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

Heat Transfer

Conduction
Convection
Radiation

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

Radiation

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

F to C

C= 5/9 (F-32)

C to F

F= 9/5 (C+32)

C to K

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 +

unit of radiation, absorbed dose

Gy a

(R) Roentgen
Unit of radiation exposure or intenstiy

Sv

rem
occupational radiation exposure

Bq

Curie
radioactivity

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

Gravity in outer space = ______

0

The value of acceleration due to gravity on the moon is about ___ that on the earth

1/6

Weight formula

Wt=mg
Weigh= mass x gravity

The acceleration of gravity on earth

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

SI unit of force

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

Found that ________ were occuring in radiologists at a much higher rate

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

mrem

1/1000 if a rem

rem

radiation equivalent man

ionizing radiation

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

natural environmental radiation

cosmic rays
terrestrial radiation
internally deposited radionuclides

Human evolution has been influenced by

natural environmental radiation , ionizing radiation

Radon

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

man made radiation

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

Cathode rays

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

Electromagnetic Radiation

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

Radiation

energy emitted and transferred through space
the transfer of energy

exposed/ irradiated

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

Two parts of measurements

magnitude, unit
100 cm

3 measurable quantites

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

exposure, dose, equivalent dose, radioactivity

Length

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

Meter is based on

speed of light

Mass

kg = mass

unit of weight

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

Constant velocity of light

c=3 x 10^8 m/s

The motion of an object=

velocity
Acceleration

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