RAD 350 Chapter 1
I.
Matter – anything that occupies space;
a. consists of atoms and molecules
b. Primary characteristic is MASS – the quantity of matter contained in a physical
object
i. weight describes mass in an area with a gravitational “pull (mass on earth
and the moon is the SAME, but the gravitational pull is different
ii. MASS also remains the SAME regardless of physical form (solid, liquid,
gas) and has the SAME number of particles in ANY form.
II.
There are 7 forms of energy:
a. Potential – capacity to do work by virtue of position
b. Kinetic – energy of motion
c. Chemical – energy released via chemical reaction
d. Electrical – electrons moving
e. Thermal – heat (motion at the molecular level)
f. Nuclear – energy in/from the nucleus of an atom
g. Electromagnetic – x-ray and magnetic energy (uv rays, radio waves, microwaves,
infrared and visible light)
III.
MASS – ENERGY: Einstein’s theory of relativity E=MC2
a. E= Energy, M=mass, C= Speed of light (3 X 1010 cm/sec; 3 X 108 m/sec)
IV
Radiation = Energy emitted and transferred through space.
a. Electromagnetic radiation (sunlight, microwaves, etc.) has properties of BOTH
electricity and magnetic; solar radiation, etc., CAN be REFLECTED!!! IONIZING radiation
is capable of removing an electron from an atom = “pissed off atom” minus one electron
= POSITIVE ATOM and the ejected electron = ION PAIR
b. DRAW AND LABEL/DESCRIBE AN ATOM!
Sources of ionizing radiation:
Natural sources:
Cosmic rays = emitted by the sun and stars
Terrestrial – emitted from deposits of uranium. Thorium and other
substances in the earth (radon gas is the LARGEST source – is a decayed
uranium by-product and emits ALPHA particles)
Man made – ionizing radiation : Medical/dental/TSA screening – 11% of our
annual radiation dose comes from man made sources. Other man made sources
are nuclear power, research, industrial sources and consumer items (watch dials,
exit signs, smoke detectors, etc.
V.
VI.
VII.
Wilhelm Conrad Roentgen discovered x-rays on Nov. 8, 1895 while working with a
CROOKS TUBE IN Wurzburg, Germany. MANY scientists were playing with crooks tubes
at the time. Roentgen covered the tube with paper and noticed a glass plate covered
with barium platinocyanide on a nearby table would glow whenever the tube was
energized.
a. Interesting facts about the discovery:
i. Were discovered by ACCIDENT – NOT invented!
ii. Within one month of the discovery, Roetgen had discovered ALL of the x-ray
properties we know today!
1. Injuries to humans began immediately: erythema (skin reddening),
alopecia (loss of hair), anemia (low blood counts)
Modern Radiography – radiography and fluoroscopy (moving images like a GI study)
DISCUSS A TYPICAL FLUORO UNIT!!!
a. Uses thousands of volts of electricity – KILOVOLTS (ONE Kv = 1,000 V of electric
POTENTIAL measured in EMF) KILO = 1,000
b. Uses current in MILLIAMPS – 1/1000 OF AN amp; MILLI = 1/1,000
c. Intensifying screens – converts x-rays to visible light which exposed the film
i. initially, glass plates covered with a silver halide emulsion were what x-ray
images were recorded on – “flat plate of the abdomen” is still used verbally.
Glass plates were replaced by using a flexible base (cellulose nitrate), covered
with silver halide/bromide crystals. BUT the cellulose nitrate was highly
flammable and was replaced by cellulose acetate in 1923. The xray film bas is now
made of POLYESTER
D. The FLUOROSCOPE WAS INVENTED BY Thomas Edison in 1898 (Edison’s assistant
died of radiation related problems in 1904 and Edison stopped all radiation experiments
e. Collimation = controlling the AREA the x-ray beam is permitted to expose the patient
f. Filtration of the x-ray beam = absorbs LOW ENERGY, non useful x-rays so they don’t
expose the patient
TWO IMPORTANT ITEMS ENABLED RADIOGRAPHY TO EVOLVE – SNOOK
TRANSFORMER and COOLIDGE TUBE
Radiation Protection – due to the care of technologists, radiologists and radiobiologists,
medical imaging is considered a safe profession.
a. Practice the “ten commandments of radiation protection” and practice them! Do NOT
become complacent!!!
VIII.
IX.
X.
b. Three “cardinal safety principles” TIME, DISTANCE AND SHIELDING are the standard
of safety from ionizing radiation
c. ALARA principle – as low as reasonable achievable for radiation dose as there is no
safe dose amount!
d. Ways to minimize the dosage YOU and radiation workers receive: time, distance and
shielding – wear a lead apron, eyeglasses and gloves during fluoro, wear a lead apron
while doing portables and extend the exposure cord/wire the full six foot length BEHIND
the portable, avoid holding patients and ALWAYS collimate.
e. For patients – always collimate (single MOST important thing a technologist can do to
minimize patient exposure), proper technical factors (highest OPTIMUM kVp and lowest
possible mAs). Also, filtration, intensifying screens, protective barriers/aprons and
limiting the number of exposures where possible (like on kids and pregnant ladies
Heat:
Conduction – touching a heated object
Convection – mechanical transfer of heat
Thermal radiation – emission of infra-red radiation (x-ray tube heat transfer)
X-ray units
Roentgen – exposure in AIR
RAD/Gray (Gy) – Radiation Absorbed Dose (in any absorber)
REM/Sievert (Si) – Roentgen Equivalent Man (radiation worker dose unit)
Becquerel (Bq) – quantity of radioactive material
“George’s Math”
Inverse Square Law
Old mAs – New mAs
Direct proportions/ratios