PHYSICS OF NUCLEAR MED Flashcards
Tiny basic building block of
matter
ATOM
The word ATOM comes from the
Greek word meaning
indivisible
carries a negative electric charge,
that forms a cloud around the nucleus
of an atom
electron
It is the lightest
particles with a known mass.
electron
mass of electron
9.109 x 10-31 kg
carry a positive charge of +1, exactly the opposite electric charge as electrons
protons
A proton’s mass is about ______ times the mass of an electron
1840
mass of a proton
1.673 x 10-27 kg
about the same size as protons but their mass is slightly greater
neutron
mass of a neutron
1.675 x 10-27 kg
atomic mass unit of electrons
0.000549
atomic mass unit of protons
1.00728
atomic mass unit of neutrons
1.00867
the no. of protons in the nucleus and their legend
atomic number (Z)
the no. of protons and no. of neutrons in the nucleus of an atom and their legend
atomic mass number (A)
refers to the no. of neutron
Neutron Number (N)
- alphabetic abbreviation of an element; chemical properties of an element are
determined by the number and arrangement of electrons in the orbits around the nucleus
CHEMICAL SYMBOL
Characteristics of a stable atom
Z = e = p
N = A - Z
A = p + n
Atoms that have the. same atomic number (Z) but different atomic mass number (A
isotopes
Atomic nuclei that have the same atomic mass number (A) but different in atomic number (Z)
isobars
Atoms that have the same number of neutrons but different number of protons
isotones
Have the same atomic number (Z) and same atomic mass number (A)
isomer
In this kind of atom, it stated that All matter was composed of four substances
greek atom
According to his theory:
§ 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 Affair”
John Dalton Atom 1808
A Russian scholar who shows that if the elements were arranged in order of increasing atomic mass, repetition of similar chemical properties occurred
Dimitri Mendeleev (1869)
Described atom looking like a “Plum Pudding”
Thomson Atom (1890s) (JJ Thompson)
he disproved Thomson’s model of the atom and introduced the nuclear model which described the atom as containing a small, dense, positively charged center surrounded by a negative cloud of electrons and he called the center of the atom the NUCLEUS and this was called the Nuclear Model
Rutherford Model (1911)
was a miniature of solar system (where SUN is the NUCLEUS and ELECTRONS are the PLANETS) in which the electrons revolved about the nucleus in prescribed orbits or energy levels
Bohr Atom (1913)
What were the 2 postulations of Neils Bohr?
- 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
Strength of attachment of an electron to the nucleus: the closer an electron is to the nucleus, the more it is bound.
Electron Arrangement
energy in the form of waves or particles, especially electromagnetic radiation, which includes gamma, x-ray, ultraviolet rays, visible light, and infrared rays and the particles
Radiation
- Ionizing radiation in the form of particles
- It has mass and charge
- Travels at the speed of light in free space
Particulate radiation
2 kinds of particulate radiation
alpha and beta particle radiation
How many amu does the alpha radiation have?
4 amu charge of +2
do not penetrate matter as easily as other types of radiation
alpha radiation
have a mass of 0.00055 amu
* has a charge of either -1 or +1
beta radiation
negative electron; produced by radioactive decay
negatron
positive electron; produced by radioactive decay or pair production; used in nuclear medicine, PET studies
positron
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
non-particulate radiation
a general term and may be used to describe exposure to radiation originating from any source. It may also include all types of radiation
irradiation
2 kinds of irradiation
external and internal
is specific and indicates that the exposure is due to x-rays originating from external source
External irradiation
examples of external irradiation
(Diagnostic x-ray, Teletherapy, CT-scan, Fluoroscopy, Nuclear Power Plant)
may come from internal contamination. It may result from inhalation or ingestion of radioactive materials or in some cases from direct absorption through the skin
internal irradiation
examples of internal irradiation
(Brachytherapy,
Nuclear medicine)
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.
Contamination
what are the 4 classifications of human exposure
background radiation exposure
medical exposure
occupational exposure
exposure of the members of general public
is the main source of exposure for most people.
Background exposure
deals with intentional exposure of patient for diagnostic and therapeutic purposes by technically qualified medical and paramedical personnel.
medical exposure
is the exposure obtained by an individual (radiation worker) as a result of the nature of their work particularly in the radiation area
occupational exposure
exposure which might be received by individual members of the population, as a result of their visit to a hospital, or walk by a hospital, or live or work near one where there is a presence of any radiation sources
exposure of the members of the general public
