# Radiology Physics Chapters 1, 2, and 3 Pt 1

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### Heat

the kinetic energy of the random motion of molecules

### Potential Energy Formula

PE=mgh
Potential energy=mass x gravity x distance above earth's surface

### Kinetic Energy depends on ....

the mass of the object and on the square of its velocity

### Two forms of mechanical energy

Kinetic Energy (KE)
Potential Energy (PE)

### Calorie

the heat necessary to raise the temperature of 1g of water through 1 degree Celcius

Conduction
Convection

### Conduction

the transfer of heat by touching or through material

### Convection

the mechanical transfer of "hot" molecules in a gas or liquid from one place to another

thermal transfer of heat by emision of infared radiation, how x-ray tube cools

C= 5/9 (F-32)

F= 9/5 (C+32)

K=C+273

### How is a thermometer calibrated?

Freezing and boiling points

### Approximate Temperature Conversion

F -> C = -30, /2
C -> F = double, +30

### ICRU

International commission on radiation units and measurement

SI units

### Gy a

(R) Roentgen
Unit of radiation exposure or intenstiy

rem

Curie

### Kinetic energy formula

KE= 1/2 x mv squared

### Law of energy conservation

energy may be transformed from one form to another but it cannot be created or destroyed

### Work

force applied times the distance over which itis applied
Joule
Product of force and distance

### Work formula

w=fd
work = force times distance

### Momentum formula

p=mv
momentum=mass x velocity

### Momentum

the pruduct of mass and velocity
increased velocity = increased momentum
the total momentum before any interactino is equal to the total momentum after the interaction

0

1/6

### Weight formula

Wt=mg
Weigh= mass x gravity

1 lb = 4.5 N

### Weight (WT)

a force on the body caused by the pull of gravity on it

### Acceleration due to gravity

objects that fall to Earth accelerate at a constant rate

### Newton's Law of Acceleration/Reaction

For every action there is an equal and opposite reaction

### Force Formula

F=ma
Force = mass x acceleration

Newton = N

### Friction

the force present that will slow down a moving object

### Kinetic Energy

energy of motion
can do work because of thier motion

blood disorders

### ALARA

as low as reasonably achievable

### Filtration

metal- aluminum, copper
inserted into x-ray housing so that low-energy x-rays are absorbed before they reach tehe patient (little diagnostic value)

### Collimation

restrics the useful x-ray beam to that part of the body to be imaged and thereby spares adjacent tissue from uneccessary radiation

lower scatter = higher contrast

### Intensifying Screens

cassette with radiographic intensifying screens on both sides
reduced exposure time with glass photographic plates

### Abdominal/Pelvic x-ray exaominations of expectant mothers should not be conducted during....

first trimester unless absolutly necessary

### H. Potter

1921
Helped with Potter-Bucky grid

### Gustav Bucky

1913
invented the stationary grid "Glitterblende"
2 months later- another patent was unknown because of the first world war (H.Potter)

### When did acceptable kVp and mAs levels become possible

matching of the coolidge tube with the snook transformer

### William D Coolidge

1913
hot-cathode x-ray tube, far superior to crookes tube
vacume tube that allowed x-ray intensity and energy to be selected seperately and with great accuracy
what x-ray tubes mainly are today

### Transformer

substitute high-voltage power supply

### H.C. Snook

1907
transformer- exceeded the capability of the Crookes tube

### Clarence Dally

Edison's Friend
Severe x-ray burn, amputation of both arms
died 1904, first x-ray fatality in the U.S.

### Fluoroscope

1898
Thomas A. Edison
barium platinocyanide found zinc cadmium sulfide and calcium tungstate

### Cellulose Nitrate

demands of army for inscreased radiologic services
substitue for glass plate

### Charles L Leonard

Found that by exposing two glass x-ray plates with the emulsion surfaces together exposure time was halved and the image was enhanced
1904 double emulsion film
1918 commercially available

### Michael Pupin

1896
demonstrated the use of intensifying screen

### William Rollins

dentist sheet of lead with hole (diaphragm) inserting a leather or aluminum filter improved diagnostic quality and reduce patient exposure, collimation and filtration

### Wilhelm Roentgen

November 8, 1895
Crookes tube
plate coated with barium platinocyanide glowed when next to the crookes tube fluorescence

### 1901

Roentgen first nobel prize in physics

### How to provide an x-ray beam that is satisfactrory for imaging

you must supply the x-ray tube with a high voltage and a sufficient electric current

### x-ray volages are measured in

kVp
1000 v of electric potential

### x-ray current are measured in

mA
electric current
m=1/1,000 or .001

### Fast moving particles

particles with high kinetic energy

1/1000 if a rem

### rem

x-rays
any type of radiation that is capable of removing an orbital electron from the atom with which it interacts

cosmic rays

### Human evolution has been influenced by

largest source of natural environmental radiation
a radioactive gas that is produced by the natural radioactive decay of uranium
emits alpha particles, radiation to lung only, non penetrating

60 mrem/year
largest- diagnostic x-rays (catscan)
nuclear power, research applications industrial sources, consumer items

electrons

### Crookes Tube

partially evacuated glass tube
cathode rays experimented with by sir William crookes
1870's-1880's

### Electromagnetic energy

least familiar level but the most important in x-ray
radiowaves, microwaves, ultraviolet rays, infared, visable light

visible light radiated by the sun

### Theory of relativity or Mass-Energy formula

E=mc^2 (squared)
energy= mass x speed of light in a vacum tube squared

### Albert Einstein

mass-energy equivalence theory

energy emitted and transferred through space
the transfer of energy

matter that intercepts radiation and absorbs part or all of it

### negative ion

the electron from ionization

### positive ion

the remaining atom from ionization

### Electrical energy

the work that can be done when an electron moves through an electric potential difference (voltage)

### Thermal energy (heat)

the energy of motion at the molecular level
faster= increased thermal energy

### Nuclear energy

energy that is contained within the nucleus of an atom

### Biochemistry

chemical energy at the molecular level

### Ion Pair

orbital electron and the atom from which it was seperated from

### Mechanics

a segment of physics that deals with objects at rest (statics) and objects in motion (dynamics)

### When one si working on problems on reporting answers

the same system of units must always be used

magnitude, unit
100 cm

mass
length
time

### Second

standard unit of time
rotation of the earth on its axis, solar day

### Secondary quantities

derrived quantities
because they are derived from a combination of one or more of the three basic quantities

energy, power, work, momentum, force, velocity, acceleration

### Special quantities

designed to support measurement in specialized areas of science and technology

### Length

distance between two lines engraved on a platinum - iridium bar kept at the international Bureau of weights and measurements in paris - 1 meter

speed of light

kg = mass

newton
pound

### kg is the mass of...

1,000 cm^3 of water at 4 degrees C

### Physics

the study of interactions of mater and energy in all thier diverse forms

### Average velocity equation

average velocity= final velocity + initial velocity
over 2 (divided by )

_
V = Vf + Va
------------
2

c=3 x 10^8 m/s

velocity
Acceleration

Example: