113 Flashcards
Building block of RT undertanding abt matter &ionizing rad
Atom
Indivisible
Atomos
Greek 500bc
Cant b broken down ny further & us seprsted from each othr by an empty space
Atom
Smallest particle tha has poperties of an element
Atom
Much smaller than atom
Subatomic particles
“Evrythin is made up of atom
Democritus
Greek
500bc
All matter are composed of 4 subs &modifid by 4 essence
Aritotle
Earth water fire air
Wet dry hot cold
Diff ypes of spheres kight make up the diff elements
Atoms as solid spheres
Composed of identical atoms & could be classifid accdg to integral values of mass
Elments
Wherein particular size & # of eyes re diff for ech elemt
Eye and hook affair
Elements- identical atomz similar in looks, construction & rxn
But differ from atoms of other elements
Compound
Eye and hook affair
John dalton
1808
1st perodic table
Dmitri mendeleev
1869
Arranged in icrease atomic mss -soed then-known elements in 8 grps
Perioic table
Det by the placement of electrons in each atom same grpings (similar physica prop & chem rxn)
Elmntal grpins
Diff grps in periodic table
GROUP I :ALKALI METALS =soft metals w/ oxygen; violently reax h20
GROUP VII: HALOGENS= EASIly VPORZED w metal =water soluble salts
GROUP VIII: NOBLE GASES =H. resistant to rx w oher elem
Sir Willim crookes
1870
Cthode ray tube & tv
Xray developed
1896
William roentgen
Certain elem glowed when exposed to catjode rays
Rays no deflected by magnetc field from crt
Electrons
concluded that e were an integral part of an atom while investigating prop of cathode rays (electrons)
1897 JOSEPH JOHN (JJ) THOMPSON
prop of PLUM PUDDING MODEL
explain
plum = - charge
pudding = mass of + charge
neutral = e- = p+
EARLY QUANTUM THEORY DEVELOPED
1900
MAX PLANCK
EM ENERGY = EMIT AS QUANTIZED FORM
(QUANTA =) PHOTON)
NATURE OF LIGHT
1905
ALBERT EINSTEIN
- special and general theories of relativity
- hypothesizes about the particle nature of light.
= basis of nuclear energy.
Robert Millikan
(1908-1917)
measured Charge of a single electron ( elementary charge ==fundamental physical
constants.)
Structure of an atom developed: NUCLEAR MODEL
ERNEST RUTHERFORD
1911
NUCLEUS = MUO PROTONS
CLOUS OF E = AROUND NUCLEUS
OTHER TERM FOR NUCLEAR MODEL
PLANETARY MODEL
FATHER OF NUCLEAR P6
ERNEST RUTHERFORD
Bohr atomic model
Niels Bohr, a Danish scientist,
1913
electrons traveling in orbits around the nucleus
He also integrated the Planck
quantum theory,
Niels Bohr,
1913
EXPLAIN
Planck quantum theory
when electrons change orbits, they
emit a quantum of discrete energy.
OTHER TERM FOR Bohr atomic model
Miniature Solar
System.
WHAT PREVENTS E- FROM COLLAPSING
ORBITS
Math describes electron changes
Erwin Shrodinger
1926
Schrodinger equation = described how electrons move in waveform / how the
quantum state of a system changes with time.
neutron discovered
1932
James Chadwick
the neutron component of the atomic
nucleus
explaining the nuclear fission of uranium 235
= possible to produce elements heavier than uranium in the lab.
Nuclear fission developed
1938
Otto Hahn
the father of nuclear chemistry,
discovers nuclear fission W Lise Meitner.
Nuclear medicine and I-131
1951
Glenn Seaborg,
discoveries of the transuranium elements = advances in nuclear medicine == devt of I-131 for thyroid disease
Elementary particles smaller than the atom Murray Gell
1964
Mann + George Zweig
quark model = elementary particles have no
substructure == can’t be split
Modern Atomic Theory
20th Century
Schrodinger, Heisenberg, Einstein, and many other scientists
electrons do not orbit the nucleus
move at high speeds in an electron cloud around the nucleus. = not random patterns;
E- LOC DEP ON ITS ENERGY
UNCERTAINTY PRINCIPLE
IMPOSSIBLE TO PINPOINT LOC+ SPEED
== QUANTUM MECHANICAL MODEL OF AN ATOM
FUNDAMENTAL PARTICLES
ELECTRON
PROTON
NUCLEUS
Unit of measure used to identify the size of an atomic particle that is so small.
Atomic mass units (amu)
1 AMU =
one-twelfth of the mass of a carbon-12 atom.
A system of whole number that is used when precision is not necessary.
Atomic mass numbers
FORMULA Atomic mass numbers
“A,= “protons+neturons.”
particles contained in the nucleus of an atom,
Nucleons (protons and neutrons.)
T/F
“The atom is essentially empty space.”
T
ELECTRON
CHARGE
MASS
ATOMIC MASS #
AMU
LOC
- 9.109 X 10-31 KG
0
0.000549
SHELL
PROTON
CHARGE
MASS
ATOMIC MASS #
AMU
LOC
+
1
1.673 X10-27 KG
1
1.00728
NEUTRON
CHARGE
MASS
ATOMIC MASS #
AMU
LOC
0
1.675 X 10-27
1
1.00678 AMU
circles where the
electrons orbit is
energy levels or shells.
WHICH ORBIT HAS THE HIGHEST ENERGY LEVEL
E- in the outermost circles have higher
energy
= more effort to pull the E a greater
distance from the nucleus.
The value of n
principal
quantum number
REMOVAL / ADDITION OF E-
IONIZATION
RELN OF ENERGY LEVEL AND # OF E-
DIRECT
final location where electrons
reside.
Orbitals
ENERGY NEEDED FOR IONIZATION
34 eV
-det the chemical element and the behavior of
an atom
of protons
center-seeking force.
Centripetal force
The force that
keeps an electron in orbit.
Centripetal force
flying-out-from-the-center force.
Centrifugal Force
The force that causes an electron to travel
straight and leave the atom.
Centrifugal Force
The strength of the attachment of an electron to the nucleus.
Electron Binding Energy
alphabetic abbreviations of an element
Chemical Symbols
det the chemical properties of an element
& Arrangement of Electrons
-Number of Protons
-Symbol: Z
Atomic number
protons + neutrons
-Symbol: A
Atomic Mass Number
-Upper Left:
atomic mass (A)
-Lower Left:
atomic number (Z)
-Upper Right:
valence state (+/-)
-Lower Right:
of atoms/molecules
T/F
“The atomic number & the precise mass of an atom are equal!”
F
NOT EQUAL
smallest unit of a
compound.
Molecules
Any quantity of one type of molecule.
Chemical Compound
chemical union between atoms
formed by sharing one or more pairs of
electrons.
Covalent Bond
> The bonding that occurs because of
an electrostatic force between ions
Ionic Bond
-The primary constituents of the x-ray tube target
Tungsten (W-74) & Molybdenum (Mo-42)
-Radiographic & fluoroscopic contrast agents
Barium (Ba-56) & Iodine (I-53)
-The important component of human tissue
Carbon (C-6)
-The amount of energy (34 keV) necessary to ionize tissue atoms
Ionization Potential
T/F
“The smallest particle of an element is an atom; the smallest particle of a compound is a
molecule!”
T
the force that holds all the objects onto the Earth.
GRAVITATIONAL FORCE
force of attraction between all masses in the Universe,
ADDING MOTION TO UNIVEFRSE
CREATNG ENERGY
GRAVITATIONAL FORCE
gravitational acceleration on Earth
9.8m/s^2
gravitational acceleration on MOON
1.6m/s^2.
PROPERTIES OF GRAV FORCE
long-range
strength of only about 10^(−38) times
APPEARS IN β-
decay of a nucleus.
Weak Nuclear Force
β-decay,
nucleus emits an e- & uncharged particle called the neutrino.
PROPERTIES OF NUCLEAR FORCE
WEAKER < NF & EMF
RANGE: 10-16 M
ALLOW FUSION OF P+N == DEUTERIUM === SUN
FX OF NUCLEAR FORCE
CONVERT P TO N = RELEASING RADN
the force that causes the interaction
between electrically charged particles.
force b/n charged particles.
can be attractive or repulsive.
Electromagnetic Force
FORCE GIVEN WHEN CHARGE @ REST
Coulomb’s law: ATTRACTION AND REPULSION
PROP / FX OF EMF
LONG RANGE
BIND ATOMS / MOL TO FORM= MATTER
GEN LIGHT
strong, attractive force between nucleons in the atomic nucleus that holds
the nucleus together.
binds protons and neutrons in a nucleus.
strongest of all fundamental force
responsible for the stability of nuclei.
Strong Nuclear Force
PROP & FX OF STRONG NF
charge-independent.
short-range force.
dependent on the spin of the nuclei.
emission of particles & energy to become stable
Radioactivity
Radioactive DecaY
nucleus spontaneously emits particles & energy &transforms itself into another atom to reach stability
nucleus contains too few or too many neutrons.
OTHER TERM FOR Radioactive Decay
Radioactive Disintegration
Radioactive atoms that have the same number of protons
Radioisotopes
Two primary sources of naturally occurring radioisotopes
Uranium (U-92) & Carbon-14
TYPES OF IONIZING RADIATION
Particulate and Electromagnetic
: Mass, Energy, Velocity, Charge & Origin
Particulate Radiation
;alpha & beta Particles
Electromagnetic Radiation
; x-rays & gamma
Alpha Particle
2 protons & 2 neutrons
o Symbol: α
o Mass: 4 amu
o Charge: +2
o Origin: nucleus of heavy radioactive nuclei
o Energy: 4-7 MeV
o Range: 1-10 cm (air); <0.1 mm (soft tissue)
o Ionization Rate: 40,000 atoms/cm
Beta Particle
Light particles
▪ Symbol: β- or β+
▪ Mass: 0 amu
▪ Charge: -1 or +1
▪ Origin: nucleus of radioactive nuclei
▪ Energy: 0-7 MeV
▪ Range: 10-100 cm (air); 1-2 cm (soft tissue)
▪ Ionization Rate: several hundred of atoms/cm
same with electrons, they only differ in origin
Negative Beta Particles
The same mass with electrons
o Positrons
o Antimatter
Positive Beta Particles
often called photons
▪ It has unlimited range in matter
EMR
Photons
No mass & no charge
o Travel at the speed of light (c)
o c: 3 x 108 m/s or 1.86 x 105 mi/s
“X-rays and gamma rays are the only forms of ionizing electromagnetic radiation of radiologic interest!”
T
X-rays
Symbol: X
o Mass: 0
o Charge: 0
Origin: electron cloud
o Energy: 0-25 MeV
o Range: 0-100 m (air); 0-30 cm (soft tissue)
o Ionization Rate: 100 ip/cm (equal to beta particles)
Gamma Rays
Symbol: γ
o Mass: 0
o Charge: 0
o Origin: nucleus/radioactive nuclei
o Energy: 0-5 MeV
o Range: 0-100 m (air); 0-30 cm (soft tissue)
o Ionization Rate: 100 ip/cm (equal to beta particles)
Number of neutrons exceeds the protons
* Have both odd Z and N
Stable Nuclides
Modes of Decay
ALPHA DECAY : nuclei too large to be stable. (-4 -2)
BETA MINUS DECAY: nuclides too large for stability (+1 -0) = positron and antineutrino
BETA PLUS DECAY: nuclides too small for stability. (-1, 0 ) = positron and neutrino
ELECTRON CAPTURE: E- +P = neutron and neutrino === EMIT NEUTRINO AND XRAY
GAMMA RAY EMISSION: EXCITED NUCLEI - DECAY - 10 KEV - 5 MEV GAMMA RAY
FX OF GRAVITATIONAL FORCE
-Adding motion to the Universe
Creating energy
FX OF WEAK NUCLEAR FORCE
Converting protons into neutrons
Releasing Radiation
FX OF ELECTROMAGNETIC FORCE
Forming atoms and molecules
Generating light
FX OF STRONG NUCLEAR FORCE
Binding protons in atomic nuclei
Breaking the bond
disintegrate into a stable isotope of different elements at a decreasing rate so that
the quantity of radioactive material never quite reaches zero.
radioisotopes
radioactive material IN BQ
1 Bq =
disintegration of 1 atom each second.
FORMULA OF DECAY CONSTANT
Formula: λ =
ln (2) / T1/2
or
0.693 / T1/2
rate of decay of
radionuclides
Decay Constant
Types of Half-life
Radioactive/Physical Half-Life :
time req for a quantity of Radioactivity to be reduced to one-half its original value
Biological Half-life (Tb):
The time required for the body to eliminate one-half of the administered dose by biological processes (perspiration, urine, feces, exhalation)
Effective Half-Life (Te):
time req for a radioactive elim in the body to be diminished by 50% as a result of the combined action of radioactive decay and biological
elimination.
are manifestations of a single underlying electromagnetic
force.
Electricity and Magnetism
X-ray Imaging System-
primary function:
convert electric energy into
electromagnetic energy
study of stationary electric
charges
Electrostatics
study of the distribution of
fixed charges
Electrostatics
TYPES OF ELECTROSTATIC CHARGE
ELECTRIC POTENTIAL (V)
is potential energy per unit charge
1 V = 1 J/C
ELECTRIC CURRENT (I)
is one Coulomb of electric charge
flowing per second
1 A = 1 C/s
Positive or negative
Electric charge
Fundamental Unit (S.I.) of Electric charge
Coulomb (C)
1 C: 6 x 1018 electron charges
Transfer or movement of an electron from one object to another object.
Electrification
HOW IS Electrification CREATED
FRICTION: rubbed against another
CONTACT: touch, electrons move from one to the other
INDUCTION: the process of electrical fields acting on another without contact
Most important method
(used in the operation of electronic devices)
INDUCTION:
If object has too few or too many electrons
Electrified Object
The object that behaves as a reservoir for stray electric charges
Electric Ground
The electrostatic force is directly proportional to the product of the electrostatic
charges & inversely proportional to the square of the distance between them
Coulomb’s Law
F =
= electrostatic force (N)
k =
constant of proportionality (9x109 coulomb-meter)
The lines of force that causes charged particles to move from one pole to another
Electric Field
POINTS OUTWARD
POINTS INWARD IN Electric Field
Positive charge:
Negative charge:
Unlike charges attract; Like charges
repel
REPULSION-ATTRACTION
do not have an electric field
Uncharged particles
Charges uniformly distributed at the surface
Distribution
Sharpest curvature of a surface
Law of Concentration
The force of attraction between unlike charges or repulsion between like
charges.
Electrostatic force
IN Electrostatic force
▪ Directly proportional to the
▪ Inversely proportional to the
product of their charges
square of the distance between them
Movement INElectrostatic Laws
Only (-) charges = move along the solid conductors
Protons = tightly bound inside the nucleus
The study of electric charges in motion
Electrodynamics
Work with electric current
Electrical Engineer
Concerned with electron flow
Physicist
Movement electrons along the wire
Electric Current
Two Types of Current
Direct Current
Alternating Current
Direct Current
E- flow only one direction
o Waveform: straight line
Alternating Current
E- flow alternately in the opposite direction
o Waveform: sinusoidal
Four States of Matter
CONDUCTOR : electrons flow easily
INSULATOR : not allow electron flow
SEMICONDUCTOR : insulator & as a conductor
SUPERCONDUCTOR : e- to flow W/O resistance
Characteristics: CONDUCTOR
Variable resistance
▪ Obeys Ohm’s law
▪ Requires voltage
▪ Exs: copper (Z=29), aluminum (Z=13) & water
Characteristics: INSULATOR
▪ Does not permit electron flow
▪ Extremely high resistance
▪ Necessary with high voltage
▪ Ex: glass, rubber & clay
Characteristics: SEMICONDUCTOR
Can be conductive
▪ Can be resistive
▪ Basis for computers
▪ Ex: silicon (Si-14) & germanium (Ge-32)
Characteristics: SUPERCONDUCTOR
No resistance to electron flow
▪ No electric potential required
▪ Must be very cold
▪ Ex: niobium (Nb-41) & titanium (Ti-22)
demonstrated semiconduction
William Shockley (1946)
The property of some matter to exhibit no resistance below a critical
temperature
Superconductivity (1911)
A pathway that permits electrons to move in a complete circle from their source
through the various components & back again
Electric Circuits
The flow of electrons through a conductor
Electric Current/Electricity
Direction: always opposite the electron flow
Electric Current/Electricity
1 A: 1 C/s
measured in ohms (Ω)
Electric Resistance
More complex → the greater the resistance → decrease the electric current
T
Ohm’s Law
V = IR
2 Basic Types of Electric Circuit
SERIES CIRCUIT :
All circuit elements are connected in a line along the same conductor
PARALLEL CIRCUIT:
Elements connected at their ends rather than lying in a line along a conductor
Magnetite
o Oxide of iron (Fe3O4)
o Lodestone or leading stone
A fundamental property of forms of matter
It has no smallest unit
Magnetism
“Any charged particle in motion creates a electric field!”
F
MAGNETIC FIELD
-A property created when electrons behave as if they rotate on its axis
Electron Spin
-It is neutralized in electron pairs
Electron Spin
-It creates a magnetic field
Electron Spin
“The lines of a magnetic field are always open loop!”
F
CLOSED LOOP
-A nuclear magnetic dipole created when a magnetic field is created by
spinning electric charge
Magnetic Moment
-The basis of MRI
Magnetic Moment
▪ Any material that produces a magnetic field
▪ Has north and south pole
MAGNETS
Magnets that have two poles
BIPOLAR/DIPOLAR
The small magnet created by the electron orbit
Magnetic Dipole
An accumulation of many atomic magnets with their dipoles aligned
Magnetic Domain
The ability of a material to attract the lines of magnetic field intensity
MAGNETIC PERMEABILITY
has a high magnetic permeability
Iron
has a low magnetic permeability
Wood
The degree to which a material can be magnetized
MAGNETIC SUSCEPTIBILITY
has a high magnetic susceptibility
Iron
has a low magnetic susceptibility
Wood
TYPES OF MAGNETS
NATURAL MAGNET: from the Earth
▪ e.g., Lodestone
ARTIFICIAL-PERMANENT MAGNET:
artificially-produced
▪ A bar or horseshoe-shaped magnet
▪ e.g., compass
ELECTROMAGNETS
▪ A coil of wire wrapped around an iron core that
intensifies the magnetic field
“All matters can be classified into how it interacts with the ____________________ !”
external magnetic field
FOUR MAGNETIC STATES OF MATTER
NONMAGNETIC – unaffected by MF
▪ Wood & glass
DIAMAGNETIC – weakly repelled from both poles of MF
▪ Copper, water & plastic
PARAMAGNETIC – Weakly attracted to both poles of MF
▪ Gadolinium (Gd-64): contrast agent in M.R.I.
FERROMAGNETIC – can be strongly magnetized
▪ AlNiCoFe (Al-12, Ni-28, Co-27) & iron (Fe-26)
An excellent temporary magnet
Soft Iron
MAGNETIC LAWS
Like = repel
Unlike = attract
Imaginary lines of MF
enter = south pole
leave = north pole
force of attraction between unlike poles or
repulsion between like poles
Magnetic Force
DP = product of the magnetic pole strengths
IP = square of the distance between them
Magnetic Field Strength
SI Unit: tesla (T)
Older unit: gauss (G)
1 T: 10,000 G
He observed that a dissected frog leg twitched when touched by two different
metals
Luigi Galvani (1700’s)
HE Contributed to the development of battery
Alessandro Volta
precursor of modern battery
Voltaic Pile:
A copper-zinc plate like a Dagwood sandwich
Voltaic Pile:
Modern Battery:
carbon rod (+) & zinc cylindrical can (-)
Any device that converts some form of energy directly into electric energy
Source of Electromotive Force
He demonstrated that electricity could be used to generate magnetic fields
HANS OERSTED (1820)
It determines the direction of the magnetic field
Right-Hand Rule
A coil of wire
Solenoid
A current-carrying coil of wire wrapped around an iron core
It intensifies the induced magnetic field
Electromagnet
ADVAN OF Electromagnet
MF can be adjusted or
turned on & off
An electric current is induced in a circuit if some
part of that circuit is in a changing magnetic
field
ELECTROMAGNETIC INDUCTION
Faraday and Oersted Experiment
He observed the current in a changing magnetic field
He described the first law of electromagnetic induction
MICHAEL FARADAY
MICHAEL FARADAY’S EXPERIMENT
Changing magnetic field induces current
o The magnetic field generates electricity
o Ammeter: measures current
HANS OERSTED EXPERIMENT
Moving or spinning charges induces a MF
Electricity generates a MF
ELECTROMAGNETIC DEVICES
ELECTRIC MOTOR :
electric current produces mechanical motion
ELECTRIC GENERATOR:
Mechanical motion produces an electric
current
TRANSFORMER
It changes the intensity of alternating voltage
& current
INDUCTION MOTOR
A type of motor used with x-rays tubes
Applicable only on AC
▪ Turns ratio greater than 1
TRANSFORMER
A type of motor used with x-rays tubes
▪ It powers the rotating anode of an x-ray tube
ROTOR
-Stationary coil windings
(electromagnet)
-Situated in the protective housing but
outside the glass envelope
STATOR
TRANSFORMER LAW
Voltage and number of turns
are directly proportional
TYPES OF TRANSFORMER
CLOSED-CORE TRANSFORMER
SHELL-TYPE TRANSFORMER
square core of ferromagnetic materials built up of laminated layers of iron
Reduced energy losses caused by eddy
current
CLOSED-CORE TRANSFORMER
Has two-closed core
▪ Confines more of the magnet field lines
▪ More efficient than closed-core
SHELL-TYPE TRANSFORMER
▪ Consists of one winding and one core
▪ Step up transformer
▪ Located in the operating console
▪ controls the kVp
AUTOTRANSFORMER
consist of both electric and magnetic field waves.
waves oscillate in perpendicular planes with respect to each other and are in phase.
Electromagnetic waves
The type of energy in x-rays, radio waves, microwaves & visible light
Electromagnetic Energy
The smallest quantity of any kind of
electromagnetic energy
o It may be pictured as quantum
Photon
o Waveform: sinusoidal fashion
o Quantum: a small bundle of energy
Photon
Frequency
No. of cycles per second
✓ Equal to the number of crests or valleys that
pass the point of an observer per unit time.
✓ Inversely proportional to the wavelength.
✓ Symbol: f
✓ S.I. Unit: hertz (Hz)
▪ 1 Hz: 1 cycle/second
Wavelength
Distance from one crest to another
✓ Distance from one valley to another
✓ Distance from one point on the sine wave to the next
corresponding point
✓ Unit: Lambda (λ)
o Inversely proportional to the frequency
c: speed of light
✓ Constant SI Unit: 3 x 10^8 m/s
✓ Constant British Unit: 186,000 mi/s
The width of a waveform
✓ It is not related to wavelength or frequency
Amplitude
He showed that visible light has both electric & magnetic properties
James Clerk Maxwell (Late 19th Century)
Three Wave Parameters
Velocity, Frequency & Wavelength
used for both sound & electromagnetic energy
Electromagnetic Wave Equation
He synthesized our understanding of electromagnetic radiation
Max Planck
1918: He received the Nobel Prize
Planck’s Quantum Theory
XRS created with the speed of light (c)
XRS exist with velocity, or they
do not exist at all
PLANCK’S CONSTANT
4.15 x 10-15 Ev-s
6.63 x 10-34 J-s
They behave more like waves
Visible Light Photons
They act more like particles
X-ray Photons
Wave Particle duality
both wave & particle concepts must be
retained, because wave-like properties are exhibited in some
experiments & particle-like properties are manifested in others
“Photons interact with matter most easily when the matter is approximately the same size
as the ______________________________!”
photon wavelength
The reduction in intensity that results from
scattering & absorption
Electromagnetic Energy Attenuation
Interaction Between Light & Absorbing Material
✓ Transparency: not at all (transmission)
o e.g., window glass
✓ Translucency: partially (attenuation)
o e.g., frosted glass
✓ Opacity: completely (absorption)
o e.g., black glass
The structures that absorb x-rays
Radiopaque
The structures that transmit x-rays
Radiolucent
A continuum of
electromagnetic energy
Electromagnetic Spectrum
Electromagnetic Spectrum
Energy: 10−12 − 1010eV
o Frequency: 102 -1024 Hz
o Wavelength: 10 7-10−16 m
Radiofrequency
Range: 0.3 kHz-300 GHz
Range in M.R.I.: 1-100 mHz
Low energy & long wavelength
Microwaves
Very-short wavelength R.F.
Higher than broadcast R.F.
Lower than infrared
It is measured in cm
interacts with hotdogs & hamburgers
Infrared
Longer λ than visible light \
Shorter λ than microwaves
It heats any substance on which it shines (radiant heat)
Visible Light
occupies the smallest segment of the electromagnetic spectrum
It is measured in nanometer
o It interacts with rods & cones of the eye
o Range: 400 nm (violet) to 700 nm (red)
Visible Light
The wave of moving molecules
o It requires matter
o It cannot exist in a vacuum
Lies between visible light &
ionizing radiation
o It interacts with molecules
Ultraviolet
produced by the decay from
high energy states of atomic nuclei.
o It comes from inside the nucleus of
a radioactive atom
o It is emitted spontaneously from
radioactive material
Gamma
are used in medical imaging, radiation therapy, airport security scanners, and material characterization.
o It is emitted from the electron cloud
o It is produced in diagnostic imaging
systems
o It interacts with electrons
Xrays
Sources of gamma
gamma decay from naturally occurring radioisotopes
secondary radiation from atmosphere interactions with cosmic ray particles;
lightning strikes
gamma-ray flashes
3 Regions Important to Radiologic Science
Visible Light Region : viewing = dx
X-Ray Region: get hq img
Radiofrequency Region: MRI
Others
▪ U.V. light, infrared light, & microwave radiation
difference between x-rays &
gamma rays
their origin!”
DIFFERENCE B/N
VISIBLE LIGHT
RF
XR
“Visible light is identified by wavelength,
R.F. is identified by frequency,
x-rays are identified by energy!”
