Introduction to Radiation Physics Fundamentals

1- Introduction to Radiation Physics
‫اإلشعاعية‬ ‫الفيزياء‬
Dr. Mohamed Adnan
GULF HOUSE INSTITUTE
‫للتواصل‬
https://twitter.com/ghinstitutesa
http://roadinstitute.edu.sa/pages/Default.aspx

Dr. Mohamed Adnan RSO Training Course Gulf House Institute 2020
Chapter 1. TABLE OF CONTENTS
1.1. Introduction ‫مقدمة‬
1.2. Classification of radiation
‫اإلشعاع‬ ‫تصنيف‬
1.3. Atomic and nuclear structure
‫للمادة‬ ‫والنووي‬ ‫الذري‬ ‫التركيب‬
1.4. X rays ‫األشعة‬
‫السينية‬

Fundamental physical constants
Avogadro’s number NA = 6.022 × 1023
atom/mol
Speed of light in vacuum C = 3x108 m/c
Electron charge e =1.6 x 1019 As
Electron rest mass Me = 0.511 MeV/C2
Proton rest mass Mp = 938.2 MeV/C2
Neutron rest mass Mn = 939.3 MeV/C2
Atomic mass unit U = 931.5 MeV/C2

Physical quantities and units
Physical quantities are characterized by their
numerical value (magnitude) and associated unit.
Symbols for physical quantities are set in italic
type, while symbols for units are set in roman type.
For example:
 m = 21 kg E = 15 MeV

Numerical value and the unit of a physical
quantity must be separated by space.
 For example:
 21 kg and 15 MeV
 The currently used metric system of units is
known as the International system of units or
the SI system.

 The SI International system of units is founded on base units for
seven physical quantities:
 Quantity SI unit
 length meter (m)
 mass m kilogram (kg)
 time t second (s)
 electric current (I) ampere (A)
 temperature (T) Kelvin (K)
 amount of substance mole (mol)
 luminous intensity candela (cd)

1.1 INTRODUCTION
is fundamental to the understanding of the physics of medical imaging and
radiation protection. This, the first chapter of the Handbook, summarises those
aspects of these areas which, being part of the foundation of modern physics,
underpin the remainder of the book
• structure of the atom ‫الذري‬ ‫التركيب‬
• elementary nuclear physics ‫النووية‬ ‫الفيزياء‬
• the nature of electromagnetic radiation
•
‫الكهرومغناطيسية‬ ‫الموجات‬ ‫طبيعة‬
• production of X-rays ‫السينية‬ ‫األشعة‬
Knowledge of the

Basic definitions for atomic structure
 The constituent particles forming an atom are
protons, neutrons and electrons. Protons and neutrons
are known as nucleons and form the nucleus of the atom.

Protons: are particles with a positive charge
and mass of 1 unit of atomic mass.
Neutron: Within the nucleus without charge
Electrons: are negatively charged particles
and mass equal to 1/1840 of atomic mass
unit.

Atomic mass unit: It is defined as one twelfth of
the mass of an atom of carbon-12 .

Atomic number Z : Number of protons and
number of electrons in an atom.
Atomic mass number A :
 Number of nucleons (Z + N) in an atom,
where
• Z is the number of protons (atomic
number) in an atom.
• N is the number of neutrons in an atom.

1.3. ATOMIC AND NUCLEAR STRUCTURE
1.3.1. Basic definitions ‫األساسية‬ ‫التعريفات‬
Most of the mass of the atom is concentrated in the atomic
nucleus which consists of:‫النواة‬ ‫في‬ ‫تتركز‬ ‫الذرة‬ ‫كنلة‬
• Z protons and
• (A – Z) = N neutrons
Z: Atomic number ‫الذري‬ ‫العدد‬
(
‫البروتونات‬ ‫عدد‬
)
A: Atomic mass number ‫الكتلي‬ ‫العدد‬
(
‫الربوتونات‬
+
‫النيترون‬
)
Unified atomic mass unit μ: a unit used for specifying the
masses of atoms ‫هي‬ ‫الذرية‬ ‫الكتلة‬ ‫وحدة‬
1/12
‫الكربون‬ ‫كتلة‬ ‫من‬
-
12
1 μ = 1/12 of the mass of the 12C atom or 931.5 MeV/c2
An atom is composed of a central nucleus surrounded by a cloud of
negatively charged electrons
‫الشحنة‬ ‫سالبة‬ ‫باإللكترونات‬ ‫محاطة‬ ‫نواة‬ ‫من‬ ‫الذرة‬ ‫تتكون‬

1.3.1. Basic definitions
Particle Charge (C) Rest energy
(MeV)
Electron (e) - 1.602×10-19 0.511
Proton (p) +1.602×10-19 938.28
Neutron (n) 0 939.57
Radius of an atom ≈ 0.1 nm
Radius of the nucleus ≈ 10-5 nm
In a non-ionised atom:
‫االلكترونات‬ ‫عدد‬ ‫يساوي‬ ‫البروتونات‬ ‫عدد‬ ‫يكون‬ ‫مؤينة‬ ‫الغير‬ ‫الذرة‬
number of electrons = number of protons

Diagnostic Radiology Physics: a Handbook for Teachers and Students – chapter 1, 13
Protons and neutrons are referred to as nucleons
They are bound in the nucleus with the strong force
‫النو‬ ‫الروابط‬ ‫تسمي‬ ‫جدا‬ ‫قوية‬ ‫بروابط‬ ‫النواة‬ ‫في‬ ‫والنيترونات‬ ‫البروتونات‬ ‫يرتبط‬
‫وية‬
The strong force between two nucleons is a very
short-range force, active only at distances of the
order of a few femtometer (fm). 1 fm = 10-15 m

Cs
137
55
3
/
2
A
0155
.
0
98
.
1
A
+
=
Z
Empirical relation between A and Z
Ra
226
88
Co
60
27
nucleus of Cobalt-60
with 27 protons and
33 neutrons
nucleus of Cesium-137
with 55 protons and
82 neutrons
nucleus of Radium-226
with 88 protons and
138 neutrons
X
A
Z
Chemical
symbol for
the element
Atomic mass
number =
Z+N
Atomic
number
X-A
or
(Co-60)
(Cs-137)
(Ra-226)

Isotopes of a given element have in the nucleus :
‫النيترون‬ ‫عدد‬ ‫في‬ ‫وتختلف‬ ‫البروتونات‬ ‫عدد‬ ‫نفس‬ ‫لها‬ ‫العنصر‬ ‫لنفس‬ ‫النظائر‬
‫ات‬
• same number of protons, but
• different numbers of neutrons
Isotopes of chemical element hydrogen (Z = 1)
Isotopes of chemical element carbon (Z = 6)
ordinary hydrogen
deuterium
tritium
C
C
C
14
6
13
6
12
6
H
H
H
3
1
2
1
1
1

unit
mass
atomic
unified
element
an
of
atoms
the
of
mass
average
=
r
A
Atomic weight Ar is a dimensionless physical quantity
The average is a weighted mean over all the isotopes of the
particular element taking account of their relative abundance
‫الذري‬ ‫الوزن‬
Ar
‫لها‬ ‫أبعاد‬ ‫ال‬ ‫مادية‬ ‫كمية‬ ‫هو‬
‫النس‬ ‫الوفرة‬ ‫مراعاة‬ ‫مع‬ ‫المحدد‬ ‫العنصر‬ ‫نظائر‬ ‫جميع‬ ‫على‬ ‫مرجح‬ ‫متوسط‬ ‫هو‬ ‫المتوسط‬
‫بية‬
Atomic mass M is expressed in unified atomic mass unit
The atomic mass M for a particular isotope is smaller than the
sum of the individual masses of constituent particles because of
the intrinsic energy associated with binding the particles
(nucleons) within the nucleus
‫الذرية‬ ‫الكتلة‬ ‫تكون‬
M
‫المكو‬ ‫للجسيمات‬ ‫الفردية‬ ‫الكتل‬ ‫مجموع‬ ‫من‬ ‫أصغر‬ ‫معين‬ ‫لنظير‬
‫نة‬
‫الجسيمات‬ ‫بربط‬ ‫المرتبطة‬ ‫الجوهرية‬ ‫الطاقة‬ ‫بسبب‬
(
‫النوى‬
)
‫النواة‬ ‫داخل‬

Atomic g-atom (gram-atom) is the number of grams of an
atomic substance that contains a number of atoms exactly
equal to one Avogadro’s constant
(NA = 6.022 × 1023 atoms/g-atom)
‫الذرية‬ ‫المادة‬ ‫جرمات‬ ‫عدد‬ ‫في‬ ‫الموجودة‬ ‫الذرات‬ ‫عدد‬ ‫هو‬ ‫أفوجادرو‬ ‫عدد‬
Atomic weight definition means that Ar grams of each
element contain exactly NA atoms. For a single isotope M
grams contain NA atoms
‫أفوجادرو‬ ‫عدد‬ ‫علي‬ ‫يحتوي‬ ‫الذي‬ ‫عنصر‬ ‫كل‬ ‫من‬ ‫الجرامات‬ ‫عدد‬ ‫أن‬ ‫يعني‬ ‫الذري‬ ‫الوزن‬
.
Example:
• 1 gram-atom of Cobalt- 60 is 59.93 g of Co-60
• 1 gram-atom of Radium-226 is 226.03 g of Ra-226

Molecular g-mole (gram-mole) is defined as the number of grams of a
molecular compound that contains exactly one Avogadro’s constant of
molecules
(NA = 6.022 × 1023 molecule/g-mole)
‫الجزيئات‬ ‫من‬ ‫أفوجادرو‬ ‫عدد‬ ‫يحتوي‬ ‫الذي‬ ‫الجزيئي‬ ‫المركب‬ ‫جرامات‬ ‫عدد‬ ‫هو‬ ‫الجزيئ‬ ‫المول‬
The mass of a molecule is the sum of the masses of the atoms that
make up the molecule
‫الجزيء‬ ‫منها‬ ‫يتكون‬ ‫التي‬ ‫الذرات‬ ‫كتل‬ ‫مجموع‬ ‫هي‬ ‫الجزيء‬ ‫كتلة‬
Example:
• 1 gram-mole of water is ≈18 g of water
• 1 gram-mole of carbon dioxide is ≈ 44 g of carbon dioxide

Note that (Z/ Ar) ≈ 0.5 for all elements, except for hydrogen, for
which (Z/ Ar) = 1. Actually, (Z/Ar) slowly decreases from 0.5 for
low Z elements to 0.4 for high Z elements
NA: Avogadro constant, Z : atomic number
Ar : atomic weight, r : density
Number of atoms per
unit mass of an element:
r
A
am
A
N
N =
Number of electrons per unit
volume of an element:
r
A
am
aV
A
N
Z
ZN
ZN r
r =
=
Number of electrons
per unit mass of an element: A
r
am N
A
Z
ZN =

1.3.2. Atomic structure
Modern quantum mechanical model of the atom is built on the work
of many physicists
The idea of a dense central nucleus surrounded by orbiting electrons
was first proposed by
Ernest Rutherford in 1911
‫تت‬ ‫الذرة‬ ‫كتلة‬ ‫ان‬ ‫قال‬ ‫من‬ ‫أول‬ ‫رزرفود‬ ‫وكان‬ ‫الذرة‬ ‫وصف‬ ‫في‬ ‫بداءت‬ ‫الحديثة‬ ‫الكم‬ ‫ميكانيكا‬
‫في‬ ‫ركز‬
‫اإللكترونات‬ ‫حولها‬ ‫ويدور‬ ‫النواة‬
Rutherford’s atomic model is based on results of the
Geiger- Marsden experiment of 1909 with particles
emitted from Radium C, scattered on thin gold foils with
a thickness of 0.00004 cm
‫شري‬ ‫خالل‬ ‫ألفا‬ ‫جسيمات‬ ‫بإمرار‬ ‫ماردسن‬ ‫تجربة‬ ‫علي‬ ‫إعتمد‬ ‫رزرفورد‬ ‫نموذج‬
‫حة‬
‫الذهب‬ ‫من‬ ‫رقيقة‬

Geiger and Marsden found that:
• more than 99% of the a particles incident on the gold foil were
scattered at scattering angles less than 3o
• roughly 1 in 104 alpha particles was scattered with a scattering
angle exceeding 90o
This finding (1 in 104) was in drastic disagreement with the
theoretical prediction of one in 103500 resulting from Thomson’s
atomic model
positive charge
negative electrons
Thomson atomic model Rutherford atomic model
positive charge
negative electrons

Rutherford proposed that:
• mass and positive charge of the
atom are concentrated in the nucleus
of the size of the order of 10-15 m
‫ال‬ ‫فيها‬ ‫تتركز‬ ‫موجبة‬ ‫شحنة‬ ‫ذات‬ ‫النواة‬ ‫ان‬ ‫رزرفورد‬ ‫إفترض‬
‫كتلة‬
• negatively charged electrons
revolve about the nucleus with a
radius of the order of 10-10 m
‫في‬ ‫وتدور‬ ‫سالبة‬ ‫شحنة‬ ‫ذات‬ ‫اإللكترونات‬ ‫وأن‬
‫النواة‬ ‫حول‬ ‫مدارات‬
positive charge
negative electrons
Rutherford atomic model

The Rutherford atomic model, however, had a
number of unsatisfactory features
For example, it could not explain the observed
emission spectra of the elements
‫ال‬ ‫بعض‬ ‫أطياف‬ ‫تفسر‬ ‫لم‬ ‫ألنها‬ ‫مرضية‬ ‫تكن‬ ‫لم‬ ‫رزرفورد‬ ‫إفترضيات‬
‫عناصر‬
Visible lines of emission spectrum for Hydrogen

In 1913, Niels Bohr elaborated the model of hydrogen atom,
based on four postulates:
• the electron revolves in circular allowed orbit about the proton under the
influence of the Coulomb force of attraction being balanced by the
centripetal force arising from the orbital motion
‫دورانة‬ ‫أثناء‬ ‫طاقة‬ ‫أي‬ ‫يفقد‬ ‫وال‬ ‫الكولومية‬ ‫القوي‬ ‫تأثير‬ ‫تحت‬ ‫محددة‬ ‫دائرية‬ ‫مدارات‬ ‫في‬ ‫اإللكترونات‬ ‫تدور‬
‫اعلي‬ ‫لمدار‬ ‫مداره‬ ‫يترك‬ ‫الطاقة‬ ‫من‬ ‫كاف‬ ‫مقدار‬ ‫الالكترون‬ ‫يكتسب‬ ‫عندما‬
• while in orbit, the electron does not lose any energy in spite of being constantly
accelerated
• the angular momentum of the electron in an allowed orbit is quantized and
only takes values of nћ, where n is an integer and ћ = h/2p, where h is
Planck’s constant
• an atom emits radiation when an electron
makes a transition from an initial orbit with
quantum number ni to a final orbit with
quantum number nf for ni > nf.
ni
nf
Ei
Ef
E = Ei - Ef

Diagram representing Bohr’s model of
the hydrogen atom, in which the
orbiting electron is allowed to be only
in specific orbits of discrete radii
‫لإلكترونات‬ ‫الطاقة‬ ‫مستويات‬ ‫يوضح‬ ‫الرسم‬
proton
M, + e
r
electron
m, - e
F
v
ground state
excited state
Quantization of energy, with n = 1, 2, 3...
2
6
.
13
)
eV
(
n
En −
=

Through the work of Heisenberg, Schrödinger, Dirac, Pauli
and others the theory of quantum mechanics was developed.
In this theory, the electrons occupy individual energy states
defined by four quantum numbers as follows:
‫كم‬ ‫ارقام‬ ‫اربعة‬ ‫تشغل‬ ‫اإللكترونات‬ ‫فإن‬ ‫الكم‬ ‫ميكانيكا‬ ‫لقوانين‬ ‫طبقا‬
• the principal quantum number, n, which can take integer values
and specifies the main energy shell ‫الرئيسي‬ ‫الكم‬ ‫عدد‬
• the azimuthal quantum number, l, which can take integer
values between 0 and n − 1 ‫الفرعي‬ ‫الكم‬ ‫عدد‬
• the magnetic quantum number, m, which can take integer
values between – l and +l ‫المغناطيسي‬ ‫الكم‬ ‫عدد‬
• the spin quantum number, s, which takes values -1/2 or +1/2 and
specifies a component of the spin angular momentum of the
electron ‫المغزلي‬ ‫عددالكم‬

According to the Pauli Exclusion Principle, no two
electrons can occupy the same state and it follows that
the number of electron states that can share the same
principal quantum number n is equal to 2n2
‫وفقا‬
‫لمبداء‬
‫اإلستبعاد‬
‫لباولي‬
‫اليمكن‬
‫إللكترونين‬
‫ان‬
‫يشغال‬
‫نفس‬
‫الحالة‬
The energy levels associated with n = 1, 2, 3 etc.
are known as the K, L, M etc. bands

Zero Valence e-
N
M
K
-13.6
-3.4
-1.51
Hydrogen Z = 1
K series
L series
Energy (eV)
L
Energy (eV)
N
M
L
K
L series
K series
Tungsten Z = 74
Valence e-
Zero
- 11,500
- 69,500
- 2,300
Energy levels for hydrogen and tungsten. Possible
transitions between the various energy levels are shown
with arrows
‫والتنجستين‬ ‫الهيدروجين‬ ‫لذرتي‬ ‫الطاقة‬ ‫مستويات‬

Chose the correct answer
 Known as the atomic number of any atom (element – isotope)?
 1- The number of photons in the atom
 2- The number of neutrons in the atom
 3- The number of protons in the atom
 4- Total number of protons and neutrons In the nucleus
Atom
 1-Positively charged particles in the nucleus of the atom.
 2- Particles circulate around the nucleus in the atom.
 3- The basic construction unit in the article.
 4- particles with no electrical charge and in the nucleus of the
atom.
 5- Atomic substances have the same number of protons

Protons
 4- particles with no electrical charge and in the nucleus of the atom.
neutrons
 4- particles with no electrical charge and in the nucleus of the atom.

 Atomic number
 1 - atoms of a certain element have the same number of
protons but different numbers of neutrons.
 2- The total number of protons and neutrons
inside the nucleus of the atom.
 3 - A general expression that symbolizes any
counterparty to any element.
 4- The number of protons in an atom.
 Known mass number of the atom?
 1- The number of photons in the atom
 2- The number of neutrons in the atom
 3- The number of protons in the atom
 4- Total number of protons and neutrons In the nucleus

 electron
 4- particles with no electrical charge and in the nucleus of
the atom.
 element
 4- particles with no electrical charge and in the nucleus of
the atom.

 According to the Bohr model of the atom
nucleus of an atom, which consists?
 1- The nucleus is made up of protons and
neutrons and orbits around electrons in orbits.
 2- Nucleus by protons, neutrons and electrons.
 3- The nucleus is made up of protons and
electrons and is orbited by neutrons
 According to the Bohr model of atoms,
electrons can move freely within the atom( ).
 According to the Bohr model of the atom when
the electrons are able to change its orbit?

Isotopes, radioisotopes and radionuclide's
Isotopes are atoms of an element
1- It has the same number of protons
2- It has a different number of neutrons.
3 - have the same chemical properties .. Why?
4 - The atomic mass has different ........ Why?
5. They may have different radiological properties.

Thanks

1.2 BASIC DEFINITIONS FOR ATOMIC STRUCTURE
‫الذري‬ ‫التركيب‬
 For all elements the ratio Z/A  0.4-0.5 with 1 notable
exception:
Hydrogen, for which Z/A = 1
 The ratio Z/A gradually decreases with increasing Z:
From ~0.5 for low Z elements
To ~0.4 for high Z elements
 For example:
Z/A = 0.50 for
Z/A = 0.45 for
Z/A = 0.39 for

 Most of the atomic mass is concentrated in the atomic nucleus

‫النواة‬ ‫في‬ ‫الذرة‬ ‫كتلة‬ ‫تتركز‬
 Nucleus consists
Z protons
A - Z neutrons,
where Z = atomic number and A = atomic mass
 Protons and neutrons ‫جدا‬ ‫قوية‬ ‫ربط‬ ‫قوة‬ ‫تحت‬ ‫ويكونو‬ ‫النويدة‬ ‫تسمي‬ ‫والنيترونات‬ ‫البروتونات‬
Commonly called nucleons
Bound to the nucleus with the strong force

 Nuclear physics conventions
Designate a nucleus X as
 For example:
Cobalt-60 nucleus
Z = 27 & A = 60 (i.e. 33 neutrons)
identified as:
 Radium-226
Z = 88 & A = 226 (i.e.138 neutrons)
identified as:
X
A
Z
Co
60
27
Ra
226
88

 Classifications
Isotopes of an element ‫النيترونات‬ ‫عدد‬ ‫في‬ ‫يختلفوا‬ ‫لكن‬ ‫العنصر‬ ‫نفس‬ ‫هي‬ ‫اإليزوتوب‬
Atoms with same Z, but different number of neutrons (and A) e.g.
‘Nuclide’ refers to an atomic species, defined by its makeup of protons, neutrons, and
energy state
‘Isotope’ refers to various atomic forms of a given chemical element
Isobars ‫الكتلي‬ ‫العدد‬ ‫في‬ ‫تتشابهة‬ ‫مختلفة‬ ‫عناصر‬ ‫هي‬ ‫األيزوبار‬
Common atomic mass number A , e.g. 60Co and 60Ni
Isotones ‫النيترونات‬ ‫عدد‬ ‫في‬ ‫تتشابهة‬ ‫مختلفة‬ ‫عناصر‬ ‫هي‬ ‫األيزوتون‬
Common number of neutrons
e.g. 3H (tritium) and 4He
 Isomeric (metastable) state ‫اإلستقرار‬ ‫حالة‬ ‫في‬ ‫يختلفوا‬ ‫لكن‬ ‫العنصر‬ ‫نفس‬ ‫هو‬ ‫األيزومير‬
Excited nuclear state that exists for some time e.g 99mTc is an isomeric
state of 99Tc
Co
59
27 Co
60
27

radionuclide's
 1- The total number of protons and neutrons inside the
nucleus of the atom.
 3 - nuclide launches radiation
 4- A Isotopes that releases radiation.

Isotopes
 1 - atoms of a certain element have the same
number of protons but different numbers of
neutrons.
 2- The total number of protons and neutrons inside
the nucleus of the atom.
 4 - nuclide launches radiation.
 5. A Isotopes that releases radiation.

Hydrogen
isotopes
 Hydrogen is the only
chemical element whose
isotopes are different, since
the isotopes of other
elements are differentiated
by the corresponding mass.
The analog is called
hydrogen-2 deuterium,
while the hydrogen-3
analog is called tritium. The
common analog of
hydrogen, hydrogen-1,
which does not contain
neutrons, is called proteium.

Chemical bonds between
atoms
Most atoms do not exist individually
but are associated with other atoms
in so-called chemical bonds:
Covalent bonds
Ionic bonds

Chemical bonds between atoms

A covalent bond, also called a molecular bond, is a
chemical bond that involves the sharing of electron pairs between
atoms.
 These electron pairs are known as shared pairs or bonding pairs,
and the stable balance of attractive and repulsive forces between
atoms, when they share electrons, is known as covalent bonding

Ionic bonding is the complete transfer of valence
electron(s) between atoms.
It is a type of chemical bond that generates two
oppositely charged ions.

In ionic bonds, the metal loses electrons to become a
positively charged cation, whereas the nonmetal
accepts those electrons to become a negatively
charged anion.

Test Chose the correct answer
 Covalent bond
1-The type of chemical bonds where the
atoms involved in electrons.
2-A group of atoms linked to a
chemical.
3-Element needs to gain electrons to
become chemically stable.
4-The type of chemical bond that is
formed by the attraction between
positive and negative ions

 Ionic bond
 1-The type of chemical bonds where the atoms
involved in electrons.
 2-A group of atoms linked to a chemical.
 3-Element needs to gain electrons to become
chemically stable.
 4-The type of chemical bond that is formed by the
attraction between positive and negative ions

 Positive ion
 1-An element that needs to lose electrons to become chemically
stable.
 2 - atom with a positive charge.
 4-element needs to gain electrons to become chemically stable.
 5-Atoms with negative charge.

 Metals
 1. An element that needs to lose electrons to become chemically
stable.
 4-element needs to gain electrons to become chemically stable.

 The molecule
 1. An element that needs to lose electrons to become chemically
stable.
 3. The type of chemical bonds where the atoms involved in
electrons.
 4. A group of atoms linked to a chemical.

 Non-metals
 1. An element that needs to lose electrons to
become chemically stable.
 4-element needs to gain electrons to become
chemically stable.

 Salt
chemically stable.
 2-The type of chemical bond that is formed by the
attraction between positive and negative ions.
 3-atoms with a negative charge.
 4-The combination of metals and Non- metals.

 Negative ion
 1-An element that needs to lose electrons to become
chemically stable.
chemically stable.
 5-Atoms with negative charge.

Radioisotopes
 1- The total number of protons and neutrons inside the nucleus of
the atom.
 3 - Nuweida launches radiation.
 4. A Isotopes that releases radiation.

Periodic Table
As we mentioned above, the number of protons and
therefore the number of electrons in the atom determines
their chemical properties.
 As the electrons are bound by certain orbits and
encapsulates, the elements with similar numbers of
electrons in their outer shells also exhibit similar
chemical properties.
As we see, the periodic table is divided into eight vertical
columns, and all the elements in the same column have
the same number of electrons in their outer shells and
thus have similar chemical properties.
The periodic table gives the name and symbol of each
element and its number and atomic weight

Periodic Table
For example Ca ,Barium (Ba), Sr and Radium (Ra) are all in
the same column of the periodic table and have similar
chemical properties.
Elements with an atomic number above 92 are artificially
obtained and are radically non-existent in nature, and are
radically important in relation to nuclear facilities.
Because calcium is one of the essential components of human
bone formation, other similar elements are believed to be
human bone-searching, where they will be treated by the body
in the same way as calcium.
This is of radioactive importance where it determines where
the radiation will affect the person exposed to radionuclides
such as radium.

1.1 INTRODUCTION
1.1.4. Classification of ionizing radiation
❑ Ionizing radiation carries enough energy per quantum to remove an
electron from an atom or molecule
❑
‫جزيء‬ ‫أو‬ ‫ذرة‬ ‫من‬ ‫إلكترون‬ ‫إلزالة‬ ‫كم‬ ‫لكل‬ ‫كافية‬ ‫طاقة‬ ‫يحمل‬ ‫المؤين‬ ‫اإلشعاع‬
• Introduces reactive and potentially damaging ion into the environment of the
irradiated medium
•
‫المشعع‬ ‫الوسط‬ ‫بيئة‬ ‫في‬ ‫ًا‬‫ر‬‫ضا‬ ‫يكون‬ ‫أن‬ ‫المحتمل‬ ‫ومن‬ ‫تفاعلي‬ ‫أيون‬ ‫يدخل‬
• Can be categorized into two types: ‫نوعين‬ ‫إلى‬ ‫تصنيفها‬ ‫يمكن‬
:
• Directly ionizing radiation ‫مباشرة‬ ‫مؤين‬ ‫إشعاع‬
• Indirectly ionizing radiation ‫مباشر‬ ‫غير‬ ‫بشكل‬ ‫مؤين‬ ‫إشعاع‬
• Both can traverse human tissue ‫البشرية‬ ‫األنسجة‬ ‫يخترق‬ ‫أن‬ ‫يمكن‬ ‫كالهما‬
• Can be used in medicine for imaging & therapy.
•
‫والعالج‬ ‫للتصوير‬ ‫الطب‬ ‫في‬ ‫استخدامه‬ ‫يمكن‬

Classification of radiation
 Radiation is classified into two main categories:
Non-ionizing radiation .
Ionizing radiation (can ionize matter) -
:
1- Directly ionizing radiation (charged particles)
electron, proton, alpha particle, heavy ion
2- Indirectly ionizing radiation (neutral particles)
photon (x ray, gamma ray), neutron

1.3 Classification of radiation

Classification of ionizing photon radiation
Ionizing photon radiation is classified into four
categories:
Characteristic x ray: Results from electronic
transitions between atomic shells.
Bremsstrahlung : Results mainly from electron-
nucleus Coulomb interactions.
Gamma ray: Results from nuclear transitions.
Annihilation quantum: (annihilation radiation)
 Results from positron-electron annihilation.

1.2. CLASSIFICATION OF RADIATION ‫اإلشعاع‬ ‫تصنيف‬
Radiation may be classified as:‫الي‬ ‫تصنيفه‬ ‫يمكن‬
Electromagnetic radiation
‫الكهرومغناطيسية‬ ‫الموجات‬
Particulate radiation
‫المشعة‬ ‫الجسيمات‬
• radiofrequency ‫الراديو‬ ‫موجات‬
• infrared ‫الحمراء‬ ‫تحت‬ ‫الموجات‬
• visible light ‫المرئي‬ ‫الضوء‬
ultraviolet ‫بنفسيجية‬ ‫الفوق‬
• X rays ‫السينية‬ ‫االشعة‬
• gamma rays ‫جاما‬ ‫اشعة‬
• electrons ‫اإللكترونات‬
• positrons ‫البوزيترونات‬
• protons ‫البروتونات‬
• neutrons ‫النيترونات‬

1.2. CLASSIFICATION OF RADIATION
1.2.1. Electromagnetic radiation‫الكهرومغناطيسية‬ ‫الموجات‬
c
x
y
z
Eo
Bo

c
x
y
z
Eo
Bo

Electromagnetic waves consist of
oscillating electric and magnetic
fields, which are at right angles to
each other and also to the direction
of wave propagation
‫مجالين‬ ‫الكهرومغناطيسيةمن‬ ‫الموجات‬ ‫تتكون‬
‫متعامدين‬ ‫ومغناطيسية‬ ‫كهربي‬
They are characterized by their:
• amplitudes ‫السعة‬ Eo and Bo
• wavelength ‫الموجي‬ ‫الطول‬ ( λ )
• frequency ‫التردد‬ (ν ) and
• speed ‫الموجة‬ ‫سرعة‬ c = λ ν
In vacuum, c = 3×108m/s
For X rays:
‫بالهرتز‬ ‫والتردد‬ ‫بالنانومتر‬ ‫يقاس‬ ‫الموجي‬ ‫الطول‬
• wavelength is usually
expressed in nanometre (nm)
(1 nm = 10-9m) and
• frequency is expressed in hertz (Hz)
(1 Hz = 1 cycle/sec = 1 sec-1)

1.2.1. Electromagnetic radiation
Electromagnetic spectrum as a function of:
‫والتردد‬ ‫الموجي‬ ‫الطول‬ ‫في‬ ‫دالة‬ ‫الكهرومغناطيسية‬ ‫الموجات‬
• wavelength (nm)
• frequency (Hz)
WAVELENGTH (nm)
FREQUENCY (Hz)
1015 1012 109 106 10-6
103 1 10-3
3x102 3x105 3x108 3x1011 3x1014 3x1017 3x1020 3x1023
Radio
Television
Radar
MRI
Infrared
Ultra
violet Gamma rays
X Rays
diagnostic therapeutic
‫التشخيصي‬ ‫العالجي‬

Electromagnetic spectrum as a function of:
• photon energy (eV)
•
‫والطاقة‬ ‫الكهرومغناطيسية‬ ‫الموجات‬ ‫عالقة‬
ENERGY (eV)

1.2 CLASSIFICATION OF RADIATION
When interactions with matter are considered, electromagnetic radiation is
generally treated as series of individual particles, known as photons. The
energy E of each photon is given by:
‫الطاقة‬ ‫عطى‬ُ‫ت‬‫و‬ ،‫فوتونات‬ ‫أنه‬ ‫على‬ ‫المادة‬ ‫مع‬ ‫الكهرومغناطيسي‬ ‫اإلشعاع‬ ‫يتفاعل‬
E
‫بالعالقة‬ ‫فوتون‬ ‫لكل‬
:

/
hc
hv
E =
=
h (Planck’s constant) ‫بالنك‬ ‫=ثابت‬ 6.63×10-34 J∙s = 4.14×10-15 eV∙s
1 eV = 1.6×10-19 J, is the energy given to an electron by
accelerating it through 1 volt of electric potential difference
‫مقداره‬ ‫الكهربائي‬ ‫الجهد‬ ‫فرق‬ ‫خالل‬ ‫مروره‬ ‫عند‬ ‫لإللكترون‬ ‫الممنوحة‬ ‫الطاقة‬ ‫هي‬ ‫فولت‬ ‫اإللكترون‬
1
‫فولت‬
ν (Hz = s-1) is the frequency of electromagnetic wave ‫التردد‬
λ (m) is the wavelength of electromagnetic wave ‫الموجي‬ ‫الطول‬
In diagnostic radiology the photon energy is usually expressed in
units of keV. 1 keV = 1000 Ev
‫بوحدات‬ ‫التشخيصية‬ ‫األشعة‬ ‫في‬ ‫الفوتون‬ ‫طاقة‬ ‫عن‬ ‫التعبير‬ ‫يتم‬ ‫ما‬ ‫عادة‬
keV

1.2.2. Particulate radiation
‫المشعة‬ ‫الجسيمات‬
In diagnostic radiology, the only particulate
radiation that needs to be considered is the
electron
‫في‬
‫األشعة‬
‫التشخيصية‬
‫والعالجية‬
‫بنهتم‬
‫باإللكترون‬
Rest Mass of Electron = 9.109 ×10-31 kg
Rest Energy of Electron = 511 keV = 0.511 MeV

1.2.3. Ionizing and non-ionizing radiation
‫مؤين‬ ‫والغير‬ ‫المؤين‬ ‫اإلشعاع‬
Non-ionizing radiation - cannot ionize matter:
(electromagnetic radiation with energy below the far-
ultraviolet region, e.g. visible light, infrared and
radiofrequency)
‫تفقد‬ ‫المادة‬ ‫الطاقةلجعل‬ ‫من‬ ‫الكاف‬ ‫المقدار‬ ‫عندها‬ ‫ليس‬ ‫مؤين‬ ‫الغير‬ ‫اإلشعاع‬
‫احد‬
‫المرئ‬ ‫والضوء‬ ‫حمراء‬ ‫التحت‬ ‫االشعة‬ ‫مثل‬ ‫الكتروناتها‬
Ionizing radiation - can ionize matter: (fast charged
particles, X rays, gamma rays and neutrons)
‫اشعة‬ ‫مثل‬ ‫المادة‬ ‫تأيين‬ ‫علي‬ ‫المقدره‬ ‫عنده‬ ‫الذي‬ ‫هو‬ ‫المؤين‬ ‫اإلشعاع‬
‫والنيترونات‬ ‫والسينية‬ ‫جاما‬

Ionizing radiation - can ionize matter either:
Directly : ‫المباشر‬
fast charged particles that
deposit their energy in matter
directly, through many small
Coulomb (electrostatic)
interactions with orbital
electrons along the particle
track
‫المادة‬ ‫في‬ ‫طاقتها‬ ‫تودع‬ ‫مشحونة‬ ‫جسيمات‬
‫كول‬ ‫تفاعالت‬ ‫من‬ ‫العديد‬ ‫خالل‬ ‫من‬ ، ‫مباشرة‬
‫وم‬
‫الصغيرة‬
(
‫اإللكتروستاتيكية‬
)
‫اإلل‬ ‫مع‬
‫كترونات‬
‫الجسيمات‬ ‫مسار‬ ‫طول‬ ‫على‬ ‫المدارية‬
Indirectly: ‫مباشر‬ ‫الغير‬
X- or gamma- ray photons or neutrons
that first transfer their energy to fast
charged particles released in one or a
few interactions in the matter through
which they pass. The resulting fast
charged particles then deposit their
energy directly in the matter
‫تنق‬ ‫شحنة‬ ‫لها‬ ‫ليس‬ ‫التي‬ ‫الجسيمات‬ ‫أو‬ ‫فوتونات‬
‫ل‬
‫تنطلق‬ ‫الشحن‬ ‫سريعة‬ ‫جسيمات‬ ‫إلى‬ ً‫ال‬‫أو‬ ‫طاقتها‬
‫في‬
‫خاللها‬ ‫من‬ ‫تمر‬ ‫التي‬ ‫المادة‬
.
‫الجسيمات‬ ‫تقوم‬ ‫ثم‬
‫مباشرة‬ ‫طاقتها‬ ‫بإيداع‬ ‫الناتجة‬ ‫بسرعة‬ ‫المشحونة‬
‫في‬
‫المادة‬

Ionization potential is the minimum energy required to ionize
an atom. For elements its magnitude ranges from a few eV for
alkali metals to 24.5 eV for helium. For water it is 12.6 eV
‫الذرة‬ ‫لتأين‬ ‫المطلوبة‬ ‫الطاقة‬ ‫من‬ ‫األدنى‬ ‫الحد‬ ‫هو‬ ‫التأين‬ ‫جهد‬
Element Ionization potential (eV)
H 13.6
C 11.3
O 13.6
Mo 7.1
W 7.9

INTRODUCTION
1.1.5. Classification of indirectly ionizing photon radiation
‫مباشر‬ ‫غير‬ ‫بشكل‬ ‫المؤين‬ ‫الفوتون‬ ‫إشعاع‬ ‫تصنيف‬
❑ Consists of three main categories: ‫رئيسية‬ ‫فئات‬ ‫ثالث‬ ‫من‬ ‫تتكون‬
:
• Ultraviolet: limited use in medicine ‫البنفسجية‬ ‫فوق‬ ‫األشعة‬
:
‫الطب‬ ‫في‬ ‫محدود‬ ‫استخدام‬
• X ray: used in disease imaging and/or treatment Emitted by orbital or accelerated electrons
•
‫السينية‬ ‫األشعة‬
:
‫االلكترونات‬ ‫تعجيل‬ ‫او‬ ‫المدارات‬ ‫من‬ ‫تنتج‬ ‫العالجي‬ ‫أو‬ ‫الطبي‬ ‫التصوير‬ ‫في‬ ‫تستخدم‬
•  ray: used in disease imaging and/or treatment
• Emitted by the nucleus or particle decays
•
‫جاما‬ ‫أشعة‬
:
‫الجسيمات‬ ‫تحلل‬ ‫أو‬ ‫النواة‬ ‫من‬ ‫تنبعث‬ ‫العالجي‬ ‫أو‬ ‫الطبي‬ ‫التصوير‬ ‫في‬ ‫تستخدم‬
• Difference between X and  rays is based on the radiation’s origin
•
‫اإلشعاع‬ ‫منشأ‬ ‫على‬ ‫جاما‬ ‫واشعة‬ ‫السينية‬ ‫األشعة‬ ‫بين‬ ‫الفرق‬ ‫يعتمد‬
❑ The origin of these photons fall into 4 categories:
• Characteristic (fluorescence) X rays ‫المميزة‬ ‫السينية‬ ‫االشعة‬
(
‫الوميضية‬
)
• Bremsstrahlung X rays ‫االنكباحية‬ ‫السينية‬ ‫االشعة‬
• From nuclear transitions ‫النووي‬ ‫اإلضمحالل‬ ‫من‬ ‫الناتجة‬ ‫جاما‬ ‫أشعة‬
• Annihilation quanta ‫اإللكترونات‬ ‫إبادة‬ ‫من‬ ‫الناتجة‬ ‫جاما‬ ‫أشعة‬

1.1 INTRODUCTION
1.1.6. Characteristic X rays ‫المميزة‬ ‫السينية‬ ‫األشعة‬
❑ Orbital electrons inhabit atom’s minimal energy state
❑
‫الطاقة‬ ‫في‬ ‫أقل‬ ‫مدار‬ ‫إل‬ ‫اإللكترون‬ ‫إنتقال‬
❑ An ionization or excitation process leads to an open vacancy
❑
‫المدار‬ ‫في‬ ‫فراغ‬ ‫وجود‬ ‫الي‬ ‫تؤدي‬ ‫اإلثارة‬ ‫أو‬ ‫التأين‬ ‫عملية‬ ‫ان‬ ‫حيث‬
❑ An outer shell electron transitions to fill vacancy (~nsec)
❑
‫خارجي‬ ‫مدار‬ ‫من‬ ‫بإلكترون‬ ‫الفراغ‬ ‫هذا‬ ‫يعوض‬ ‫وبالتالي‬
❑ Liberated energy may be in the form of: ‫صورة‬ ‫في‬ ‫الطاقة‬ ‫من‬ ‫مقدار‬ ‫اإللكترون‬ ‫هذا‬ ‫يفقد‬ ‫بالتالي‬
‫فوتون‬
• Characteristic photon (fluorescence) ‫المميزة‬ ‫األشعة‬
(
‫الوميضية‬
)
• Energy = initial state binding energy - final state binding energy
•
‫الناتج‬ ‫الفوتون‬ ‫طاقة‬
=
‫األساسي‬ ‫بالمدار‬ ‫الربط‬ ‫طاقة‬
–
‫النهائي‬ ‫بالمدار‬ ‫الربط‬ ‫طاقة‬
• Photon energy is characteristic of the atom ‫الذرة‬ ‫تميز‬ ‫هذه‬ ‫الفتون‬ ‫وطاقة‬
• Transferred to orbital electron that
• Emitted with kinetic energy = transition energy - binding energy
• Called an Auger electron
•
‫حركة‬ ‫بطاقة‬ ‫أوجيور‬ ‫إلكترون‬ ‫يسمي‬ ‫مداري‬ ‫إلكترون‬ ‫الي‬ ‫الطاقة‬ ‫تنقل‬
=
‫اإلنتقالية‬ ‫الطاقة‬
–
‫الربط‬ ‫طاقة‬

1.1 INTRODUCTION
1.1.7. Bremsstrahlung ‫اإلنكباحية‬ ‫األشعة‬
❑ Translated from German as 'breaking radiation'
❑ Light charged particles (b- & b+) slowed down by interactions with other charged
particles in matter (e.g. atomic nuclei)
❑
‫ا‬ ‫من‬ ‫بالقرب‬ ‫مرورها‬ ‫عند‬ ‫السالبة‬ ‫او‬ ‫الموجبة‬ ‫بيتا‬ ‫جسيمات‬ ‫تباطؤ‬ ‫نتيجة‬ ‫اإلنكباحية‬ ‫األشعة‬ ‫تنتج‬
‫الذرية‬ ‫لنويات‬
❑ Kinetic energy loss converted to electromagnetic radiation
❑
‫ا‬ ‫الصفر‬ ‫من‬ ‫يبداء‬ ‫مستمر‬ ‫طيف‬ ‫ذو‬ ‫ويكون‬ ‫كهرومغناطيسي‬ ‫إشعاع‬ ‫إلي‬ ‫الحركة‬ ‫طاقة‬ ‫تتحول‬ ‫حيث‬
‫طاقة‬ ‫لي‬
‫األولي‬ ‫المشحون‬ ‫الجسيم‬
❑ Bremsstrahlung energy spectrum
• Non-discrete (i.e. continuous)
• Ranges: zero - kinetic energy of initial charged particle
❑ Central to modern imaging and therapeutic technology
• Can be used to produce X rays from an electrical energy source
•
‫كهربائية‬ ‫طاقة‬ ‫مصدر‬ ‫من‬ ‫السينية‬ ‫األشعة‬ ‫إلنتاج‬ ‫استخدامه‬ ‫يمكن‬

1.1 INTRODUCTION
1.1.8. Gamma rays ‫جاما‬ ‫أشعة‬
 Nuclear reaction or spontaneous nuclear decay may leave product (daughter)
nucleus in excited state

‫جا‬ ‫أشعة‬ ‫النواة‬ ‫تفقد‬ ‫حيث‬ ‫النووي‬ ‫اإلضمحالل‬ ‫او‬ ‫النووية‬ ‫للتفاعالت‬ ‫نتيجة‬ ‫جاما‬ ‫أشعة‬ ‫تنتج‬
‫اكثر‬ ‫لتصبح‬ ‫ما‬
‫استقرارا‬
,
‫اكبر‬ ‫تكون‬ ‫وطاقتها‬ ‫للعنصر‬ ‫مميز‬ ‫جاما‬ ‫إضمحالل‬
100
‫فولت‬ ‫إلكترون‬ ‫كيلو‬
 The nucleus can transition to a more stable state by emitting a  ray
 Emitted photon energy is characteristic of nuclear energy transition
  ray energy typically > 100 keV & wavelengths < 0.1 Å

1.1 INTRODUCTION
1.1.9. Annihilation quanta ‫البوزيترون‬ ‫تالشي‬ ‫طريق‬ ‫عن‬ ‫جاما‬ ‫أشعة‬ ‫إنتاج‬
 Positron results from:
• b+ nuclear decay
• high energy photon interacts with nucleus or orbital electron electric field
•
‫األزواج‬ ‫إنتاج‬ ‫من‬ ‫أو‬ ‫النووي‬ ‫اإلضمحالل‬ ‫من‬ ‫ينتج‬ ‫البوزيترون‬
 Positron kinetic energy (EK) loss in absorber medium by Coulomb interactions:
 Collisional loss when interaction is with orbital electron
 Radiation loss (bremsstrahlung) when interaction is with the nucleus
 Final collision (after all EK lost) with orbital electron (due to Coulomb attraction)
called positron annihilation

‫كوليمية‬ ‫بتفاعالت‬ ‫اإللكترون‬ ‫من‬ ‫لتفاعله‬ ‫نتيجة‬ ‫حركتة‬ ‫طاقة‬ ‫البوزيترون‬ ‫يفقد‬
:
-

1
-
‫مداري‬ ‫الكترون‬ ‫مع‬ ‫التصادم‬ ‫عند‬

2
-
‫النواة‬ ‫مع‬ ‫التصادم‬ ‫عند‬ ‫إنكباحية‬ ‫أشعة‬ ‫صورة‬ ‫في‬ ‫يفقد‬

3
-
‫جاما‬ ‫أشعة‬ ‫وينتج‬ ‫للبوزيترون‬ ‫تالشي‬ ‫يحدث‬ ‫المداري‬ ‫الكترون‬ ‫مع‬ ‫النهائية‬ ‫التصادمات‬

1.1 INTRODUCTION
1.1.9. Annihilation quanta ‫البوزيترون‬ ‫تالشي‬ ‫طريق‬ ‫عن‬ ‫جاما‬ ‫أشعة‬ ‫إنتاج‬
 During annihilation ‫التالشي‬ ‫عملية‬ ‫أثناء‬
 Positron & electron disappear
 Replaced by 2 oppositely directed annihilation quanta (photons)
 Each has energy = 0.511 MeV
 Conservation laws obeyed:
 Electric charge, linear momentum, angular momentum, total energy

‫طاقة‬ ‫منهم‬ ‫ولكل‬ ‫واإللكترون‬ ‫البوزيترون‬ ‫يختفي‬
0.511
‫الفوتون‬ ‫وينتج‬ ‫فولت‬ ‫الكترون‬ ‫ميجا‬
 In-flight annihilation
 Annihilation can occur while positron still has kinetic energy
 2 quanta emitted
 Not of identical energies
 Do not necessarily move at 180º

Thanks

2- Introduction to Radiation Physics
X rays and Auger electrons
‫إجيور‬ ‫وإلكترون‬ ‫السينية‬ ‫األشعة‬
Dr. Mohamed Adnan
‫للتواصل‬
https://twitter.com/ghinstitutesa
http://roadinstitute.edu.sa/pages/Default.aspx

Dr. Mohamed Adnan RSO Training Course Gulf House Institute
2020
1.4. X RAYS
1.4.1. The production of characteristic X rays and Auger electrons
‫إلكترون‬ ‫وأجوير‬ ‫السينية‬ ‫األشعة‬ ‫إنتاج‬
When charged particles pass through matter they interact with the
atomic electrons and lose energy through the processes of ionization
and excitation
‫التأين‬ ‫عملية‬ ‫لتنتج‬ ‫طاقتها‬ ‫بعض‬ ‫تفقد‬ ‫المادة‬ ‫خالل‬ ‫المشحونة‬ ‫الجسيمات‬ ‫مرور‬ ‫عند‬
ionization
Atom of Na
K
L
M
ground state
K
L
M
K
L
M
ionization
K
L
M

2020
If the transferred energy exceeds the
binding energy of the electron,
ionization occurs, resulting in the
electron ejected from the atom. An ion
pair consisting of the ejected electron
and the ionized, positively charged atom
is then formed
، ‫اإللكترون‬ ‫ربط‬ ‫طاقة‬ ‫المنقولة‬ ‫الطاقة‬ ‫تجاوزت‬ ‫إذا‬
‫من‬ ‫اإللكترون‬ ‫إخراج‬ ‫إلى‬ ‫يؤدي‬ ‫مما‬ ، ‫التأين‬ ‫يحدث‬
‫الذرة‬
.
‫اإللك‬ ‫من‬ ‫يتكون‬ ‫أيوني‬ ‫زوج‬ ‫تشكيل‬ ‫يتم‬ ‫ثم‬
‫ترون‬
‫الشحنة‬ ‫والموجبة‬ ‫المتأينة‬ ‫والذرة‬ ‫المقذوف‬
The average energy required to produce
an ion pair in air or soft tissue for
electrons is equal to 33.97 Ev
‫الهواء‬ ‫في‬ ‫أيوني‬ ‫زوج‬ ‫إلنتاج‬ ‫الالزمة‬ ‫الطاقة‬ ‫متوسط‬
‫أو‬
‫يساوي‬ ‫لإللكترونات‬ ‫الرخوة‬ ‫األنسجة‬
33.97
‫فولت‬
K
L
M
K
L
M
ejected electron
positive ion
ion pair
ion pair
1.4. X RAYS

2020
When charged particles pass through matter they interact with the atomic
electrons and lose energy through the processes of ionization and excitation
‫من‬ ‫الطاقة‬ ‫وتفقد‬ ‫الذرية‬ ‫اإللكترونات‬ ‫مع‬ ‫تتفاعل‬ ‫فإنها‬ ، ‫المادة‬ ‫عبر‬ ‫المشحونة‬ ‫الجسيمات‬ ‫تمر‬ ‫عندما‬
‫خالل‬
‫واإلثارة‬ ‫التأين‬ ‫عمليات‬
1.4. X RAYS
K
L
M
Atom of Na
ground state
excited state
excitation
K
L
M
de-excitation
E = hn = Ei - Ef
K
L
M
E = hn

2020
Whenever a vacancy is created in an inner electronic
shell, it is filled by an electron from a more distant (outer)
shell
‫خارجي‬ ‫بإلكترون‬ ‫داخلي‬ ‫إلكترون‬ ‫خروج‬ ‫نتيجة‬ ‫الفراغات‬ ‫ملء‬ ‫يتم‬
This results in a vacancy in this second outer shell which
is then filled by an electron (if available) from an even
more distant outer shell and the whole process repeats
producing a cascade of transitions
‫ذلك‬ ‫بعد‬ ‫ملؤه‬ ‫يتم‬ ‫الذي‬ ‫الثاني‬ ‫الخارجي‬ ‫الغالف‬ ‫في‬ ‫شاغر‬ ‫هذا‬ ‫عن‬ ‫وينتج‬
‫بواسطة‬
‫إلكترون‬
(
‫وجد‬ ‫إن‬
)
‫مم‬ ‫بأكملها‬ ‫العملية‬ ‫وتكرر‬ ‫ًا‬‫د‬‫بع‬ ‫أكثر‬ ‫خارجي‬ ‫غالف‬ ‫من‬
‫ينتج‬ ‫ا‬
‫التحوالت‬ ‫من‬ ‫سلسلة‬
1.4. X RAYS

2020
The energy released in each transition is carried away by: the
emission of electromagnetic radiation
•
‫تحمل‬ ‫انتقالية‬ ‫مرحلة‬ ‫كل‬ ‫في‬ ‫المنبعثة‬ ‫الطاقة‬
:
‫الكهرومغناطيسي‬ ‫اإلشعاع‬ ‫انبعاث‬
depending on the atomic number of the material, and the electronic shells
involved, this radiation may be in the visible, ultraviolet, and X ray
portions of the spectrum
‫األ‬ ‫في‬ ‫اإلشعاع‬ ‫هذا‬ ‫يكون‬ ‫قد‬ ، ‫المعنية‬ ‫اإللكترونية‬ ‫والمدارات‬ ، ‫للمادة‬ ‫الذري‬ ‫العدد‬ ‫على‬ ‫ًا‬‫د‬‫اعتما‬
‫جزاء‬
‫الطيف‬ ‫من‬ ‫السينية‬ ‫واألشعة‬ ‫البنفسجية‬ ‫فوق‬ ‫واألشعة‬ ‫المرئية‬
in case of X rays, they are known as
characteristic or fluorescent X rays
1.4. X RAYS
• an electron ejected from another outer shell,
known as Auger electron
‫أجوير‬ ‫إلكترون‬ ‫يسمي‬ ‫الذرة‬ ‫يترك‬ ‫الذي‬ ‫اإللكترون‬

1.4. X RAYS
1.4.1. The production of characteristic X
rays
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
K
M
L
Ka
K
M
L
Ka
K
M
L
Ka
K
M
L Kb
K
M
L Kb
K
M
L Kb
K
M
L
K
M
L
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
8 10
o de onda (10-11
m)
5 kV
Ka
alvo de W
alvo de Mo
K
M
L
Ka
K
M
L
Ka
K
M
L
Ka
K
M
L Kb
K
M
L Kb
K
M
L Kb
K
M
L
Ka
K
M
L
Ka
K
M
L
Ka
K
M
L
Ka
K
M
L
Ka
K
M
L
Ka
K
M
L Kb
K
M
L Kb
K
M
L Kb
K
M
L
K
M
L
• Kα X ray is emitted for
a
transition between
L and K shells
• Kβ X ray is emitted for
a
transition between
M or N and K shells

2020
For tungsten (W):
the energies of the Kα and Kβ characteristic X
rays
are given by:
E (Kα1) = ELIII - EK = - 10.2 - (- 69.5) = 59.3 keV
E (Kα2) = ELI - EK = - 11.5- (- 69.5) = 58.0 keV
E (Kβ1) = EMIII - EK = - 2.3 - (- 69.5) = 67.2 keV
E (Kβ2) = ENIII- EK = - 0.4 - (- 69.5) = 69.1 keV
1.4. X RAYS
1.4.1. The production of characteristic X rays

2020
For molybdenum (Mo):
Energies of K, L and M shell
are:
EK = - 20.0 keV
EL = - 2.6 keV
EM = - 0.4 keV
the energies of the Kα and Kβ
characteristic X rays are
given by:
E (Kα) = EL - EK = - 2.6 - (- 20.0) = 17.4 keV
E (Kβ) = EM - EK = - 0.4 - (- 20.0) = 19.6
keV
1.4. X RAYS
1.4.1. The production of characteristic X rays
cascading
electron
K L M
-20 keV
-2.6 keV
-0.4 keV -
-
- -
-
19.6 keV Kb
Characteristic
X ray
vacant
-
Molybdenum
atom

2020
1.4. X RAYS
1.4.1. The production of Auger electrons
If the initial transition is from an M to a K
shell, and the Auger electron is also emitted
from the M shell, there will be two resultant
vacancies in the M shell
‫إذا‬
‫كان‬
‫االنتقال‬
‫األولي‬
‫من‬
‫قشرة‬
M
‫إلى‬
‫قشرة‬
K
،
‫وانبعاث‬
Auger
‫ًا‬‫ض‬‫أي‬
‫من‬
‫قشرة‬
M
،
‫فسيكون‬
‫هناك‬
‫شاغران‬
‫ناتجان‬
‫في‬
‫قشرة‬
M
The kinetic energy of the Auger electron is
thus determined by the difference between the
binding energy of the shell with the initial
vacancy and the sum of the binding energies
associated with the two vacancies which are
created. In case of molybdenum atom, the
energy of the Auger electron is given by:
‫وهكذا‬
‫يتم‬
‫تحديد‬
‫الطاقة‬
‫الحركية‬
‫إللكترون‬
‫أوجير‬
‫من‬
‫خالل‬
‫الفرق‬
‫بين‬
‫طاقة‬
‫ربط‬
‫القشرة‬
‫مع‬
‫الشغور‬
‫األولي‬
‫ومجموع‬
‫طا‬
‫قات‬
‫الربط‬
‫المرتبطة‬
‫بالشواغرين‬
‫اللذين‬
‫يتم‬
‫إنشاؤهما‬
.
‫في‬
‫حا‬
‫لة‬
‫ذرة‬
‫الموليبدينوم‬
،
‫يتم‬
‫إعطاء‬
‫طاقة‬
‫أوجير‬
‫من‬
‫خالل‬
:
E (Auger) = EM + EM - EK = - 0.4 - 0.4 - (- 20.0) = 19.2 keV
cascading
electron
K L M
-20 keV
-2.6 keV
-0.4 keV -
-
- - -
-
19.2 keV
Auger
electron
vacant
Molybdenum
atom

2020
Auger electron emission is more important for materials of low atomic
number and for transitions amongst outer shells
‫يعد‬
‫انبعاث‬
‫أوجير‬
‫أكثر‬
‫أهمية‬
‫للمواد‬
‫ذات‬
‫العدد‬
‫الذري‬
‫المنخفض‬
‫وللتحوالت‬
‫بين‬
‫المدارات‬
‫الخارجية‬
The K-fluorescence yield is close to zero for low atomic number materials,
but increases with atomic number and is 0.007, 0.17, 0.60 and 0.93 for
oxygen, calcium, selenium and gadolinium respectively
‫إنتاجية‬
‫الفلورة‬
K
‫قريبة‬
‫من‬
‫الصفر‬
‫للمواد‬
‫ذات‬
‫العدد‬
‫الذري‬
‫المنخفض‬
،
‫لكنها‬
‫تزداد‬
‫مع‬
‫العدد‬
‫الذري‬
‫و‬
‫هي‬
0.007
‫و‬
0.17
‫و‬
0.60
‫و‬
0.93
‫لألكسجين‬
‫والكالسيوم‬
‫والسيلينيوم‬
‫والجادولينيوم‬
‫على‬
‫التوالي‬
When considering energy deposition in matter it is important to know
whether a fluorescent X ray or an Auger electron is emitted
‫إ‬ ‫أو‬ ‫الفلورية‬ ‫السينية‬ ‫األشعة‬ ‫كانت‬ ‫إذا‬ ‫ما‬ ‫معرفة‬ ‫المهم‬ ‫من‬ ، ‫المادة‬ ‫في‬ ‫الطاقة‬ ‫ترسب‬ ‫في‬ ‫النظر‬ ‫عند‬
‫لكترون‬
‫تنبعث‬ ‫أوجيه‬
The probability of emission of a fluorescent X ray is known as the
fluorescent yield, denoted ω and the probability of emitting an Auger
electron is 1- ω
،‫إليه‬ ‫المشار‬ ، ‫الفلوري‬ ‫بالعائد‬ ‫الفلورية‬ ‫السينية‬ ‫األشعة‬ ‫انبعاث‬ ‫احتمال‬ ‫ُعرف‬‫ي‬
‫انب‬ ‫واحتمال‬
‫أوجيه‬ ‫إلكترون‬ ‫عاث‬
‫هو‬
1.4. X RAYS

2020
1.4. X RAYS
1.4.2. Radiation from an accelerated charge, Bremsstrahlung
In inelastic interactions of the fast electrons with atomic nuclei as they
pass through matter, the electron path is deflected and energy is
transferred to a photon, which is emitted
‫الم‬ ‫عبر‬ ‫مرورها‬ ‫أثناء‬ ‫الذرية‬ ‫النوى‬ ‫مع‬ ‫السريعة‬ ‫لإللكترونات‬ ‫المرنة‬ ‫غير‬ ‫التفاعالت‬ ‫في‬
‫ينحرف‬ ، ‫ادة‬
‫منه‬ ‫ينبعث‬ ‫الذي‬ ‫الفوتون‬ ‫إلى‬ ‫الطاقة‬ ‫نقل‬ ‫ويتم‬ ‫اإللكترون‬ ‫مسار‬
The emitted photon is known as
Bremsstrahlung, which means
“brake radiation”, in German
‫اإلنكباحية‬ ‫السينية‬ ‫األشعة‬ ‫تنبعث‬
The energy of the emitted photon can
take any value from zero up to the
energy of the initial electron,
producing a continuous spectrum
‫من‬ ‫قيمة‬ ‫أي‬ ‫المنبعث‬ ‫الفوتون‬ ‫طاقة‬ ‫تأخذ‬ ‫أن‬ ‫يمكن‬
‫طي‬ ‫ينتج‬ ‫مما‬ ، ‫األولي‬ ‫اإللكترون‬ ‫طاقة‬ ‫إلى‬ ‫الصفر‬
‫ا‬ً‫ف‬
‫ا‬ً‫مستمر‬
Bremsstrahlung photons are the major
component of the X ray spectrum emitted by
X ray tubes
‫في‬ ‫الرئيسي‬ ‫العنصر‬ ‫هي‬ ‫اإلنكباحية‬ ‫السينية‬ ‫األشعة‬
‫طيف‬
‫السينية‬ ‫األشعة‬ ‫أنابيب‬ ‫من‬ ‫المنبعثة‬ ‫السينية‬ ‫األشعة‬
elétron
energético
elétron menos energético
raio X de
freamento
elétron
energético
elétron menos energético
raio X de
freamento

2020
The angle of emission of the Bremsstrahlung photons depends upon
the electron energy:
‫تعتمد‬
‫زاوية‬
‫انبعاث‬
‫فوتونات‬
‫األشعة‬
‫اإلنكباحية‬
‫على‬
‫طاقة‬
‫اإللكترون‬
• for electron energies much greater than the rest energy of the
electron, the angular distribution is peaked in the forward direction
•
‫بالنسبة‬
‫لإلكترون‬
‫ذو‬
‫الطاقاة‬
‫العالية‬
‫اكبر‬
‫من‬
‫طاقة‬
‫ربط‬
،
‫يتم‬
‫توزيع‬
‫التو‬
‫زيع‬
‫الزاوي‬
‫في‬
‫االتجاه‬
‫األمامي‬
• when the electron energy is low, the radiation is mainly emitted
between 60 and 90 degrees to the forward direction.
•
‫عندما‬
‫تكون‬
‫طاقة‬
‫منخفضة‬
،
‫ينبعث‬
‫اإلشعاع‬
‫بشكل‬
‫رئيسي‬
‫بين‬
‫زاويتي‬
60
‫و‬
90
‫درجة‬
‫إلى‬
‫االتجاه‬
‫األمامي‬
The probability of Bremsstrahlung emission is proportional to Z2. But
even for tungsten (Z = 74) the efficiency of Bremsstrahlung
production is less than 1% for 100 keV electrons
‫مع‬ ‫يتناسب‬ ‫اإلنكباحية‬ ‫األشعة‬ ‫انبعاث‬ ‫احتمال‬
Z2.
‫للتنغستن‬ ‫بالنسبة‬ ‫حتى‬ ‫ولكن‬
(
Z = 74
‫فإن‬
‫اإلنكباحية‬ ‫األشعة‬ ‫إنتاج‬ ‫كفاءة‬
‫من‬ ‫أقل‬
1
‫لإللكترونات‬ ٪
100
‫فولت‬ ‫كيلو‬
1.4.2. Radiation from an accelerated charge, Bremsstrahlung
‫الشحنات‬ ‫تعجيل‬ ‫نتيجة‬ ‫اإلنكباحية‬ ‫األشعة‬

1.1 INTRODUCTION
1.1.10. Radiation quantities and units ‫اإلشعاع‬ ‫ووحدات‬ ‫كميات‬
❑ Exposure: X ‫التعرض‬
• Ability of photons to ionize air ‫الهواء‬ ‫تأيين‬ ‫علي‬ ‫الفوتون‬ ‫قدرة‬
❑ Kerma: K (acronym for Kinetic Energy Released in MAtter)
❑
‫الكيرما‬
:
‫المادة‬ ‫من‬ ‫الكتلة‬ ‫وحدة‬ ‫في‬ ‫المنقولة‬ ‫الطاقة‬ ‫وهي‬ ‫المادة‬ ‫في‬ ‫المودعة‬ ‫الحركة‬ ‫الطاقة‬ ‫هي‬
‫مباشرة‬ ‫الغير‬ ‫المؤينة‬ ‫االشعة‬ ‫من‬ ‫الممتصة‬
• Energy transferred to charged particles per unit mass of the absorber
• Defined for indirectly ionizing radiation
❑ Dose (also referred to as absorbed dose):
• Energy absorbed per unit mass of medium

‫الجرعة‬
(
‫الممتصة‬ ‫بالجرعة‬ ‫ا‬ً‫ض‬‫أي‬ ‫إليها‬ ‫يشار‬
:)
‫الوس‬ ‫من‬ ‫كتلة‬ ‫وحدة‬ ‫لكل‬ ‫الممتصة‬ ‫الطاقة‬ ‫وهي‬
‫ط‬

1.1 INTRODUCTION
❑ Equivalent dose: 𝐻T
• Dose multiplied by radiation weighting factor wR
• When different types of radiation are present, 𝐻T is the sum of all of the individual weighted
contributions
•
‫اإلشعاع‬ ‫معامل‬ ‫في‬ ‫الجرعة‬ ‫مضروب‬ ‫وهي‬ ‫المكافئة‬ ‫الجرعة‬
(
20
‫ألفا‬ ‫لجسيمات‬
–
1
‫وااللكترونات‬ ‫وجاما‬ ‫اكس‬ ‫ألشعة‬
)
❑ Effective dose: E
• 𝐻𝑇 multiplied by a tissue weighting factor wT
•
‫للنسيج‬ ‫الوزي‬ ‫المعامل‬ ‫في‬ ‫المكافئة‬ ‫الجرعة‬ ‫مضروب‬ ‫وهي‬ ‫الفعالة‬ ‫الجرعه‬
❑ Activity: A ‫االشعاعية‬ ‫الشدة‬
:
‫الكيوري‬ ‫او‬ ‫بالبيكرل‬ ‫وتقاس‬ ‫الزمن‬ ‫وحدة‬ ‫في‬ ‫النووية‬ ‫االضمحالالت‬ ‫عدد‬ ‫وهي‬
• Number of nuclear decays per unit time
• Its SI unit, becquerel (Bq), corresponds to one decay per second.

1.1 INTRODUCTION

Thanks

Chapter 1. TABLE OF CONTENTS
1.1. Introduction ‫مقدمة‬
1.2. Classification of radiation ‫اإلشعاع‬ ‫تصنيف‬
1.3. Atomic and nuclear structure ‫للمادة‬ ‫والنووي‬ ‫الذري‬ ‫التركيب‬
1.4. X rays ‫السينية‬ ‫األشعة‬

• The SI International system of units is founded on base units for seven
physical quantities:
• Quantity SI unit
• length meter (m)
• mass m kilogram (kg)
• time t second (s)
• electric current (I) ampere (A)
• temperature (T) Kelvin (K)
• amount of substance mole (mol)
• luminous intensity candela (cd)

• The constituent particles forming an atom are
protons, neutrons and electrons. Protons and neutrons
are known as nucleons and form the nucleus of the atom.

• Protons: are particles with a positive charge
• Neutron: Within the nucleus without charge
• Electrons: are negatively charged particles and
mass equal to 1/1840 of atomic mass unit.
•
Atomic mass unit: It is defined as one twelfth
of the mass of an atom of carbon-12 .

Geiger and Marsden found that:
•
positive charge
negative electrons
Thomson atomic model Rutherford atomic model
positive charge
negative electrons
Visible lines of emission spectrum for Hydrogen

• Known as the atomic number of any atom (element – isotope)?
• 1-The number of photons in the atom
• 2-The number of neutrons in the atom
• 3-The number of protons in the atom
• 4-Total number of protons and neutrons In the nucleus
• Atom
• 1-Positively charged particles in the nucleus of the atom.
• 2- Particles circulate around the nucleus in the atom.
• 3-The basic construction unit in the article.
• 4- particles with no electrical charge and in the nucleus of the atom.
• 5- Atomic substances have the same number of protons

•Protons
•neutrons

• Atomic number
• 1 - atoms of a certain element have the same number of protons but different numbers of
neutrons.
• 2-The total number of protons and neutrons inside the nucleus of the atom.
• 3 - A general expression that symbolizes any counterparty to any element.
• 4-The number of protons in an atom.
• Known mass number of the atom?
• 1-The number of photons in the atom
• 2-The number of neutrons in the atom
• 3-The number of protons in the atom
• 4-Total number of protons and neutrons In the nucleus

• electron
• 4- particles with no electrical charge and in the nucleus of
the atom.
• element
• 4- particles with no electrical charge and in the nucleus of
the atom.

• According to the Bohr model of the atom nucleus of an
atom, which consists?
• 1-The nucleus is made up of protons and neutrons and
orbits around electrons in orbits.
• 2- Nucleus by protons, neutrons and electrons.
• 3-The nucleus is made up of protons and electrons and is
orbited by neutrons
• According to the Bohr model of atoms, electrons can
move freely within the atom( ).
• According to the Bohr model of the atom when the
electrons are able to change its orbit?

Isotopes, radioisotopes and radionuclide's
•Isotopes are atoms of an element
•1- It has the same number of protons
•2- It has a different number of neutrons.
•3 - have the same chemical properties .. Why?
•4 - The atomic mass has different ........ Why?
•5. They may have different radiological properties.

4 RADIOACTIVITY
•DR. MOHAMED ADNAN
•HTTPS://TWITTER.COM/GHINSTITUTESA
HTTP://ROADINSTITUTE.EDU.SA/PAGES/DEFAULT.ASPX

1.2 ATOMIC AND NUCLEAR STRUCTURE
1.2.7 RADIOACTIVITY
• Radioactivity is a process by which an unstable nucleus (parent)
decays into a new nuclear configuration (daughter) that may be
stable or unstable.
• Radioactive decay involves a transition from the quantum state
of the parent P to a quantum state of the daughter D.
• The energy difference between the two quantum states is called
the decay energy Q

1.2.7 RADIOACTIVITY
• All radioactive processes are governed by the same formalism
based on:
• Specific activity a is the parent’s activity per unit mass:
NA Avogadro’s number
A atomic mass number
A(t) = N(t)
a =
A (t)
M
=
N(t)
M
=
NA
A

1.2.7 RADIOACTIVITY
• Activity represents the total number of disintegrations (decays) of
parent nuclei per unit time.
• The SI unit of activity is the becquerel (1 Bq = 1 s-1).
Both becquerel and hertz correspond to s-1 yet hertz expresses
frequency of periodic motion, while becquerel expresses activity.
• The older unit of activity is the curie , originally
defined as the activity of 1 g of radium-226.
Currently, the activity of 1 g of radium-226 is 0.988 Ci.
REVIEW OF RADIATION ONCOLOGY PHYSICS: A HANDBOOK FOR TEACHERS AND STUDENTS - 1.2.7 SLIDE 5
(1 Ci = 3.7 1010
s−1
)

1.2.7 RADIOACTIVITY
• Decay of radioactive parent P into stable daughter D:
• The number of radioactive parent nuclei as a function of time t is:
• The activity of the radioactive parent as a function of time t is:
where is the initial activity at time t = 0.
NP
(t) = NP
(0)e
−Pt
AP
(t) = P
NP
(t) = P
NP
(0)e
−Pt
= AP
(0)e
−Pt
NP
(t)
AP
(t)
0
P( )
A
P
P
⎯ →
⎯ D

1.2.7 RADIOACTIVITY
Parent activity
plotted against time t
illustrating:
• Exponential decay
of the activity
• Concept of half
life
• Concept of mean
life
AP
(t)

1.2.7 RADIOACTIVITY
• Half life of radioactive parent P is the time during which
the number of radioactive parent nuclei decays from the initial
value at time t = 0 to half the initial value:
• The decay constant and the half life are related as
follows:
(t1/2
)P
NP
(0)
NP
(t = t1/2
) = (1/ 2)NP
(0) = NP
(0)e
−P (t1/2 )P
P
(t1/2
)P
P
=
ln2
(t1/2
)P

1.2.7 RADIOACTIVITY
Parent and daughter activities against time for
P
P
⎯ →
⎯ D
D
⎯ →
⎯ G
At
the parent and daughter
activities are equal and
the daughter activity reaches
its maximum.
and
t = tmax
0
max
D
d
d t t
t =
=
A
tmax
=
ln
D
P
D
− P

1.2.8 ACTIVATION OF NUCLIDES
• Radioactivation of nuclides occurs when a parent nuclide P is
bombarded with thermal neutrons in a nuclear reactor and transforms
into a radioactive daughter nuclide D that decays into a
granddaughter nuclide G.
• The probability for radioactivation to occur is governed by the cross
section for the nuclear reaction and the neutron fluence rate .
• The unit of is barn per atom where
• The unit of is
D
P D G


→ →


1 barn = 1 b = 10−24
cm2
.

 cm−2
s−1
.

1.2.8 ACTIVATION OF NUCLIDES
• An important example of nuclear activation is the production of
the cobalt-60 radionuclide through bombarding stable cobalt-
59 with thermal neutrons
• For cobalt-59 the cross section
• Typical reactor fluence rates are of the order of 1014 .
59 60
27 27
Co + n Co + 
→ 59 60
27 27
Co(n, ) Co

or
 is 37 b/atom
cm−2
s−1


1.2.9 MODES OF RADIOACTIVE DECAY
• Radioactive decay is a process by which unstable nuclei reach a more
stable configuration.
• There are four main modes of radioactive decay:
• Alpha decay
• Beta decay
• Beta plus decay
• Beta minus decay
• Electron capture
• Gamma decay
• Pure gamma decay
• Internal conversion
• Spontaneous fission

• Nuclear transformations are usually accompanied by emission of
energetic particles (charged particles, neutral particles, photons,
neutrinos)
• Radioactive decay Emitted particles
• Alpha decay particle
• Beta plus decay particle (positron), neutrino
• Beta minus decay particle (electron), antineutrino
• Electron capture neutrino
• Pure gamma decay photon
• Internal conversion orbital electron
• Spontaneous fission fission products

+
−

• In each nuclear transformation a number of physical quantities
must be conserved.
• The most important conserved physical quantities are:
• Total energy
• Momentum
• Charge
• Atomic number
• Atomic mass number (number of nucleons)

• Total energy of particles released by the transformation process is
equal to the net decrease in the rest energy of the neutral atom,
from parent P to daughter D.
• The decay energy (Q value) is given as:
M(P), M(D), and m are the nuclear rest masses of the parent,
daughter and emitted particles.
 
  2
(P) (D)
Q M M m c
= − +

• Alpha decay is a nuclear transformation in which:
• An energetic alpha particle (helium-4 ion) is emitted.
• The atomic number Z of the parent decreases by 2.
• The atomic mass number A of the parent decreases by 4.
Z
A
P → Z−2
A−4
D + 2
4
He

• Henri Becquerel discovered alpha decay in 1896; George
Gamow explained its exact nature in 1928 using the quantum
mechanical effect of tunneling.
• Hans Geiger and Ernest Marsden used 5.5 MeV alpha particles
emitted by radon-222 in their experiment of alpha particle
scattering on a gold foil.
• Kinetic energy of alpha particles released by naturally
occurring radionuclides is between 4 and 9 MeV.

• Best known example of alpha decay is the transformation of
radium-226 into radon-222 with a half life of 1600 y.
88
226
Ra → 86
222
Rn+
Z
A
P → Z−2
A−4
D + 2
4
He

• Beta plus decay is a nuclear transformation in which:
• A proton-rich radioactive parent nucleus transforms a proton into a
neutron.
• A positron and neutrino, sharing the available energy, are ejected from
the parent nucleus.
• The atomic number Z of the parent decreases by one; the atomic mass
number A remains the same.
• The number of nucleons and total charge are conserved in the beta
decay process and the daughter D can be referred to as an isobar of the
parent P.
Z
A
P → Z-1
A
D + e+
+e
p → n+ e+
+e

• An example of a beta plus decay is the transformation of
nitrogen-13 into carbon-13 with a half life of 10 min.
Z
A
P → Z-1
A
D + e+
+e
p → n+ e+
+e
7
13
N→ 6
13
C + e+
+e

• Beta minus decay is a nuclear transformation in which:
• A neutron-rich radioactive parent nucleus transforms a neutron into a
proton.
• An electron and anti-neutrino, sharing the available energy, are ejected
from the parent nucleus.
• The atomic number Z of the parent increases by one; the atomic mass
• The number of nucleons and total charge are conserved in the beta
decay process and the daughter D can be referred to as an isobar of the
parent P.
n→ p + e−
+e Z
A
P → Z+1
A
D + e−
+e

• An example of beta minus decay is the transformation of
cobalt-60 into nickel-60 with a half life of 5.26 y.
n→ p + e−
+e
Z
A
P → Z+1
A
D + e−
+e
27
60
Co → 28
60
Ni+ e−
+e

• Electron capture decay is a nuclear transformation in which:
• A nucleus captures an atomic orbital electron (usually K shell).
• A proton transforms into a neutron.
• A neutrino is ejected.
• The atomic number Z of the parent decreases by one; the atomic mass
• The number of nucleons and total charge are conserved in the beta decay
process and the daughter D can be referred to as an isobar of the parent P.
p + e−
= n+e

−
+ = +
A A
Z Z-1 e
P e D

• An example of nuclear decay by electron capture is the
transformation of berillium-7 into lithium-7
p + e−
= n+e
Z
A
P + e−
= Z+1
A
D +e
4
7
Be + e−
= 3
7
Li+e

• Gamma decay is a nuclear transformation in which an excited
parent nucleus P, generally produced through alpha decay,
beta minus decay or beta plus decay, attains its ground state
through emission of one or several gamma photons.
• The atomic number Z and atomic mass number A do not change
in gamma decay.

❑ In most alpha and beta decays the daughter de-excitation
occurs instantaneously, so that we refer to the emitted gamma
rays as if they were produced by the parent nucleus.
❑ If the daughter nucleus de-excites with a time delay, the excited
state of the daughter is referred to as a metastable state and
process of de-excitation is called an isomeric transition.

• Examples of gamma decay are the transformation of cobalt-60
into nickel-60 by beta minus decay, and trans-formation of
radium-226 into radon-222 by alpha decay.

• Internal conversion is a nuclear transformation in which:
• The nuclear de-excitation energy is transferred to an orbital electron
(usually K shell) .
• The electron is emitted form the atom with a kinetic energy equal to the
de-excitation energy less the electron binding energy.
• The resulting shell vacancy is filled with a higher-level orbital electron
and the transition energy is emitted in the form of characteristic photons
or Auger electrons.
Z
A
X*
→ Z
A
X+
+ e−

• An example for both the emission of gamma photons and
emission of conversion electrons is the beta minus decay of
cesium-137 into barium-137 with a half life of 30 y.
55
137
Cs → 56
137
Ba + e−
+ e
n→ p + e−
+e
Z
A
P → Z+1
A
D + e−
+e

• Spontaneous fission is a nuclear transformation by which a high
atomic mass nucleus spontaneously splits into two nearly equal
fission fragments.
• Two to four neutrons are emitted during the spontaneous fission
process.
• Spontaneous fission follows the same process as nuclear fission
except that it is not self-sustaining, since it does not generate the
neutron fluence rate required to sustain a “chain reaction”.

• In practice, spontaneous fission is only energetically feasible for
nuclides with atomic masses above 230 u or with .
• The spontaneous fission is a competing process to alpha decay;
the higher is A above uranium-238, the more prominent is the
spontaneous fission in comparison with the alpha decay and the
shorter is the half-life for spontaneous fission.
Z2
/A  235

2 RADIATION
INTERACTIONS
WITH MATTER
•DR. MOHAMED ADNAN
•HTTPS://TWITTER.COM/GHINSTITUTESA
HTTP://ROADINSTITUTE.EDU.SA/PAGES/DEFAULT.ASPX

CHAPTER 1. TABLE OF CONTENTS
1.1. INTRODUCTION
1.3. ELECTRON INTERACTIONS
1.4. PHOTON INTERACTIONS
Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 1.

1.3 ELECTRON INTERACTIONS
• AS AN ENERGETIC ELECTRON TRAVERSES MATTER, IT UNDERGOES
COULOMB INTERACTIONS WITH ABSORBER ATOMS, I.E., WITH:
• ATOMIC ORBITAL ELECTRONS
• ATOMIC NUCLEI
• THROUGH THESE COLLISIONS THE ELECTRONS MAY:
• LOSE THEIR KINETIC ENERGY (COLLISION AND RADIATION LOSS)
• CHANGE DIRECTION OF MOTION (SCATTERING)
Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 1.3 Slide 1

1.3ELECTRON INTERACTIONS
• ENERGY LOSSES ARE DESCRIBED BY STOPPING POWER.
• SCATTERING IS DESCRIBED BY ANGULAR SCATTERING POWER.
• COLLISION BETWEEN THE INCIDENT ELECTRON AND AN ABSORBER ATOM
MAY BE:
• ELASTIC
• INELASTIC
Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 1.3 Slide2

• IN AN ELASTIC COLLISION THE INCIDENT ELECTRON IS
DEFLECTED FROM ITS ORIGINAL PATH BUT NO ENERGY LOSS
OCCURS.
• IN AN INELASTIC COLLISION WITH ORBITAL ELECTRON THE
INCIDENT ELECTRON IS DEFLECTED FROM ITS ORIGINAL PATH
AND LOSES PART OF ITS KINETIC ENERGY.
• IN AN INELASTIC COLLISION WITH NUCLEUS THE INCIDENT
ELECTRON IS DEFLECTED FROM ITS ORIGINAL PATH AND LOSES
PART OF ITS KINETIC ENERGY IN THE FORM OF
BREMSSTRAHLUNG.

THE TYPE OF INELASTIC INTERACTION THAT AN ELECTRON UNDERGOES WITH A
PARTICULAR ATOM OF RADIUS A DEPENDS ON THE IMPACT PARAMETER B OF
THE INTERACTION.

• FOR , THE INCIDENT ELECTRON WILL UNDERGO A SOFT COLLISION
WITH THE WHOLE ATOM AND ONLY A SMALL AMOUNT OF ITS KINETIC
ENERGY (FEW %) WILL BE TRANSFERRED FROM THE INCIDENT ELECTRON
TO ORBITAL ELECTRON.
b  a

• FOR , THE ELECTRON WILL UNDERGO A HARD COLLISION WITH
AN ORBITAL ELECTRON AND A SIGNIFICANT FRACTION OF ITS KINETIC
ENERGY (UP TO 50%) WILL BE TRANSFERRED TO THE ORBITAL
ELECTRON.
b  a

• FOR , THE INCIDENT ELECTRON WILL UNDERGO A RADIATION
COLLISION WITH THE ATOMIC NUCLEUS AND EMIT A
BREMSSTRAHLUNG PHOTON WITH ENERGY BETWEEN 0 AND THE
INCIDENT ELECTRON KINETIC ENERGY.
b  a

1.3.1 ELECTRON-ORBITAL ELECTRON INTERACTIONS
• INELASTIC COLLISIONS BETWEEN THE INCIDENT ELECTRON AND AN
ORBITAL ELECTRON ARE COULOMB INTERACTIONS THAT RESULT IN:
• ATOMIC IONIZATION:
EJECTION OF THE ORBITAL ELECTRON FROM THE ABSORBER ATOM.
• ATOMIC EXCITATION:
TRANSFER OF AN ATOMIC ORBITAL ELECTRON FROM ONE ALLOWED
ORBIT (SHELL) TO A HIGHER LEVEL ALLOWED ORBIT.
• ATOMIC IONIZATIONS AND EXCITATIONS RESULT IN COLLISION ENERGY
LOSSES EXPERIENCED BY THE INCIDENT ELECTRON AND ARE
CHARACTERIZED BY COLLISION (IONIZATION) STOPPING POWER.
Review of Radiation Oncology Physics: A Handbook for Teachers and Students - 1.3.1 Slide 1

1.3.2 ELECTRON-NUCLEUS INTERACTION
• COULOMB INTERACTION BETWEEN THE INCIDENT ELECTRON AND AN
ABSORBER NUCLEUS RESULTS IN:
• ELECTRON SCATTERING AND NO ENERGY LOSS (ELASTIC COLLISION):
CHARACTERIZED BY ANGULAR SCATTERING POWER
• ELECTRON SCATTERING AND SOME LOSS OF KINETIC ENERGY IN THE FORM
OF BREMSSTRAHLUNG (RADIATION LOSS):
CHARACTERIZED BY RADIATION STOPPING POWER

1.3.2 ELECTRON-NUCLEUS INTERACTION
• BREMSSTRAHLUNG PRODUCTION IS GOVERNED BY THE LARMOR
RELATIONSHIP:
.
P =
q2
a2
6o
c3

1.3.2 ELECTRON-NUCLEUS INTERACTIONS
• THE ANGULAR DISTRIBUTION OF THE EMITTED BREMSSTRAHLUNG
PHOTONS IS IN GENERAL PROPORTIONAL TO:
sin2

(1−  cos)5

• ELECTRONS TRAVERSING AN ABSORBER LOSE THEIR KINETIC ENERGY
THROUGH IONIZATION COLLISIONS AND RADIATION COLLISIONS.
• THE RATE OF ENERGY LOSS PER GRAM AND PER CM2 IS CALLED THE MASS
STOPPING POWER AND IT IS A SUM OF TWO COMPONENTS:
• MASS COLLISION STOPPING POWER
• MASS RADIATION STOPPING POWER
• THE RATE OF ENERGY LOSS FOR A THERAPY ELECTRON BEAM IN WATER
AND WATER-LIKE TISSUES, AVERAGED OVER THE ELECTRON’S RANGE, IS
ABOUT 2 MEV/CM.
1.3.3 Stopping power

1.3.3 STOPPING POWER
❑ The rate of energy loss for collision interactions depends on:
• Kinetic energy of the electron.
• Electron density of the absorber.

BREMSSTRAHLUNG PRODUCTION
THROUGH RADIATIVE LOSSES IS
MORE EFFICIENT FOR HIGHER
ENERGY ELECTRONS AND HIGHER
ATOMIC NUMBER ABSORBERS
❑ The rate of energy loss for radiation interactions (brems-
strahlung) is approximately proportional to:
• Kinetic energy of the electron.
• Square of the atomic number of the absorber.
Solid lines: mass radiation
stopping power
Dotted lines: mass collision
stopping power

• TOTAL MASS STOPPING POWER FOR ELECTRONS IN WATER, ALUMINUM
AND LEAD AGAINST THE ELECTRON KINETIC ENERGY (SOLID CURVES).
SOLID LINES:
TOTAL MASS STOPPING POWER
DASHED LINES:
MASS COLLISION STOPPING POWER
DOTTED LINES:
MASS RADIATION STOPPING POWER
(S/)tot

1.3.4 MASS ANGULAR SCATTERING POWER
• THE ANGULAR AND SPATIAL SPREAD OF A PENCIL ELECTRON BEAM
TRAVERSING AN ABSORBING MEDIUM CAN BE APPROXIMATED WITH A
GAUSSIAN DISTRIBUTION.

1.4 PHOTON INTERACTIONS
1.4.1 TYPES OF INDIRECTLY IONIZING PHOTON IRRADIATIONS
IONIZING PHOTON RADIATION IS CLASSIFIED INTO FOUR CATEGORIES:
• CHARACTERISTIC X RAY
RESULTS FROM ELECTRONIC TRANSITIONS BETWEEN ATOMIC SHELLS
• BREMSSTRAHLUNG
RESULTS MAINLY FROM ELECTRON-NUCLEUS COULOMB INTERACTIONS
• GAMMA RAY
RESULTS FROM NUCLEAR TRANSITIONS
• ANNIHILATION QUANTUM (ANNIHILATION RADIATION)
RESULTS FROM POSITRON-ELECTRON ANNIHILATION

• IN PENETRATING AN ABSORBING MEDIUM, PHOTONS MAY EXPERIENCE
VARIOUS INTERACTIONS WITH THE ATOMS OF THE MEDIUM, INVOLVING:
• ABSORBING ATOM AS A WHOLE
• NUCLEI OF THE ABSORBING MEDIUM
• ORBITAL ELECTRONS OF THE ABSORBING MEDIUM.

• INTERACTIONS OF PHOTONS WITH NUCLEI MAY BE:
• DIRECT PHOTON-NUCLEUS INTERACTIONS (PHOTODISINTEGRATION)
OR
• INTERACTIONS BETWEEN THE PHOTON AND THE ELECTROSTATIC FIELD OF THE
NUCLEUS (PAIR PRODUCTION).
• PHOTON-ORBITAL ELECTRON INTERACTIONS ARE CHARACTERIZED AS
INTERACTIONS BETWEEN THE PHOTON AND EITHER
• A LOOSELY BOUND ELECTRON (COMPTON EFFECT, TRIPLET
PRODUCTION)
OR
• A TIGHTLY BOUND ELECTRON (PHOTOELECTRIC EFFECT).

• AS FAR AS THE PHOTON FATE AFTER THE INTERACTION WITH AN ATOM IS
CONCERNED THERE ARE TWO POSSIBLE OUTCOMES:
• PHOTON DISAPPEARS (I.E., IS ABSORBED COMPLETELY) AND A PORTION OF ITS
ENERGY IS TRANSFERRED TO LIGHT CHARGED PARTICLES (ELECTRONS AND
POSITRONS IN THE ABSORBING MEDIUM).
• PHOTON IS SCATTERED AND TWO OUTCOMES ARE POSSIBLE:
• THE RESULTING PHOTON HAS THE SAME ENERGY AS THE INCIDENT PHOTON AND
NO LIGHT CHARGED PARTICLES ARE RELEASED IN THE INTERACTION.
• THE RESULTING SCATTERED PHOTON HAS A LOWER ENERGY THAN THE INCIDENT
PHOTON AND THE ENERGY EXCESS IS TRANSFERRED TO A LIGHT CHARGED PARTICLE
(ELECTRON).

• THE LIGHT CHARGED PARTICLES PRODUCED IN THE ABSORBING MEDIUM
THROUGH PHOTON INTERACTIONS WILL:
• EITHER DEPOSIT THEIR ENERGY TO THE MEDIUM THROUGH COULOMB
INTERACTIONS WITH ORBITAL ELECTRONS OF THE ABSORBING MEDIUM
(COLLISION LOSS ALSO REFERRED TO AS IONIZATION LOSS).
• OR RADIATE THEIR KINETIC ENERGY AWAY THROUGH COULOMB INTERACTIONS
WITH THE NUCLEI OF THE ABSORBING MEDIUM (RADIATION LOSS).

Introduction to Radiation Physics Fundamentals

Introduction to Radiation Physics Fundamentals

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