Transcript RAD 354 * Chapter 1

RAD 354 – Chapter 1
• This class will be a FAST review of RAD 350
and will be TECHNIQUE oriented.
• Techniques, technique charts and cooling
charts as well as effects of all items on
radiation outputs/patient-matter interactions
will be stressed.
Comments by Joe –”Hey Dr. P! Good News! I passed my boards!
On the morning of the test, I got up at 5 am and took out my
notebook where I had listed all of your and Chad’s ‘bang on the
desk/board’ items and read them ALL and no B.S. like 20-25
questions were right off of your notes as you both said! When
you see the 1st and 2nd year students be sure to tell them this is
no shi*!!!. Star and study those itmes.
Matter – anything that occupies space
-consists of atoms and molecules
-primary characteristic is mass
Class discussion – Weight and mass differences
7 Forms of Energy
• Potential – capacity to work by virtue of
position
• Kinetic – energy of motion
• Chemical – energy releases in Chem reactions
• Electrical – Electron movement
• Thermal – molecular level movement
• Nuclear – energy in the nucleus of an atom
• Electromagnetic – x-ray and magnetic energy
Ionizing Radiation
• Capable of removing an orbital electron from
an atom = an ION PAIR: ejected electron
(called a negative ion) and the “upset” atom
minus an electron (destabled atom called a
“positive ion”)
Natural Radiation
• Cosmic rays – particles emitted by the sun and
stars
• Terrestrial – emitted from deposits of
uranium, thorium and other radioactive
earthly substances (like radon gas)
• Internally deposited – mainly potassium 40
(natural metabolites)
Man Made Radiation
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Medical/dental x-rays
Nuclear power plants
Industrial plants
Screening (TSA, etc), airport surveillance
Smoke detectors
Key Dates
• November 8, 1895 – X-rays discovered by
Wilhelm C. Roentgen (was using a Crook’s
Tube)
• 1886 – Fluoroscope invented by Thomas
Edison
Radiation Protection
• ALARA – As low as reasonably achievable
– Time, Distance, Shielding
Early radiation exposure effects: blood changes,
lowered sperm count
Latent effects: genetic effects, cancer
Protection Items to Consider
• Filtration – kVp driven (2.0 mm al. added at
the 70-80 kVp range + .5 mm al equiv. inher.
• Collimation – single most important thing a
tech can do!
• Intensifying screens – receptor/film-speed
combination – as fast as possible (and still get
a good image)
• Protective barriers: shielding, gonadal
shielding and PATIENT shielding!
• Scientific notation makes it easy to write large
positive or negative numbers
• “milli” = 1/1000 (milliamp)
• Kilo = 1,000 (kilovolts – kVp)
Radiation Units
• Roentgen – couloumb/kilogram (radiation in
air) that will create 2.08 X 109 ion pairs in a
cubic centimeter of air
• RAD/Gray = radiation ABSORBED dose
– 1 X 10-2 Gy = 1 RAD
REM/sievert SV = radiation equivalent man (RAD X
man’s biologic equivalent)
1 X 10-2 SV = 1 REM
RAD units con’t
• Curie (CI)/Becquerel )Bq) = radioactive
disintegration 3.7 X 1010 Bq= 1 CI
Curves
• Characteristic curve (H & D, Solarization,
Hortchkoff) optical density (OD) verses log
relative exposure (like mAs – to the .3 log)
• X-ray emission spectrum – height of the curve
= mAs – skew to the right/left is based on kVp
Review of Units
• 3 Measurable quantities of all others
– Length, mass and time
• Secondary quantities are derived from a combination of
two or more of the three
• Radiography units are: exposure, dose, dose equivalent
and radioactivity
Standardized Units
• Unit of length = meter
• Unit of time = second
• Unit of mass - kilogram
System of Measurement
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SI (meter, kilogram, second)
MKS (meter, kilogram, second)
CGS (centimeter, gram, second)
British (foot, pound, second)
Mechanics
• Deals with objects at rest (static) & in motion
(dynamic)
– Velocity = how fast an object is moving
– Acceleration = rate of change of velocity over time
Newton’s Laws of Motion
• A body will remain at rest or continue to move
with constant velocity unless acted upon
• The force acting on an object with
acceleration is equal to the mass multiplied by
acceleration
• Action/reaction = for every action there is an
equal and opposite reaction
Weight/Momentum/Work/Power
• Weight is the force of an object caused by the
downward pull of gravity (mass X gravity)
• Momentum is the product of the mass of an
object and it’s velocity
• Work is force applied to an object over a
distance
• Power is the rate of doing work or work over a
period of time
Energy = ability to do work
• Si unit is the joule
• Mechanical energy
– Kinetic energy = energy in motion
– Potential energy = stored energy by virtue of
position
Heat = kinetic energy of the random
motion of molecules
• Can be transferred a variety of ways:
– Conduction = transferred by touching or through a
material
– Convection = mechanical transfer of “hot”
molecules in gas or liquid from one place to
another
– Thermal = red glow of hot objects (infrared
emission)
Heat measurement via thermometer
• Three scales of heat measurement exist:
Celsius (C)
Fahrenheit (F)
Kelvin (K)