Image Production - Module 1 and 2

Electricity

Form of energy created by active electrons and other subatomic particles in motion

Current

Flow of electric charge

Amperes

SI unit of electric charge OR the unit of measure for electron flow

Milliampere

Measure of x-ray tube current - 1/1000 of Ampere

Volt

Unit of electric potential & Potential difference - potential energy if allowed to flow

Kilovolt

1000 volts

Watt

Unit of power - 1Amp that flows through an electric potential of 1 Volt - the rate of conversion with respect to time

Kilowatt

Measure of the rate of energy usage - 1kW = 1000 watts

List primary factors affecting radiographic image

1. mA

2. S

3. mAs

4. kV

5. SID

mAs

exposure factor that regulates the intensity of radiation emitted by the xray tube

S = time in seconds

kV

1000 Volts - exposure factor used to influence radiographic contrast, penetration of tissues, and directly influences radiographic image quality

SID

source to image distance

List the primary factors affecting image qualities

1. Radiographic density

2. Radiographic contrast - image and subject contrast

3. Spatial resolution or Recorded Detail

Radiographic density

The amount of blackness on the radiograph

Radiographic contrast

Differences in optical density of adjacent structures

High contrast = black and white

Low contrast = more shades of gray

Spatial resolution

The ability to image small objects that have high subject contrast

Recite the law of conservation of energy

Energy can neither be created nor destroyed - only converted from one form of energy to another

List the 4 conditions needed for x-ray production

1. Source of electrons

2. Acceleration of electrons (done with kVp)

3. Focusing of electrons (focusing cup)

4. Sudden deceleration of electrons at the target

Draw and label the following emission spectra - discrete, continuous, and combination

Velocity

Distance/Time

Acceleration

(v2 - v1)/t

Weight

mass x gravity

Mass

weight/gravity

Work

force x distance

Power

work/time

- measured in joule/second = watt or horsepower

Newton's Laws

1. Inertia

2. Force - (mass x acceleration)

3. Every action has an equal and opposite reaction

Inertia definition

A body at rest stays at rest, and a body in motion stays in motion, unless acted upon by an external force

Force

Mass x Acceleration

SI

international system of units - scientific method of expressing the magnitudes or quantities of important natural phenomena

BGS - British gravitational system

uses force as a fundamental dimension instead of mass

outer shells of atom have more potential to do ____

work

inner shells

more tightly bound

binding energy

the strength which holds an electron to its shell

octet rule

8 electrons make the outermost shell stable

Orbital shells formula

2N^2

Atomic number

# of protons and electrons in an atom

Atomic mass

# of protons and neutrons

Isotopes

atoms with the same atomic number, but differ in neutrons

(basis of nuclear medicine)

Group 8 does not combine because ______

octet rule - they are stable because they have 8 electrons in outer shell

elements on the periodic table are arranged in ____ according to their _____ _____ from 1 - 103

row, atomic number

Valence #

# of electrons in outermost shell

Oxidation number

how many e- to get to 8 e- in outermost electron

you have 6 and need 2

oxidation # is -2 because e- is negative (-)

Matter

Anything that occupies space and has inertia - usually impure and indefinite in composition

Ionization definition

The process of charging atoms by the addition or removal of electrons

Ion

is a charged atom - has a excess or deficiency of electrons

Identify the 6 types of ionization

1. Exposure of matter to x-rays or gamma rays

2. Exposure of matter to a stream of electrons

3. Spontaneous decay of radionuclides

4. Exposure of certain chemicals to light

5. Chemical ionization

6. Thermionic emission

Exposure off matter to x-rays or gamma rays

we do this with every exposure we make

Exposure of matter to a stream of electrons

this is what happens in the x-ray tube during the exposure resulting in the creation of x-rays

Spontaneous decay of radionuclides

This is the premise of nuclear medicine

Exposure of certain chemicals to light

used in radiology for electronic imaging such as in fluoroscopy, direct capture imaging and computed radiology

Chemical ionization

electrolysis - ions separate into (-) and (+) and migrate to positive or negative elecrodes

Thermionic emission

Electrons are released from outer orbital shells through heating

happens at the cathode end of the x-ray tube (filament)

List THE 4 conditions required to produce x-rays

1. Source of electrons

2. Acceleration of electrons - (done with kVp)

3. Focusing of electrons

4. Sudden deceleration (hitting tungsten/anode)

Sudden deceleration of electrons at the target converts kinetic energy into 2 other forms

Heat - 99%

Radiation - 1%

Formula for energy cannot be created or destroyed, it changes forms

[E=mc^2]

How is heat made

projectile electrons interact with outer shells - not enough to excite it, no ionization occurs

What range of kVp is mostly Bremsstrahlung

30-150kVp

Average energy of Brems photon

1/3 of kVp

True or False - Bremsstrahlung produces many different photon energies (continuous spectrum of energy)

True

true or false - characteristic radiation is a preferred type of photon

true

there are only __ charactersic photon energies from a tungsten target

15

Binding energy of tungsten target K-shell

69.5 keV

is there a difference between the 2 types of x-rays at the same energy levels

no - just how they are produced