Physics Of Nuclear Medicine Flashcards
WHAT IS AN ATOM?
Tiny basic building block of matter.
• The word ATOM comes from them reek word meaning
“indivisible”
ATOMIC STRUCTURE?
Electrons,
Protons, and Neutrons
What is an Electron?
It carrys a negative electric charge,
that forms a cloud around the nucleus
of an atom.
Each electron carries a
single fundamental unit of negative
electric charge, or -1.
The lightest
particles with a known mass.
• It has a mass of 9.109 x 10 -31 kg.
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Proton
It carry a positive charge of +1,
exactly the opposite electric charge
as electrons.
The number of protons
in the nucleus determines the total
quantity of positive charge in the
atom.
• The proton is very small but is fairly
massive compared to the other
particles that make up matter.
Abproton’s mass is about 1,840 times
the mass of an electron.
• Has a mass of 1.673 x 10 -27 kg.
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WHAT IS A NUETRON?
Neutral
About the same size as
protons but their mass is slightly
greater.
Without neutrons present,
the repulsion among the positively
charged protons would cause they
nucleus to fly apart.
• A particle with no charge and has a
mass of 1.675 x 10 -27 kg
Properties of Atoms
Atomic Number (Z) – the no. of protons
in the nucleus (subscript)
Atomic Mass Number (A) – the no. of
protons and no. of neutrons in the nucleus
of an atom (superscript)
Neutron Number (N) – refers to the no. of
neutro
WHAT ARE ISOTOPES?
Atoms that have the same atomic
number (Z) but different atomic
mass number (A)
ISOBARS
Atomic nuclei that have the same
atomic mass number (A) but
different in atomic number (Z).
ISOTONES
Atoms that have the same number
of neutrons but different number of
protons
ISOMER
Have the same atomic number
(Z) and same atomic mass
number (A)
GREEK ATOM
All matter was composed of
four (4) substances: Earth,
Water, Air, and Fire.
• Each substance has four (4)
basic essences: Wet, Dry,
Cold, and Hot.
JOHN DALTON
ATOM
1808
An element was composed
of identical atoms that
reacted the same way.
The physical combination of
one type of atom with
another was visualized as
being an “Eye and Hook”
Periodic Table - a table of the
chemical elements arranged in
order of atomic number
A Russian scholar who shows that if
the elements were arranged in
order of increasing atomic mass,
repetition of similar chemical
properties occurred
1869, Dimitri Mendelev
THOMSON ATOM
1890s
Electrons (cathode rays) were an
integral part of atoms
Described atom looking like a “Plum
Pudding”.
PLUM (negative electric
charges/electrons)
PUDDING (shapeless mass with
positive electrification)
RUTHERFORD
MODEL
1911
Disproved Thomson’s model of atom and he introduced the nuclear model which described the atomas containing a small, dense, positively charged center surrounded bya negative cloud electrons and he called the NUCLEAR MODEL
BOHR ATOM
1913
Improved the rutherfords description of the atom
postulated two things:
He believes that the orbital electrons loses energy when it jumps
from outer to inner orbital
He further believes that electron will gain energy when it jumps from inner to outer shell
ELECTRON
ARRANGEMENT?
The closer an electron is to the nucleus, the more it is bound
Electron Limit per Shell = 2n 2
Particulate Radiation
Ionizing radiation in the form of particles
• It has mass and charge
• Travels at the speed of light in free space
• Most originates in the nucleus of an atom
• Consists of minute bits of matter travelling
with a certain velocity and therefore
possessing kinetic energy.
• Alpha and Beta Particle Radiation.
Alpha?
do not penetrate matter as easily as
other types of radiation
• has approximately of 4 amu, charge of +2
• best described as doubly ionized helium
• produced by radioactive decay, primarily
of heavy atoms
• low penetrating ability, no medical uses
Beta?
Negatron?
Positron?
more penetrating than alpha particles
• have a mass of 0.00055 amu
• has a charge of either -1 or +1
Negatron - negative electron; produced
by radioactive decay
Positron - positive electron; produced
by radioactive decay or pair production;
used in nuclear medicine, PET studies
Non particulate
EM RADIATION
Radiation in the form of waves
• it has NO mass and NO charge
• travels at the speed of light in free space
• it has the combined properties of
electricity and magnetism
• disturbance consisting of electric and
magnetic field components and
traveling through space with the speed
of light.
Modes of Human Exposure
Irradiation and Contamination
Two types of Irradiation
External and Internal radiation
What is contamination?
Undesired presence of radioactive materials on
any substance in concentrations greater than
those which occur naturally so much so as to cause
a technical inconvenience or a radiation hazard
cause by spillage or breakage
4 CLASSIFICATION OF HUMAN
EXPOSURE
- BACKGROUND RADIATION EXPOSURE
- MEDICAL EXPOSURE
- OCCUPATIONAL EXPOSURE
- EXPOSURE OF THE MEMBERS OF GENERAL
PUBLIC
