, and when it returns to a lower energy state , it will give off energy equal to the energy difference of the two states.


Nuclear energy levels1

NUCLEAR ENERGY LEVELS

  • Sometimes the energy is radiated in steps, corresponding to the intermediate energy states, before the nucleus settles down to the stable or ground state


Particle radiation

PARTICLE RADIATION

  • Radiation

    • emission and propagation of energy through space or a material medium

  • particle radiation

    • energy propagated by traveling corpuscles that have a definite rest mass and within limits have a definite momentum and defined position at any instant


Particle radiation1

PARTICLE RADIATION

  • Besides protons, neutrons, and electrons , many other atomic and subatomic particles have been discovered

  • Interact with matter and produce varying degrees of energy transfer to the medium


Electromagnetic radiation

ELECTROMAGNETIC RADIATION

  • Wave Model

    • in terms of oscillating electric and magnetic fields

    • the mode of energy propagation for such phenomena as light waves, radio waves, microwaves, ultraviolet rays, g-rays, and x-rays

    • with the speed of light ( 3 x 108 m/sec in vacuum)


Electromagnetic radiation1

Electromagnetic radiation

  • A. Wave model

  • λ= C/ν


Electromagnetic radiation2

ELECTROMAGNETIC RADIATION

  • Quantum Model

    • wavelength becomes very small or the frequency becomes very large, the dominant behavior of electromagnetic radiations can only be explained by considering their particle or quantum nature


Electromagnetic radiation3

Electromagnetic radiation

  • B. Quantum model

  • E = hν= hc /λ

  • h : Planck’s constant (6.62×10-34 J‧sec)

  • c:3×108 m/sec

  • E (keV) = 1.24 /λ(nm)


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放射物理簡介


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X 射線的產生


The mechanism of x ray production

The mechanism of x–ray production

  • 1. Characteristic x-rays


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The mechanism of x–ray production

2. Bremsstrahlung x-rays (braking radiation)


Diagnostic x ray tube thick target

Diagnostic x-ray tube (thicktarget)


Spatial distribution of therapeutic x rays thin target

Spatial distribution of therapeutic x-rays (thin target)


The efficiency of bremsstrahlung x ray production

The efficiency of bremsstrahlungx-ray production

  • Efficiency is defined as the ratio of output energy emited as x-rays to the iuput energy deposited by electrons.

Efficiency = 9 x 10-10 ZV

Z︰atomic number of target

V︰tubevoltage


X ray energy spectra

X-ray energy spectra


Operating characteristics

Operating characteristics


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醫用直線加速器之結構


Nuclear tramsformatioms

NUCLEAR TRAMSFORMATIOMS


Nuclear tramsformatioms1

NUCLEAR TRAMSFORMATIOMS

  • RADIOACTIVITY

    • Radioactivity, first discovered by Henri Becquerel in 1896, is a phenomenon in which radiation is given off by the nuclei of the elements

    • This radiation can be in the form of particles , electromagnetic radiation, or both.


Nuclear tramsformatioms2

NUCLEAR TRAMSFORMATIOMS

  • RADIOACTIVITY

    • a radioactive nucleus has excess energy that is constantly redistributed among the nucleons by mutual collisions

    • As a matter of probability, one of the particles may gain enough energy to escape from the nucleus, thus enabling the nucleus to achieve a state of lower energy


Nuclear tramsformatioms3

NUCLEAR TRAMSFORMATIOMS

  • RADIOACTIVITY

    • Also, the emission of a particle may still leave the nucleus in an excited state. In that case, the nucleus will continue stepping down to the lower energy states by emitting particles or g rays until the stable or the ground state has been achieved.


Nuclear tramsformatioms4

NUCLEAR TRAMSFORMATIOMS

  • DECAY CONSTANT

    • where l is a constant of proportionality called the decay constant


Nuclear tramsformatioms5

NUCLEAR TRAMSFORMATIOMS

  • ACTIVITY

    • The rate of decay is referred to as the activity of a radioactive material

    • where A is the activity remaining at time t, and A0 is the original activity equal to lN0


Nuclear tramsformatioms6

NUCLEAR TRAMSFORMATIOMS

  • ACTIVITY

    • The unit of activity is the curie (Ci) :

    • 1 Ci = 3.7 x 1010 disintegrations/sec (dps)

    • The SI unit for activity is becquerel (Bq). The becquerel is a smaller but more basic unit than the curie and is defined as:

    • 1 Bq = l dps = 2.70 x 10-11 Ci


Nuclear tramsformatioms7

NUCLEAR TRAMSFORMATIOMS

  • THE HALF-LIFE AND THE MEAN LIFE

    • The term half-life ( T1/2 ) of a radioactive substance is defined as the time required for either the activity or the number of radioactive decay to half the initial value


Nuclear tramsformatioms8

NUCLEAR TRAMSFORMATIOMS

  • THE HALF-LIFE AND THE MEAN LIFE

    • The mean or average life is the average lifetime for the decay of radioactive atoms


Nuclear tramsformatioms9

NUCLEAR TRAMSFORMATIOMS

  • Example

    • 1. Calculate the number of atoms in 1g of 226Ra.

    • 2. What is the activity of 1 g of 226Ra (half-life = 1,622 years)?


Nuclear tramsformatioms10

NUCLEAR TRAMSFORMATIOMS

  • specific activity

    • The activity per unit mass of a radionuclide is termed

    • One reason why cobalt-60 is preferable to cesium-137, in spite of its lower half-life (5.26 years for 60Co versus 30.0 years for 137Cs) is its much higher specific activity


Nuclear tramsformatioms11

NUCLEAR TRAMSFORMATIOMS

  • Example

    • 1) Calculate the decay constant for cobalt-60 ( T1/2 = 5.26 years) in units of month-1.

    • 2) What will be the activity of a 5,000-Ci 60Co source after 4 years?


Modes of radioactive decay

MODES OF RADIOACTIVE DECAY

  • a Particle Decay

    • Radioactive nuclides with very high atomic numbers (greater than 82) decay most frequently with the emission of an a particle

    • where Q represents the total energy released in the process and is called the disintegration energy


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Alpha Decay (阿伐衰變)


Modes of radioactive decay1

MODES OF RADIOACTIVE DECAY

  • b Particle Decay

    • accompanied by the ejection of a positive or a negative electron from the nucleus, is called the b decay

  • antineutrino and neutrino, are identical panicles but with opposite spins. They carry no charge and practically no mass.


Modes of radioactive decay2

MODES OF RADIOACTIVE DECAY

  • b Particle Decay---Negatron Emission

    • with an excessive number of neutrons or a high neutron-to-proton (n/p) ratio


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Beta Decay (貝他衰變)


Modes of radioactive decay3

MODES OF RADIOACTIVE DECAY

  • b Particle Decay---Positron Emission

    • Positron-emitting nuclides have a deficit of neutrons, and their n/p ratios are lower than those of the stable nuclei of the same atomic number


Modes of radioactive decay4

MODES OF RADIOACTIVE DECAY

  • b Particle Decay---Positron Emission


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Positron Emission (正子發射)


Modes of radioactive decay5

MODES OF RADIOACTIVE DECAY

  • b Particle Decay---Electron Capture

    • The electron capture is a phenomenon in which one of the orbital electrons is captured by the nucleus, thus transforming a proton into a neutron


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Electron Capture (電子捕獲)


Modes of radioactive decay6

MODES OF RADIOACTIVE DECAY

  • b Particle Decay---Internal Conversion

    • The excess nuclear energy is passed on to one of the orbital electrons, which is then ejected from the atom. The process can be crudely likened to an internal photoelectric


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Internal Conversion (內轉換)

conversion

electron

electron

vacancy


Interaction of radiation with matter

Interaction of Radiation with Matter

  • Matter consists of atomic nuclei and extranuclear electrons. Radiation may interact with either or both of these constituents of matter

  • In all instances, excitation and ionization of the absorber atoms results from their interaction with the radiation. Ultimately, the energy transferred either to tissue or to a radiation shield is dissipated as heat


Beta rays

BETA RAYS

  • Mechanisms of Energy Loss

    • Ionization and Excitation


Alpha rays

ALPHA RAYS

  • Range-Energy Relationship

    • Alpha rays are the least penetrating of the radiations. In air, even the most energetic alphas from radioactive substances travel only several centimeters


Gamma rays

GAMMA RAYS

  • Interaction Mechanisms

    • Photoelectric absorption

    • Compton scattering

    • Pair production

    • Photodisintegration


Gamma rays1

GAMMA RAYS

  • Pair Production

    • A photon energy exceeds 1.02 MeV

    • total kinetic energy of positron-electron pair is nearly equal to hf-2m0c2


Gamma rays2

GAMMA RAYS

  • Pair Production

    • the probability of this process increases rapidly with atomic number


Gamma rays3

GAMMA RAYS

  • Pair Production

    • When the positron has expended all of its kinetic energy, it combines with an electron to produce two quanta of 0.51 MeV each of annihilation radiations


Gamma rays4

GAMMA RAYS

  • Compton scattering

    • an elastic collision between a photon and a "free" electron (an electron whose binding energy to an atom is very much less than the energy of the photon)


Gamma rays5

GAMMA RAYS

  • Compton scattering


Gamma rays6

GAMMA RAYS

  • Photoelectric Absorption

    • the photon disappears, is an interaction between a photon and a tightly bound electron whose binding energy is equal to or less than the energy of the photon


Gamma rays7

GAMMA RAYS

  • Photoelectric Absorption


Gamma rays8

GAMMA RAYS

  • Photodisintegration

    • the absorber nucleus captures a gamma ray and, in most instances, emits a neutron

  • The above reaction has a definite threshold, 10.86 MeV.


Gamma rays9

GAMMA RAYS

  • Combined Effects

    • The total attenuation coefficient

  • The energy absorption coefficient


Neutrons

NEUTRONS

  • Classification

    • a neutron undergoes depends very strongly on its energy

      • Fast neutron, E > 0.1MeV

      • Thermal neutrons, E ~ 0.025 eV

      • Intermediate neutrons, resonance neutrons, and slow neutrons, energy between thermal and fast


Neutrons1

NEUTRONS

  • Interaction

    • All neutrons, at the time of their birth, are fast.

    • Generally, fast neutrons lose energy by colliding elastically with atoms in their environment, and then, after being slowed down to thermal or near thermal energies, they are captured by nuclei of the absorbing material


Neutrons2

NEUTRONS

  • Interaction

    • The removal of neutrons from the beam is thus given by:

  • The total cross section is the sum of the cross sections for the various possible reactions


Neutrons3

NEUTRONS

  • Capture reaction


Neutrons4

NEUTRONS

  • Neutron Activation

    • Activation by neutrons is important to the health physicist for several reasons

    • any substance that was irradiated by neutrons may be radioactive

    • it provides a convenient tool for measuring neutron flux


Neutrons5

NEUTRONS

  • Neutron Activation


Absorbed dose

吸收劑量(absorbed dose)

  • 單位物質質量吸收游離輻射所釋予之平均能量

  • D = ΔE/Δm

  • SI單位:焦耳/公斤 (J/kg)


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輻射劑量之單位

  • 吸收劑量單位:

  • 1 rad(雷得) = 100 erg/g

  • = 10-2 J/kg

  • 1 Gy(戈雷) = 1 J/kg

  • = 100 rad

  • * 1 J(焦耳) = 107 erg (耳格)


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劑量與曝露之單位轉換

  • 劑量的單位 : rad (雷得)

  • 曝露的單位 : R (侖琴)

  • 1.在空氣中

  • 1 R 相當於 0.87 rad

  • 2.在組織中

  • 1 R 相當於 0.93 rad

  • *1 R = 2.58×10-4 C/kg


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Biological Effects of Radiation


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影響生物效應的因子

  • 輻射種類與能量-輻射品質(radiation quality)

  • 輻射劑量(radiation dose)

  • 生物效應種類

    • DNA效應

    • 細胞效應

    • 個體效應

      • 確定效應(deterministic effects)

      • 機率效應(stochastic effects)

        • 癌症 (cancers):器官劑量

        • 遺傳效應 (hereditary effects):生殖腺劑量


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Stochastic and Non-Stochastic Effects

  • 機率效應(癌病、遺傳效應等)

    • 效應發生的機率(風險)與劑量呈正比;效應的嚴重程度與劑量無關;沒有低限劑量。

  • 非機率效應(皮膚紅斑、白內障等)

    • 效應的嚴重程度與劑量呈正比;有低限劑量。當劑量小於低限劑量時,效應不會發生;當劑量大於低限劑量時,效應確定發生。


Deterministic effects

小於低限劑量

效應不會發生

大於低限劑量

效應一定發生

劑量愈高

愈嚴重

Deterministic Effects (確定效應)

  • 當劑量小於低限劑量(threshold dose)時效應確定不發生

  • 當劑量大於低限劑量時效應確定會發生

  • 效應發生後嚴重程度(severity)與劑量呈比例


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Linear and Non-threshold

(LNT) Hypothesis

Characteristics of Stochastic and

Non-Stochastic Effects


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Threshold Dose (低限劑量)


Radiation induced cancer

Radiation-induced Cancer (輻射誘發癌症)

  • 效應發生的機率與劑量呈正比

1 Sv

2 Sv

3 Sv

  • 效應的嚴重程度與劑量無關

  • 低限劑量可能不存在


Radiation induced hereditary disease

Radiation-induced Hereditary Disease (輻射誘發遺傳疾病)

  • 生殖腺(男:睪丸,女:卵巢)劑量引起之突變所導致之遺傳疾病


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Direct Action

分子或組織直接因輻射造成游離而解離

e.g.

LD50/30 day dose: 50%在30天內致

死之劑量

4 Gy (for person of gamma ray)


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Direct Action

  • If any form of radiation-x- or y-rays, charged or uncharged particles-is absorbed in biologic material, there is a possibility that it will interact directly with the critical targets in the cells.

  • The atoms of the target itself may be ionized or excited, thus initiating the chain of events that leads to a biologic change. This is called direct action of radiation ;

  • it is the dominant process if radiations with high linear energy transfer (LET), such as neutrons or a-particles, are considered.


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Direct Action

Alternatively, the radiation may interact with other atoms or molecules in the cell (particularly water) to produce free radicals that are able to diffuse far enough to reach and damage the critical targets.

This is called indirect action of radiati0n.


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Indirect Action: Free Radicals (自由基)

  • About two thirds of the biologic damage by x-rays is caused by indirect action.


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Acute Exposure Effects


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Radiation Effects---Delayed Effects

  • Radiation carcinogenesis is a stochastic effect

  • Latency refers to the time interval between irradiation and the appearance of the malignancy

  • The shortest latency is for leukemia, with a peak at 5 to 7 years. For solid tumors, the latency may extend for 60 years or more.


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Radiation Effects---Delayed Effects

  • Regardless of the age at exposure, radiation-induced malignancies tend to appear at the same age as spontaneous malignancies of the same type

  • Indeed, for solid cancers, the excess risk is apparently more like a lifelong elevation of the natural age-specific cancer risk.


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Radiation Effects---Delayed Effects

  • Based on reports of the UNSCEAR and BElR V committees, the ICRP suggests a risk estimate of excess cancer mortality in

    • working population

  • per sievert

  • for high doses and high dose rates

    • per sievert

      for low doses and low dose rates


Radiation track

Radiation Track (輻射徑跡):輻射品質

游離密度小

LET小

電子

a粒子

游離密度大

LET大

DNA


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Radiation Quality (輻射的質)

A輻射

B輻射

吸收劑量:

DA

DB

相同生物效應

量:吸收劑量(D)

質:相對生物效應(RBE)

RBE=D200keV X-ray/Dradiation


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RBE(相對生物效應)、LET(直線能量轉移)

Q

RBE

A、B兩輻射,產生相同生物效應之

吸收劑量為DA及DB,則相對生物效應(relative biological effectiveness, RBE)的定義為:

RBEA/RBEB=DB/DA


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Q(射質因數)、wR(輻射加權因數)

ICRP-26

H=QD

H=dose equivalent (等效劑量), unit=Sv (西弗)

Q=quality factor (射質因數)

D=absorbed dose (吸收劑量), unit=Gy (戈雷)

ICRP-60

HT,R=wRDT,R

HT,R=equivalent dose (T組織R輻射的等價劑量)

wR=radiation weighting factor (輻射加權因數)

DT,R=absorbed dose (T組織R輻射的吸收劑量)


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Dose Equivalent (等效劑量)

Equivalent Dose (等值劑量)

ICRP 26

ICRP 60


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Q與wR的建議值


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Equivalent Dose (等價劑量)


Effective dose

Effective Dose (有效劑量)


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Comparison Between Tissue Weighting Factors in ICRP-26 and ICRP-60

Tissue (WT,26)

Tissue (WT,60)

Thyroid (0.03)

Lung (0.12)

Breast (0.15)

Gonads (0.25)

Bone surface (0.03)

Red bone marrow (0.12)

Remainder (0.30)

Thyroid (0.05)

Oesophagus (0.05)

Breast (0.05)

Lung (0.12)

Stomach (0.12)

Liver (0.05)

Colon (0.12)

Bladder (0.05)

Gonads (0.20)

Skin (0.01)

Bone surface (0.01)

Red bone marrow (0.12)

Remainder (0.05)


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Risk Coefficient (風險係數)


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Weighting Risk Coefficient (加權風險係數)


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輻射防護目的

  • 防止確定效應之損害發生(絕對安全)。

  • 抑低機率效應之發生率,至可接受的低水平(相對安全)。

劑量限度


Organizations that set standards

ORGANIZATIONS THAT SET STANDARDS

1925 -International Commission on Radiation Units and Measurements (ICRU) 國際輻射單位與度量委員會

1928 -International Commission on Radiological Protection (ICRP) 國際放射防護委員會

1946 -National Council on Radiation Protection and Measurements (NCRP) 美國國家輻射防護及度量委員會

1957 -International Atomic Energy Agency (IAEA) 國際原子能總署

Nuclear Regulatory Commission (NRC) 美國核能管制委員會

中華民國行政院原子能委員會(Atomic Energy Council)

1977 -ICRP 261987 – NCRP 91

1991 -ICRP 60


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91.01.30游離輻射防護法

91.12.11輻射防護人員管理辦法

91.12.11輻射防護管理組織及輻射防護人員設置標準

91.12.25游離輻射防護法施行細則

91.12.25放射性物質或可發生游離輻射設備操作人員管理辦法

92.01.22放射性物質與可發生游離輻射設備及其輻射作業管理辦法

92.01.22放射性物質生產設施運轉人員管理辦法

92.01.29輻射源豁免管制標準

92.01.30游離輻射防護安全標準


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Effective Dose Equivalent Limits


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游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (二)等效劑量:指人體組織或器官之吸收劑量與射質因數之乘積,其單位為西弗,射質因數依附表一之一(一)規定。

      • 射質因數Q(L)為以國際放射防護委員會在第六十號報告中規定之水中非限定線性能量轉移L表示之。


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游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (三)個人等效劑量:指人體表面定點下適當深度處軟組織體外曝露之等效劑量。對於強穿輻射,為十毫米深度處軟組織;對於弱穿輻射,為○‧○七毫米深度處軟組織;眼球水晶體之曝露,為三毫米深度處軟組織,其單位為西弗。


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游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (五)等價劑量:指器官劑量與對應輻射加權因數乘積之和,其單位為西弗,輻射加權因數依附表一之一(二)規定。


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游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (六)約定等價劑量:指組織或器官攝入放射性核種後,經過一段時間所累積之等價劑量,其單位為西弗。一段時間為自放射性核種攝入之日起算,對十七歲以上者以五十年計算;對未滿十七歲者計算至七十歲。


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游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (七)有效劑量:指人體中受曝露之各組織或器官之等價劑量與各該組織或器官之組織加權因數乘積之和,其單位為西弗,組織加權因數依附表一之二規定。


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游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (七)有效劑量:指人體中受曝露之各組織或器官之等價劑量與各該組織或器官之組織加權因數乘積之和,其單位為西弗,組織加權因數依附表一之二規定。


3809910

游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (八)約定有效劑量:指各組織或器官之約定等價劑量與組織加權因數乘積之和,其單位為西弗。


3809910

游離輻射防護安全標準(97.1.1)

  • 第 二 條

    • 五、劑量:指物質吸收之輻射能量或其當量。

      • (九)集體有效劑量:指特定群體曝露於某輻射源,所受有效劑量之總和,亦即為該特定輻射源曝露之人數與該受曝露群組平均有效劑量之乘積,其單位為人西弗。


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游離輻射防護安全標準(97.1.1)

  • 第 七 條 輻射工作人員職業曝露之劑量限度,依下列規定:

    • 一、每連續五年週期之有效劑量不得超過一百毫西弗,且任何單一年內之有效劑量不得超過五十毫西弗。

    • 二、眼球水晶體之等價劑量於一年內不得超過一百五十毫西弗。

    • 三、皮膚或四肢之等價劑量於一年內不得超過五百毫西弗。


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游離輻射防護安全標準(97.1.1)

第 十一 條 雇主於接獲女性輻射工作人員告知懷孕後,應即檢討其工作條件,使其胚胎或胎兒接受與一般人相同之輻射防護。

前項女性輻射工作人員,其賸餘妊娠期間下腹部表面之等價劑量,不得超過二毫西弗,且攝入體內放射性核種造成之約定有效劑量不得超過一毫西弗。


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游離輻射防護安全標準(97.1.1)

第 十二 條 輻射作業造成一般人之年劑量限度,依下列規定:

一、有效劑量不得超過一毫西弗。

二、眼球水晶體之等價劑量不得超過十五毫西弗。

三、皮膚之等價劑量不得超過五十毫西弗。


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職業暴露之年劑量限度

  • 1.全身之有效等效劑量(HE)

  • HE ≦ 50 mSv/y or 5 rem/y

  • 2.眼球水晶體之等效劑量(HT)

  • HT≦ 150 mSv/y or 15 rem/y

  • 3.其他個別器官或組織之等價劑量(HT)

  • HT≦ 500 mSv/y or 50 rem/y


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一般民眾暴露之年劑量限度

  • 1.全身之有效劑量(HE)

  • HE ≦ 1 mSv/y or 0.1 rem/y

  • 2.眼球水晶體之等價劑量(HT)

  • HT≦ 15 mSv/y or 1.5 rem/y

  • 3.其他個別器官或組織之等價劑量(HT)

  • HT≦ 50 mSv/y or 5 rem/y


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體外輻射防護基本原則 — TSD

  • T(time) — Minimize time of exposure

  • S(shielding) — maximize amount of

  • shielding

  • D(distance) — Maximize diatance from

  • the source of radiation


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游離腔偵檢器(診斷型x光機)


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游離腔偵檢器


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熱發光劑量計(TLD)


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體外照射之屏蔽設計

  • 必須針對三種輻射實施屏蔽設計:

  • 1.原始輻射(primary radiation)

  • 2.散射輻射(scatter radiation)

  • 3.滲漏輻射(leakage radiation)


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治療室設計


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