Radiology Chapter’s 2, 3. & 4 By Garland Fisher Electromagnetic spectrum Unique abilities Some rays visible some are not Penetrates matter Produces latent.

Radiology

Chapter’s 2, 3. & 4

By Garland Fisher

Electromagnetic spectrum Unique abilities

Some rays visible some are not

Penetrates matter Produces latent image

Produces fluorescence Light bulb

Produces ionization of matter Change matter

Matter

Anything that occupies space and has mass

Matter can be altered by energy

Fundamental unit of matter is the Atom

Desk Chair Computer Tissue Muscle Teeth Bone Your Patient

Atom

An atom is the smallest unit of an element, it consist of a positively charged protons found in the nucleus. Negatively charge electrons that orbit around the nucleus.

Neutron

Proton

Electron

Electrons

Nucleus(Dense core that occupies very little space)

Protons Subatomic particles and

positively charged

Neutrons Subatomic particles and

has no charge

Nuclear Composition

Equal number of protons and electrons form a stable atom.

The number of protons and neutrons equals the atomic weight.

Force will knock an electron out of their orbit. X-radiation Electromagnetic energy

Is this Atom stable or unstable?

Ionization(production of ions)

Converting atoms into ions. To produce ions a force or a collision

such as x-radiation or electromagnetic energy must eject an electron out from its orbit. Thus making the atom unstable.

Spontaneous release excess energy in the form of wave or particles.

ION

Electrostatic ForceBinding energy holds electrons in their orbits(Example: sun and the planets)

There are seven shells an atom can have they are k, l, m, n, o, p, and q.

K-shell has the highest energy and the strongest binding energy

Nucleus

q

p

o

nm

l

k

Atoms into ions

Positive ions are ionized atoms.

An ionized atom has been interrupted by some force: X-radiation Electromagnetic energy

Negative ions are electrons out of orbit or unstable structures.

This ejected ion will speed off to interact with other atoms.

When they interact or collide it sets off a chain reaction and in turn will eject other electrons until the energy dissipates.

Elements Elements

Substances made up of only one type of Atom

Molecule

Molecule Two or more Atoms

make up a molecule

Two Hydrogen and one Oxygen = Water

Bonded together by electrons on the outer most shells

Ionizing Radiation(all radiation cause biological changes)

Particulate Responsible for

radioactivity

Radioactivity is when atoms spontaneously disintegrate or decay. Power plant Atomic bomb

Electromagnetic Series of wave like

energies with no mass some high energy some low energy

Visible and invisible Man made or natural

occurring

Electromagnetic Energy Made up of both wave and particle that

travel in a straight line X-ray = bundle of energy, is termed, x-ray

photon which has no mass no charge and travels at the speed of light (186,000 MPS)

X-ray photon is what interacts with matter (your patient)

Examples of electromagnetic radiation and there wave like patterns

Less energy

More energy

Electromagnetic Energy

Wavelength Distance between the

crest of the wave to the next wave

Frequency Refers to the number of

wavelength that pass a given point in a certain amount of time. We can adjust the frequency by kilovoltage

Voltage

Measurement of electrical force that cause electrons to move from a negative pole to a positive one (Strength)

Dental x-ray units require a high level of electrical potential

Kilo-Voltage Peak(KVp)

Kilovoltage controls the level of penetration Shorter wavelength =

more penetrating High frequency = more penetrating Longer wavelength =

less penetrating Low frequency the =

penetrating

Kilovoltage Kilo = 1000 Volatage = volts 110 or 220 Higher voltage means

greater energies Dental radiographs require

65 to 100 kilovolts Higher KVp should be used

when area is dense or thick Adjust KVp on individual

diagnostic needs Overall QUALITY of

primary beam

Amperage

Measurement of electrons moving through a conductor

Current is measured in amperes

Milliamperes (mA) Milliampere

Milli = 1/1000 Ampere = Electrical

current NOT voltage mA settings

7, 10, and 15 Thermionic emissions

Higher the setting increases temperature resulting in some electrons being ejected out of their orbit.

Ampere allows electrical current to flow thru a filament which results in a cloud of electrons

Depending on mA setting will depend on the QUANTITY of x-rays produced

Milliamperes-Seconds

Exposure time Interval of time in which

photons are being produced (.117 secs)

Longer time = more photons

High mA = more photons

Both mA and exposure time both have a direct influence on the number of electrons produced

If we produce to many photons our dental film will be dark or black

Radiographic Density(Degree of darkness or blackness of an x-ray.)

Density Amount of radiation

reaching the film KV or mA

Distance from the x-ray tube to the patient

Patient thickness (Density)

Developing conditions

The more photons that strike the film the more dense (black) the radiograph will appear

Tubehead

Cathode Negative electrode

consist of tungsten filament held in a cup shaped holder made of molybdenum

Negative = electrons, therefore electrons are created to produce photons

*

Electrons held in place

Tubehead

Anode Positive electrode consist

of a wafer thin tungsten plate embedded in a solid copper rod

Positive = collision = photons

*

Collision produced photons (indicated in red)

TransformersThree types are used in production of x-rays

Step down decreases the voltage from the incoming 110 or

220 to three to five volts required Step up

Increases the voltage to 65,000 to 100,000 volts required

Autotransformer Compensator

Inside the Tubehead

This is What Happens Electricity excites the filament at 3-5 volts, creating thermionic

emissions, a release of electrons from the tungsten filament when heated, this cloud of electrons stay in place until the exposure button is pushed. The high voltage circuit is activated. The electrons produce are accelerated across the x-ray tube to the anode. The molybdenum cup helps to direct the electrons to the tungsten target. When the electrons strike the tungsten target their energy of motion or kinetic energy is converted to x-ray energy and heat. More heat is created that x-rays and is dissipated through the copper stem and absorbed by the insulating oil. X-rays are produce in all direction only a few will escape through the unleaded portion of the tube. Those x-rays will be directed to the aluminum filter, which will remove the long waves. The collimator will focus the remaining short waves and travel down the lead lined PID and exit the tubehead

Production of radiation(not all produce the same in the tube head)

General radiation AKA braking radiation

An electron passes near the nucleus and is deflected by the positively charge nucleus

Once deflected this kinetic energy is converted into photons

Add photo

Bremsstrahlung German

(braking radiation)

Production of radiation(not all produce the same in the tube head)

Characteristic radiation

Electron that has been deflected continues to travel ejecting other electrons out of orbit until they loose their kinetic energy Energy in motion