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

• 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, ShieldingEarly radiation exposure effects: blood changes,

lowered sperm countLatent 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 RADREM/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

• 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)