is the process by which an unstable atomic nucleus loses energy by emitting ionizing particles or radiation. The emission is spontaneous in that the nucleus decnt nuclide, transforming to an atom of ays without collision with another particle. This decay, or loss of energy, results in an atom of one type, called the parea different type, named the daughter nuclide, 14C ------- 15N
Radioactive decay
• Atom (nuclei) yang mempunyai rasio proton – neutron berada di luar Belt of stability secara langsung akan mengalami radioactive decay secara Spontan• Tipe Decay tergantung dimana posisi atom berada relative terhadap band of stability • Radioactive particle are emitted with different kinetic energy - Energy change is related to the change in binding energy from reactant to product
Mode of decay Participating particles Daughter nucleusDecays with emission of nucleons:
Alpha decayAn alpha particle (A = 4, Z = 2) emitted from nucleus
(A − 4, Z − 2)
Proton emission A proton ejected from nucleus (A − 1, Z − 1)Neutron emission A neutron ejected from nucleus (A − 1, Z)
Double proton emissionTwo protons ejected from nucleus simultaneously
(A − 2, Z − 2)
Spontaneous fissionNucleus disintegrates into two or more smaller nuclei and other particles
—
Cluster decayNucleus emits a specific type of smaller nucleus (A1, Z1) smaller than, or larger than, an alpha particle
(A − A1, Z − Z1) + (A1, Z1)
Different modes of beta decay:
β− decay A nucleus emits an electron and an electron antineutrino
(A, Z + 1)
Positron emission (β+ decay)A nucleus emits a positron and a electron neutrino
(A, Z − 1)
Electron capture
A nucleus captures an orbiting electron and emits a neutrino – the daughter nucleus is left in an excited and unstable state
(A, Z − 1)
Double beta decayA nucleus emits two electrons and two antineutrinos
(A, Z + 2)
Double electron capture
A nucleus absorbs two orbital electrons and emits two neutrinos – the daughter nucleus is left in an excited and unstable state
(A, Z − 2)
Electron capture with positron emissionA nucleus absorbs one orbital electron, emits one positron and two neutrinos
(A, Z − 2)
Double positron emissionA nucleus emits two positrons and two neutrinos
(A, Z − 2)
Transitions between states of the same nucleus:
Isomeric transitionExcited nucleus releases a high-energy photon (gamma ray)
(A, Z)
Internal conversionExcited nucleus transfers energy to an orbital electron and it is ejected from the atom
(A
An example is the natural decay chain of 238U which is as follows:
decays, through alpha-emission, with a half-life of 4.5 billion years to thorium-234which decays, through beta-emission, with a half-life of 24 days to protactinium-234which decays, through beta-emission, with a half-life of 1.2 minutes to uranium-234which decays, through alpha-emission, with a half-life of 240 thousand years to thorium-230which decays, through alpha-emission, with a half-life of 77 thousand years to radium-226which decays, through alpha-emission, with a half-life of 1.6 thousand years to radon-222which decays, through alpha-emission, with a half-life of 3.8 days to polonium-218which decays, through alpha-emission, with a half-life of 3.1 minutes to lead-214which decays, through beta-emission, with a half-life of 27 minutes to bismuth-214which decays, through beta-emission, with a half-life of 20 minutes to polonium-214which decays, through alpha-emission, with a half-life of 160 microseconds to lead-210which decays, through beta-emission, with a half-life of 22 years to bismuth-210which decays, through beta-emission, with a half-life of 5 days to polonium-210which decays, through alpha-emission, with a half-life of 140 days to lead-206, which is a stable nuclide.
Nuclear Stability and Radioactive Decay
Beta decay
14C 14N + 0 + 6 7 -1
40K 40Ca + 0 + 19 20 -1
1n 1p + 0 + 0 1 -1
Decrease # of neutrons by 1
Increase # of protons by 1
Positron decay
11C 11B + 0 + 6 5 +1
38K 38Ar + 0 + 19 18 +1
1p 1n + 0 + 1 0 +1
Increase # of neutrons by 1
Decrease # of protons by 1
and have A = 0 and Z = 0
Electron capture decay
Increase # of neutrons by 1
Decrease # of protons by 1
Nuclear Stability and Radioactive Decay
37Ar + 0e 37Cl + 18 17-1
55Fe + 0e 55Mn + 26 25-1
Alpha decay
Decrease # of neutrons by 2
Decrease # of protons by 2212Po 4He + 208Pb
84 2 82
Spontaneous fission
252Cf 2125In + 21n98 49 0
23.2
1p + 0e 1n + 1 0-1
HITUNG PERUBAHAN ENERGI BINDINGPADA PROSES DECAY DIATAS ?
HALF-LIFEHALF-LIFE
• HALF-LIFEHALF-LIFE is the time that it is the time that it takes for 1/2 a sample to takes for 1/2 a sample to decompose.decompose.
• The rate of a nuclear The rate of a nuclear transformation depends only on transformation depends only on the “reactant” concentration.the “reactant” concentration.
HALF-LIFEHALF-LIFE
Decay of 20.0 mg of Decay of 20.0 mg of 1515O. What remains after 3 half-lives? After 5 half-lives?O. What remains after 3 half-lives? After 5 half-lives?
263Sg ----> 259Rf + 4He
Terjadi pada Solar Energi dan Proses terjadinya alam semesta
Terjadi pada proses bom nuklir dan reaktor nuklir kini
For each duration (half-life), one half of the substance decomposes.
For example: Ra-234 has a half-life of 3.6 days
If you start with 50 grams of Ra-234
After 3.6 days > 25 gramsAfter 3.6 days > 25 grams
After 7.2 days > 12.5 gramsAfter 7.2 days > 12.5 grams
After 10.8 days > 6.25 gramsAfter 10.8 days > 6.25 grams
The probability of decay (−dN/N) is proportional to dt:
The solution to this first-order differential equation is the following function:
Dimana,
The half life is related to the decay constant as follows:
Kinetics of Radioactive Decay
N daughter
rate = -N
t rate = N
N
t= N-
N = N0e(-t) lnN = lnN0 - t
N = the number of atoms at time t
N0 = the number of atoms at time t = 0
is the decay constant (sometimes called k)
Ln 2=
t½
23.3
k =
ACTIVITY CALCULATION
N = N0e(-t)
A = A0e(-t )
ECERCISE : Hitung sisa aktifitas Tritium setela tersimpan 26 tahun dari aktifitas semula 15 Ci, t1/2 tritium = 12,34 th
UNTUK HALF LIFE
2,303 Log 0,5/1 = -λ t½
λ = 0,693/t½
A sample of C14, whose half life is 5730 years, has a decay rate of 14 disintegration per minute (dpm) per gram of natural C. An artifact is found to have radioactivity of 4 dpm per gram of its present C, how old is the artifact?Using the above equation, we have:
Where:
years
years
Kinetics of Radioactive Decay
[N] = [N]0exp(-t) ln[N] = ln[N]0 - t
[N]
ln [N
]
23.3
• Arithmetically, melalui term half life kemudian dapat dihitung perubahan
jumlah/aktivitas zat radioaktive selama waktu tertentu• Graphycally, Mengunakan grafik semilog antara Aktivita radioaktiv Vs
waktu • Radioactive Equilibrium - Ratio Nomor atom pada proses reaksi decay zat radioaktive seperti
dibawah ini, 238U λu 234Th λTh 234Pa NTh / NU = λ U / λ Th
N Th / N U = t½ Th / t½ U
- Hal yang sama untuk atome decay dengan nomor atom yang kostan , Ratio Massa ebanding dengan ratio half life nya,
Massa X / Massa Y = t½ X . A X / t½ Y . A Y
Dari perhitungan ratio nomor atom dan massa ada decay reaction maka
dapat dihitung ratio dari ratio nomor atom dan mass dari hasil decay tersebut
Nuclear Reaction
Balancing Nuclear Equations
1. Conserve mass number (A). The sum of protons plus neutrons in the products must equal the sum of protons plus neutrons in the reactants.
1n0U235
92 + Cs13855 Rb96
371n0+ + 2
235 + 1 = 138 + 96 + 2x1
2. Conserve atomic number (Z) or nuclear charge.
The sum of nuclear charges in the products must equal the sum of nuclear charges in the reactants.
1n0U235
92 + Cs13855 Rb96
371n0+ + 2
92 + 0 = 55 + 37 + 2x023.1
• Alpha emissionAlpha emission
Note that mass number (A) goes down by 4 and atomic number (Z) goes down by 2.
Nucleons (nuclear particles… protons and neutrons) are rearranged but conserved
• Beta emissionBeta emission
Note that mass number (A) is unchanged and atomic number (Z) goes up by 1.
Positron (Positron (00+1+1): a positive electron): a positive electron
Electron capture: Electron capture: the capture of an electron
207 207
New elements or new isotopes of New elements or new isotopes of known elements are produced by known elements are produced by bombarding an atom with a bombarding an atom with a subatomic particle such as a proton subatomic particle such as a proton or neutron -- or even a much heavier or neutron -- or even a much heavier particle such as particle such as 44He and He and 1111B.B.
Reactions using neutrons are called Reactions using neutrons are called
reactions reactions because a because a ray is ray is usually emitted.usually emitted.
Radioisotopes used in medicine are Radioisotopes used in medicine are often made by often made by reactions. reactions.
Nuclear reactor
Cyclotron or accelerator
Is the probability that a bombarding particle (neutron) will produce a nuclear reaction
Cross section Unit is Barn (1 barn = 1024 cm-2)
Formula ; N = Φ x σ x nX Where, N = Total number of reaction Φ = Flux neutron σ = nuclear cross section n = number of nuclei in Cm3
X = is thickness of target in Cm
Example of a Example of a reaction reaction is is
production of radioactive production of radioactive 3131P P
for use in studies of P uptake for use in studies of P uptake
in the body.in the body.
31311515P + P + 11
00n ---> n ---> 32321515P + P +
Elements beyond 92 Elements beyond 92 (transuranium)(transuranium)
made starting with an made starting with an reaction reaction
2382389292U + U + 11
00n ---> n ---> 2392399292U + U +
2392399292U U ---> ---> 239239
9393Np + Np + 00-1-1
2392399393Np Np ---> ---> 239239
9494Pu + Pu + 00-1-1
Fission is the splitting of atomsFission is the splitting of atoms
These are usually very large, so that they are not These are usually very large, so that they are not
as stableas stable
Fission chain has three general steps:Fission chain has three general steps:
1.1. Initiation.Initiation. Reaction of a single atom Reaction of a single atom
starts the chain (e.g., starts the chain (e.g., 235235U + neutron)U + neutron)
2.2. PropagationPropagation. . 236236U fission releases U fission releases
neutrons that initiate other fissionsneutrons that initiate other fissions
3. 3. ___________ ___________ . . EXCERCISE , REACTION FISSION RANTAI URANIUM
Nuclear Fission
23.5
235U + 1n 90Sr + 143Xe + 31n + Energy92 54380 0
Energy = [mass 235U + mass n – (mass 90Sr + mass 143Xe + 3 x mass n )] x c2
Energy = 3.3 x 10-11J per 235U
= 2.0 x 1013 J per mole 235U
Combustion of 1 ton of coal = 5 x 107 J
Nuclear Fission
23.5
Nuclear chain reaction is a self-sustaining sequence of nuclear fission reactions.
The minimum mass of fissionable material required to generate a self-sustaining nuclear chain reaction is the critical mass.
Non-critical
Critical
a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235.
A control rod is a rod made of chemical elements capable of absorbing many neutrons without fissioning themselves. They are used in nuclear reactors to control the rate of fission of uranium and plutonium. Because these elements have different capture cross sections for neutrons of varying energies, the compositions of the control rods must be designed for the neutron spectrum of the reactor it is supposed to control. Light water reactors (BWR, PWR) and heavy water reactors (HWR) operate with "thermal" neutrons, whereas breeder reactors operate with "fast" neutrons.
Silver-indium-cadmium alloys, generally 80% Ag, 15% In, and 5% Cd, are a common control rod material for pressurized water reactors. The somewhat different energy absorption regions of the materials make the alloy an excellent neutron absorber. It has good mechanical strength and can be easily fabricated. It has to be encased in stainless steel to prevent corrosion in hot water.
A coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor promoting corrosion of the cooling system. Some applications also require the coolant to be an electrical insulator.
Currently about 103 Currently about 103
nuclear power nuclear power
plants in the U.S. plants in the U.S.
and about 435 and about 435
worldwide.worldwide.
17% of the world’s 17% of the world’s
energy comes from energy comes from
nuclear.nuclear.
Fusion small nuclei combine
2H + 3H 4He + 1n + 1 1 2 0
Occurs in the sun and other stars
Energy
23.6
Nuclear Fusion
2H + 2H 3H + 1H1 1 1 1
Fusion Reaction Energy Released
2H + 3H 4He + 1n1 1 2 0
6Li + 2H 2 4He3 1 2
6.3 x 10-13 J
2.8 x 10-12 J
3.6 x 10-12 J
Tokamak magnetic plasma confinement
Fusion Excessive heat can not be contained
Attempts at “cold” fusion have FAILED.
“Hot” fusion is difficult to contain
Mempelajari efek kimia yang di timbulkan oleh radiasi pengion bila ia diserap oleh materi
RADIASI : Emisi dan propagasi energi dalam udara dan suatu materi
RADIASI PENGION : Dapat mengionkan dan mengeksitasi target(Partikel bermuatan/ion /elektron, Gel elektromagnetik/gamma and sinar x, neutron)
IONISASI : Pelepasan elektron dari orbital suatu atom/molekul netral - elektron yang terikan paling lemah - terbentuk ion positif dan elektron bebas - hanya bisa ditimbulkan oleh radiasi pengion
EKSITASI : Perpindahan elektron ke orbital lebih tinggi dalam suatu atom/molekul netral menjadi atom/molekul mempunyai energi berlebih - kembali ke tingkat semula dengan disertai emisi cahaya atau - terjadi pemutusan ikatan yang lemah menghasilkan radikal bebas
IRADIASI : Paparan terhadap radiasi pengion (berdaya tembus)
Spektrum elektromagnetikRadiasi pengion
Radiasi non-pengion
Matahari/radio isotop
Tabung
sinar X
Matahari/lampu UV
Matahari/bola pijar
Matahari/pemanas
Pemancar/microwave oven
Pemancar
RADIOISOTOPE ALAM DAN BUATAN--------- FOTON DAN PARTIKEL
MESIN PEMERCEPAT (ACCELERATOR) PATIKEL----- BERKAS ELEKTRON, BERKAS ION
REAKTOR NUKLIR --------- BERKAS NETRONKARAKTERISASI RADIASI PENGION : DAYA TEMBUS DAN LET
Radiation pengion mempunyai daya tembus, tergantung pada jenis radiasi, energi foton/partikel dan kerapatan target
LET = Linier Energy Transer defined as the linier (distance) rate at which energy is lost by radiation traversing a material medium in unit kev/µ
DNA Sel Mikroba Patogenterkena radiasi menjadi tidak mampuberreplikasi dan mati
Radiasi Sinar Gamma terhadap Materi
Sinar gamma > sinar x > partikel beta > partikel alpha
Daya tembus
Partikel alpha > partikel beta > sinar x > sinar gamma
L E T
Linear energy transfer (LET) is a measure of the energy transferred to material as an ionizing particle travels through it. Typically, this measure is used to quantify the effects of ionizing radiation on biological specimens or electronic devices.
Linear energy transfer is closely related to stopping power. Whereas stopping power, the energy loss per unit distance, dE / dx
ENERGY RANGE
TYPE OF RADIATIONS LET VALUE IN WATER (kev/µ)
4 MeV – 9 MeV
0,5 MeV – 2 MeV
0,1 MeV - 2 MeV
-
Alpha 5 MeV
Beta 2 MeV
Gamma 1,25 MeV
X- Rays 200 KeV
140
0,2
0,3
3
PARTIKEL ALPHA - Daya tembus di udara antara 2,5 – 9 cm sedangkan untuk
aluminium antara 0,02 mm – 0,006mm - Electrostatic interaction dgn orbital electron menghasilkan
ionisasi dan ion pair (ion positive dan ejected electron) PARTIKEL BETA - Daya tembus 500 kali partikel alpha pada energi yang sama - Production of ion pair - Interaction of fast moving of beta particle produced
electromagnetic radiation (X-ray and gamma ray) near positive field of nucleus
disertai efect bremsstrahlung (slowing down radiation)
e-
e-e-
e-
Partikel pengion
elektronα
IONISASI
e-
e-
e-
e-
ionisasi
Partikel pengeksitasi
EKSITASI
REAKSI INTI
4Be9 + 2He4 ------------ 6C13 + 1H1
e-
e-
e- e-e-
e-
e-
Elektron dg energi Berkurang /Bremsstraslung
Sinar xß
-Ionisasi-Eksitasi-Bremstrahlung
Gamma Rays -Photoelectric absorption, gamma photon expends all of
its energy to eject an orbital electron from inner shell (beta
particle), energi foton < 1MeV seluruhnya diserap oleh
target -Comfton effect, only part of the original gamma energy
is used to eject a bound electron, and partly as gamma
scattered (energy gamma about 1 - 5 MeV) -Pair Production, interaksi menghasilkan pasangan
elektron-positron (energy gamma about 5 MeV), konversi foton oleh medan magnet inti menjadi elektron dan positron--- akan mengionisasi. Elektron dan positron akan berannihilasi menghasilkan sinar gamma lemah (0,51 MeV) yanh diserap target.
K-shell: 69.5 keV
L-shell: 12 keV
M-shell: 3 keV
N-shell: 1 keV
O-shell: 0.1 keV
Denise Moore, Sinclair Community College
The projectile electron interacts with the nuclear force field of the target tungsten atom
The electron (-) is attracted to the nucleus (+) The electron DOES NOT interact with the
orbital shell electrons of the atom Always produced = 100% of time
http://www.internaldosimetry.com/courses/introdosimetry/images/ParticlesBrem.JPG
As the electron gets close to the nucleus, it slows down (brems = braking) and changes direction
The loss of kinetic energy (from slowing down) appears in the form of an x-ray
The closer the electron gets to the nucleus the more it slows down, changes direction, and the greater the energy of the resultant x-ray
The energy of the x-ray can be anywhere from almost 0 (zero) to the level of the kVp
Rayleigh scattering Compton scattering Photoelectric absorption Pair production
Incident photon interacts with and excites the total atom as opposed to individual electrons
Occurs mainly with very low energy diagnostic x-rays, as used in mammography (15 to 30 keV)
Less than 5% of interactions in soft tissue above 70 keV; at most only 12% at ~30 keV
Predominant interaction in the diagnostic energy range with soft tissue
Most likely to occur between photons and outer (“valence”) shell electrons
Electron ejected from the atom; photon scattered with reduction in energy
Binding energy comparatively small and can be ignored
Dowd, S.B. Practical Radiation Protection and Applied Radiobiology
)cos1(1 20
0
0
0
cmE
EE
EEE
sc
esc
As incident photon energy increases, scattered photons and electrons are scattered more toward the forward direction
These photons are much more likely to be detected by the image receptor, reducing image contrast
Probability of interaction increases as incident photon energy increases; probability also depends on electron density Number of electrons/gram fairly constant in tissue;
probability of Compton scatter/unit mass independent of Z
Laws of conservation of energy and momentum place limits on both scattering angle and energy transfer
Maximal energy transfer to the Compton electron occurs with a 180-degree photon backscatter
Scattering angle for ejected electron cannot exceed 90 degrees
Energy of the scattered electron is usually absorbed near the scattering site
Incident photon energy must be substantially greater than the electron’s binding energy before a Compton interaction is likely to take place
Probability of a Compton interaction increases with increasing incident photon energy
Probability also depends on electron density (number of electrons/g density) With exception of hydrogen, total number of
electrons/g fairly constant in tissue Probability of Compton scatter per unit mass nearly
independent of Z
All of the incident photon energy is transferred to an electron, which is ejected from the atom
Kinetic energy of ejected photoelectron (Ec) is equal to incident photon energy (E0) minus the binding energy of the orbital electron (Eb)
Ec = Eo - Eb
Dowd, S.B. Practical Radiation Protection and Applied Radiobiology
Incident photon energy must be greater than or equal to the binding energy of the ejected photon
Atom is ionized, with an inner shell vacancy Electron cascade from outer to inner shells
Characteristic x-rays or Auger electrons Probability of characteristic x-ray emission
decreases as Z decreases Does not occur frequently for diagnostic energy
photon interactions in soft tissue
Probability of photoelectric absorption per unit mass is approximately proportional to
No additional nonprimary photons to degrade the image
Energy dependence explains, in part, why image contrast decreases with higher x-ray energies
33 / EZ
Although probability of photoelectric effect decreases with increasing photon energy, there is an exception
Graph of probability of photoelectric effect, as a function of photon energy, exhibits sharp discontinuities called absorption edges
Photon energy corresponding to an absorption edge is the binding energy of electrons in a particular shell or subshell
At photon energies below 50 keV, photoelectric effect plays an important role in imaging soft tissue
Process can be used to amplify differences in attenuation between tissues with slightly different atomic numbers, improving image contrast
Photoelectric process predominates when lower energy photons interact with high Z materials (screen phosphors, radiographic constrast agents, bone)
Can only occur when the energy of the photon exceeds 1.02 MeV
Photon interacts with electric field of the nucleus; energy transformed into an electron-positron pair
Of no consequence in diagnostic x-ray imaging because of high energies required
Attenuation of gamma –rays in a material is exponential,
I = Io e-µx
Io adalah Intensitas awal I adalah intensitas gamma setelah melalui
material µ adalah koefisien absorption X adalah ketebalan material
X1/2 = 0.693/µ
Counts per minute Curie (unit) , Bq Gray (unit) Rad (unit) Rem (unit) röntgen (unit) Sverdrup (unit) (a unit of volume transport with the same
symbol Sv as Sievert) Background radiation Relative Biological Effectiveness Radiation poisoning Linear Energy Transfer
Counts per minute (cpm) is a measure of radioactivity. It is the number of atoms in a given quantity of radioactive material that are detected to have decayed in one minute.
Disintegrations per minute (dpm) is also a measure of radioactivity. It is the number of atoms in a given quantity of radioactive material that decay in one minute. Dpm is similar to cpm, however the efficiency of the radiation detector
CPM ~ DPM DPM = Ef Det x CPM
One Bq is activity of a quantity of radioactive material in which one nucleus decay per second
SI unit untuk Radioactivity is, Bacquerel = Bq adalah unit terkecil 1 Bq = 1 radioactive decay per second (S-
1)= dis/s 1 Bq = 60 dpm Satuan Lama adalah Curie = Ci , 1 Ci = 3.7 x 1010 Bq = 37 GBq Bq dapat dalam bentuk sbb - kBq , MBq, GBq, TBq and PBq Hitung : 0,25 Ci = ……dpm ?
Pada pengukuran zat radioaktive dgn alat ukur akan terukur unit cps (count per second) or cpm (count per minute) dalam bentuk digital. Konversi cps ke absolute activity (Bq) adalah :
Bq = cps x detektor effesiensi
Unit of absorbed radiation dose (SI) due to ionization radiation (X-ray) is called Gray (Gy)
Absorbed dose (also known as total ionizing dose, TID) is a measure of the energy deposited in a medium by ionizing radiation. It is equal to the energy deposited per unit mass of medium, and so has the unit J/kg, which is given the special name Gray (Gy).
1 Gy of alpha radiation would be much more biologically damaging than 1 Gy of photon radiation
Absorbed dose ; SI , Gray (Gy, kGy, etc)
Definition : One gray is the absorption of one joule of energy, in the form of ionizing radiation, by one kilogram of matter
1 Gy = 1 J/kg
Absorbed dose = Gray (Gy), mengukur deposit energi radiasi
100 rad = 1 Gy
Absorbed dose is the amount of energy absorbed into matter. The working SI unit is a gray (Gy), while the traditional unit is rad (rad)
1 rad = 62.4 x 106 MeV per gram1 gray = 100 erg per gram
1 rad = 0.01 gray1 gray (Gy) = 100 rad
In the United States, radiation absorbed dose, dose equivalent, and exposure are often measured and stated in the older units called rad, rem, or roentgen (R)
Rongent as radiation exposure equal to the ionization radiation will produce one esu of electricity in one cc of dry air at oC and standard atmosfer
1 Gy ≈ 115 R The röntgen was occasionally used to
measure exposure to radiation in other forms than X-rays or gamma rays
1 R = 2.58×10−4 C/kg (from 1 esu ≈ 3.33564 × 10−10 C and the standard atmosphere air density of ~1.293 kg/m³)
The rad (radiation absorbed dose) is a unit of absorbed radiation dose
A dose of 1 rad means the absorption of 100 ergs of radiation energy per gram of absorbing material
1 Gy = 100 rad 1 roentgen (R) = 258 microcoulomb/kg
(µC/kg)
When ionising radiation is used to treat cancer, the doctor will usually prescribe the radiotherapy treatment in Gy. When risk from ionising radiation is being discussed, a related unit, the sievert is used.
The equivalent dose (HT) is a measure of the radiation dose to tissue where an attempt has been made to allow for the different relative biological effects of different types of ionizing radiation
Equivalent dose adalah absorbed dose + biology effect
= Rongent Equivalent Man (REM)
Equivalent dose (HTR) = Absorbed dose (Gy) x radiation weighting factor (Wr)
Equivalent dose (SI) ---- Sievert (Sv) unit Sievert (sv) (biasanya untuk X-ray) 100 REM = 1 Sv 1 Sv = 1 J/kg = Gy
Dose equivalent is the absorbed dose into biological matter taking into account the interaction of the type of radiation and its associated linear energy transfer through specific tissues. The working SI unit is the sievert (Sv), while the traditional unit is roentgen equivalent man (rem).
1Sv = 1 rads x quality factor x any other modifying factors1rem = 1 gray x quality factor x any other modifying factors
1 Sv =100 roentgen equivalent man (rem)1 rem = 0.01Sv = 10mSv
The dose equivalent is a measure of biological effect for whole body irradiation. The dose equivalent is equal to the product of the absorbed dose and the Quality Factor
The millisievert is commonly used to measure the effective dose in diagnostic medical procedures (e.g., X-rays, nuclear medicine, positron emission tomography, and computed tomography). The natural background effective dose rate varies considerably from place to place, but typically is around 2.4 mSv/year
that quantity of X rays which when absorbed will cause the destruction of the [malignant mammalian] cell
This variation in effect is attributed to the Linear Energy Transfer [LET] of the type of radiation, creating a different relative biological effectiveness for each type of radiation under consideration
the RBE [Q] for electron and photon radiation is 1, for neutron radiation it is 10, and for alpha radiation it is 20
unit of the equivalent dose is the rem (Röntgen equivalent man); 1 Sv is equal to 100 rem, for a quality factor Q=1
Here are some quality factor values:[
Photons, all energies : Q = 1 Electrons all energies : Q = 1 Neutrons,
energy < 10 keV : Q = 5 10 keV < energy < 100 keV : Q = 10 100 keV < energy < 2 MeV : Q = 20 2 MeV < energy < 20 MeV : Q = 10 energy > 20 MeV : Q = 5
Protons, energy > 2 MeV : Q = 5 Alpha particles and other atomic nuclei : Q = 20
Dose rate criteria (outside storage area):
2.5 Sv/hr = 0.25mrem/hr CNSC Dose Limits (non-Nuclear Energy
Worker): Whole body = 1mSv/yr = 100 mrem/yr
Skin, Hands, Feet = 50 mSv/yr = 5 rem/yr
Here are some N values for organs and tissues:[2]
Gonads: N = 0.20 Bone marrow, colon, lung, stomach: N =
0.12 Bladder, brain, breast, kidney, liver,
muscles, oesophagus, pancreas, small intestine, spleen, thyroid, uterus: N = 0.05
Bone surface, skin: N = 0.01
And for other organisms, relative to humans: Viruses, bacteria, protozoans: N ≈ 0.03 – 0.0003 Insects: N ≈ 0.1 – 0.002 Molluscs: N ≈ 0.06 – 0.006 Plants: N ≈ 2 – 0.02 Fish: N ≈ 0.75 – 0.03 Amphibians: N ≈ 0.4 – 0.14 Reptiles: N ≈ 1 – 0.075 Birds: N ≈ 0.6 – 0.15 Humans: N = 1
Radiation source Comments mSv/yr mrem/yr
Natural sources
indoor radon due to seepage of 222Rn from ground
2.0 200
radionuclides in body
primarily 40K and 238U progeny
0.39 39
terrestrial radiation
due to gamma-ray emitters in ground
0.28 28
cosmic rays roughly doubles for 2000 m gain in elevation
0.27 27
cosmogenic especially 14C 0.01 1
total (rounded) 3.0 300
Medical sources
Diagnostic x-rays
excludes dental examinations
0.39 39
Medical treatments
radionuclides used in diagnosis (only)
0.14 14
total 0.53 53
Other
consumer products
primarily drinking water, building materials
0.1 10
occupational averaged over entire US population
0.01 1
nuclear fuel cycle
does not include potential reactor accidents
0.0005 0.05
TOTAL (rounded) 3.6 360
Proses Big bang dan pembentukan alam Radioaktive decay untuk dating
(penanggalan) umur batuan (C-14 dan K/Ar) Irradiasi gamma untuk sterilisasi produk
kesehatan dan makanan Reaktor nuklir untuk PLTN Teknik radiotracer untuk Industri Teknik radiasi untuk pertanian Laser dan pemanfaatannya untuk kesehatan
Proses pemisahan (enrichment) bahan bakar U235 dan U238
What is This?
What is This?
What is This?
What is This?
What is This?
What is This?
Where Does This Occur?
Where Does This Occur?
Where Does This Occur?
Where Does This Occur?