This document provides information about a medical physics course taught by Dr. Munir Ahmad. It includes: - The examination structure which involves attendance, quizzes, assignments, a midterm, and final exam. - The main topics to be covered including radiation physics, biology, medical imaging, radiotherapy, and protection. - An outline of some of the lecture topics, including atoms and isotopes, nuclear states, radiation types, and cell biology.

1. Advance Medical Physics
DR. MUNIR AHMAD
POSTDOC MEDICAL IMAGING
PHD MEDICAL PHYSICS, UCL, UK

2. Examination Structure
 Attendance (20 points)
 Class quiz (5 points)
 Assignments (5 points)
 Midterm (30 points)
 Final (40 points)
 FINAL & MIDTERM examination paper structure
 50 points both, having 20 points mcqs, 20 points for numerical and 10 points for definitions

3. Main Topics Covered
 Introduction to Radiation Physics (3 lectures with assignments)
 Introduction to Radiation Biology (3 lecture with assignments)
 Midterm
 Medical Imaging (4 lectures with assignments)
 Radiation Therapy (3 lectures assignments)
 Radiation Protection (3 lectures assignments)
 Final

4. Radiation Physics
 Atoms and Isotopes
 Nuclear States and Disintegration
 Radioactivity and Radioactive Series
 Radiation Types and Properties
 Radiation Detection
 Radiation Interactions with Matter

5. Radiation Biology
 Introduction to cell biology
 Effects of Radiation on cells
 Radiation Exposure
 Radiation Dose
 Absorbed Dose
 Effective Dose
 Dose measurements

6. Medical Applications
 Diagnostic
 Therapeutic

7. Medical Imaging
 Basics of Medical imaging (Anatomical and Physiological)
 Medical Imaging Types and Techniques
 XR imaging
 Ultrasound Imaging
 PET/SPECT
 MRI
 EIT

8. Radiotherapy
 Radiotherapy Machines
 LINAC
 Treatment Planning
 Protocols

9. Lecture 1
 Atoms and Isotopes
 Nuclear States and Disintegration

10. Atomic Theory
 Three fundamental parts of an atom are:
 protons
 electrons
 neutrons
 Structure of the atom is:
 protons and neutrons are found in the nucleus
 electrons are located outside of the nucleus

11. Atomic Theory
 Atoms are building blocks of elements
 Similar atoms in each element
 Different from atoms of other elements
 Two or more different atoms bond in simple ratios to
form compounds

12. Basic Properties of Subatomic Particles
Particle Mass, g
Relative
mass to
C-12, amu
Charge,
Coulombs
Unit
Charge
proton 1.6726 x 10
-24
1.00728 1.67 x 10-19
+1
electron 9.1096 x 10
-28
0.000549 -1.67 x 10-19
-1
neutron 1.6749x 10
-24
1.00867 0 0

13. X
A
Z
Element
Symbol
Mass
Number
Atomic
Number
Nuclide – Representation of an atom

14. Counts the number of
protons
in an atom
 It tells the total positive charge on the atomic nucleus.
 Differentiates the element from others.
 Influences the nuclei stability.
 In neutral atom equals the number of negative charges or
electrons.
Atomic Number (Z)

15. State the number of protons for atoms of each of the following:
A. Nitrogen
1) 5 protons 2) 7 protons 3) 14 protons
B. Sulfur
1) 32 protons 2) 16 protons 3) 6 protons
C. Barium
1) 137 protons 2) 81 protons 3) 56 protons
Counting Protons

16. Counting Protons
State the number of protons for atoms of each of the following:
A. Nitrogen
1) 5 protons 2) 7 protons 3) 14 protons
B. Sulfur
1) 32 protons 2) 16 protons 3) 6 protons
C. Barium
1) 137 protons 2) 81 protons 3) 56 protons

17. Counts the number of
protons and neutrons
in an atom
Mass Number
 It tells the total number of protons and neutron in the nucleus.
 Differentiates the atom from other atoms of the same elements.
 Influences the nuclei stability.
 In neutral atom equals the number of negative charges or electrons.

18. Few More Element Nuclides

19.  Atoms with the same number of protons (Atomic
Number), but different numbers of neutrons (Mass
Number).
 Atoms of the same element (same atomic number) with
different mass numbers
Isotopes of chlorine
35 37
Cl Cl
17 17
chlorine - 35 chlorine - 37
Isotopes

20. Naturally occurring carbon consists of three isotopes, 12C,
13C, and 14C. State the number of protons, neutrons, and
electrons in each of these carbon atoms.
12C 13C 14C
6 6 6
#P ___6____ ___6____
___6____
#N ___6____ ___7____
___8____
Counting Protons and Neutrons

21. An atom of zinc has a mass number of 65.
A. Number of protons in the zinc atom?
1) 30 2) 35 3) 65
B. Number of neutrons in the zinc atom?
1) 30 2) 35 3) 65
C. What is the mass number of a zinc isotope
with 37 neutrons?
1) 37 2) 65 3) 67
Protons, Neutrons and Electrons

22. Write the atomic symbols for atoms with the following:
A. 8 p+, 8 n, 8 e- ___________
B. 17p+, 20n, 17e- ___________
C. 47p+, 60 n, 47 e- ___________
Assignment - I

23.  A scale designed for atoms gives their small atomic masses in atomic
mass units (amu)
 An atom of 12C was assigned an exact mass of 12.00 amu
 Relative masses of all other atoms was determined by comparing each
to the mass of 12C
 An atom twice as heavy has a mass of 24.00 amu. An atom half as
heavy is 6.00 amu.
 Gives the mass of “average” atom of each element compared to 12C
 Average atom based on all the isotopes and their abundance %
 Atomic mass is not a whole number
Relative Atomic Mass

24. Calculating Atomic Mass
 Percent(%) abundance of isotopes
 Mass of each isotope of that element
 Weighted average =
mass isotope1(%) + mass isotope2(%) + …
100 100

25. Isotopes Mass of Isotope Abundance
24Mg = 24.0 amu 78.70%
25Mg = 25.0 amu 10.13%
26Mg = 26.0 amu 11.17%
Atomic mass (average mass) Mg = 24.3 amu
Mg
24.3
Example – Atomic Mass of Mg

26. 1. Gallium is a metallic element found in small lasers
used in compact disc players. In a sample of gallium,
there is 60.2% of gallium-69 (68.9 amu) atoms and 39.8%
of gallium-71 (70.9 amu) atoms. What is the atomic mass
of gallium?
Assignment - II
2. A sample of boron consists of 10B (mass 10.0 amu) and 11B
(mass 11.0 amu). If the average atomic mass of B is 10.8 amu,
what is the % abundance of each boron isotope?

27. 27
Discovery of the Neutron
 Rutherford proposed the atomic structure with the massive nucleus in 1911.
 Scientists knew which particles compose the nucleus in 1932.
 Reasons why electrons cannot exist within the nucleus:
1) Nuclear size
The uncertainty principle puts a lower limit on its kinetic energy that is much larger that
any kinetic energy observed for an electron emitted from nuclei.
2) Nuclear spin
If a deuteron consists of protons and electrons, the deuteron must contain 2 protons and 1
electron. A nucleus composed of 3 fermions must result in a half-integral spin. But it has
been measured to be 1.

28. 28
Discovery of the Neutron
3) Nuclear magnetic moment:
The magnetic moment of an electron is over 1000 times larger than that of a proton.
The measured nuclear magnetic moments are on the same order of magnitude as the
proton’s, so an electron is not a part of the nucleus.
 In 1930 the German physicists
Bothe and Becker used a
radioactive polonium source
that emitted α particles. When
these α particles bombarded on
beryllium, the radiation
penetrated several centimeters
of lead.

29. 29
Discovery of the Neutron
 The electromagnetic radiation (photons) are called gamma rays which have energies
on the order of MeV.
 Curie and Joliot performed several measurements to study penetrating high-energy
gamma rays.
 In 1932 Chadwick proposed that the new radiation produced by α + Be consisted of
neutrons. His experimental data estimated the neutron’s mass as somewhere between
1.005 u and 1.008 u, not far from the modern value of 1.0087 u.

30. 30
Sizes and Shapes of Nuclei
 Rutherford concluded that the range of the nuclear force must be less than about 10−14
m.
 Assume that nuclei are spheres of radius R.
 Particles (electrons, protons, neutrons, and alphas) scatter when projected close to the
nucleus.
 It is not obvious whether the maximum interaction distance refers to the nuclear size
(matter radius), or whether the nuclear force extends beyond the nuclear matter (force
radius).
 The nuclear force is often called the strong force.
Nuclear force radius ≈ mass radius ≈ charge radius

31. 31
Sizes and Shapes of Nuclei
 The nuclear radius may be approximated to be R = r0A1/3
where r0 ≈ 1.2 × 10−15 m.
 We use the femtometer with 1 fm = 10−15 m, or the fermi.
 The lightest nuclei by the Fermi distribution for the nuclear charge density ρ(r) is

32. 32
Sizes and Shapes of Nuclei
 If we approximate the nuclear
shape as a sphere,
 The nuclear mass density is
2.3 × 1017 kg / m3.
The shape of the Fermi distribution

33. 33
The Deuteron
 The determination of how the neutron and proton are bound together in a deuteron.
 The deuteron mass = 2.013553 u.
 The mass of a deuteron atom = 2.014102 u.
 The difference = 0.000549 u. the mass of an electron.
 The deuteron nucleus is bound by a mass-energy Bd.
 The mass of a deuteron is
 Add an electron mass to each side,

34. 34
Nuclear Forces
 The internucleon potential has a “hard core” that prevents the nucleons from approaching
each other closer than about 0.4 fm.
 The proton has charge radius up to 1 fm.
 Two nucleons within about 2 fm of each other feel an attractive force.
 The nuclear force (short range):
 It falls to zero so abruptly with interparticle separation. stable.
 The interior nucleons are completely surrounded by other nucleons with which they interact.
 The only difference between the np and pp potentials is the Coulomb potential shown for r ≥ 3
fm for the pp force.

35. 35
Nuclear Forces
 The nuclear force is known to be spin dependent.
 The neutron and proton spins are aligned for the bound state of the deuteron, but there is
no bound state with the spins antialigned.
 The nn system is more difficult to study because free neutrons are not stable from
analyses of experiments.
 The nuclear potential between two nucleons seems independent of their charge (charge
independence of nuclear forces).
 The term nucleon refers to either neutrons or protons because the neutron and proton
can be considered different charge states of the same particle.

36. 36
Nuclear Stability
 The binding energy of a nucleus against
dissociation into any other possible combination of
nucleons. Ex. nuclei R and S.
 Proton (or neutron) separation energy:
 The energy required to remove one proton (or neutron)
from a nuclide.
 All stable and unstable nuclei that are long-lived
enough to be observed.

37. 37
Nuclear Stability
 The line representing the stable nuclides is the line of stability.
 It appears that for A ≤ 40, nature prefers the number of protons and neutrons in the nucleus to be about
the same Z ≈ N.
However, for A ≥ 40, there is a decided preference for N > Z because the nuclear force is independent
of whether the particles are nn, np, or pp.
 As the number of protons increases, the Coulomb force between all the protons becomes stronger
until it eventually affects the binding significantly.
 The work required to bring the charge inside the sphere from infinity is

38. 38
Nuclear Stability
 For a single proton,
 The total Coulomb repulsion energy in a nucleus is
 For heavy nuclei, the nucleus will have a preference for fewer protons than neutrons because of the large
Coulomb repulsion energy.
 Most stable nuclides have both even Z and even N (even-even nuclides).
 Only four stable nuclides have odd Z and odd N (odd-odd nuclides).

39. 39
The Liquid Drop Model
 Treats the nucleus as a collection of interacting particles in a liquid drop.
 The total binding energy, the semi-empirical mass formula is
 The volume term (av) indicates that the binding energy is approximately the sum of all the interactions
between the nucleons.
 The second term is called the surface effect because the nucleons on the nuclear surface are not
completely surrounded by other nucleons.
 The third term is the Coulomb energy.

40. 40
The Liquid Drop Model
 The fourth term is due to the symmetry energy. In the absence of Coulomb forces, the nucleus
prefers to have N ≈ Z and has a quantum-mechanical origin, depending on the exclusion principle.
 The last term is due to the pairing energy and reflects the fact that the nucleus is more stable for even-
even nuclides. Use values given by Fermi to determine this term.
where Δ = 33 MeV·A−3/4.
 No nuclide heavier than has been found in nature. If they ever existed, they must have decayed
so quickly that quantities sufficient to measure no longer exist.

41. 41
Binding Energy Per Nucleon
 Use this to compare the relative
stability of different nuclides.
 It peaks near A = 56.
 The curve increases rapidly,
demonstrating the saturation
effect of nuclear force.
 Sharp peaks for the even-even
nuclides 4He, 12C, and 16O
tight bound.

42. 42
Nuclear Models
 The difference of the shape between the
proton and the neutron are due to the
Coulomb interaction on the proton.
 Nuclei have a Fermi energy level which is
the highest energy level filled in the
nucleus.
 In the ground state of a nucleus, all the
energy levels below the Fermi level are
filled.
The nuclear potential felt by the neutron and the proton

43. 43
Nuclear Models
 Energy-level diagrams for 12C and 16O.
 Both are stable because they are even-even.
Case 1: If we add one proton to 12C
to make
unstable
Case 2: If we add one neutron to 12C
to make 13C:
stable