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

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