oral radiology: xray production

Wilhelm Rontgen revolutionized

diganostic resources in the medical and dental fields

Wilhelm Rontgen did research with

cathode rays and special screens that glowed when exposed

Wilhelm Rontgen experimented with vacuum tubes, where he noticed

greenish fluorescence on plates that were away from the tube

when Wilhelm Rontgen replaced the plates with photographic films, what was permanently recorded

shadows of the image

Wilhelm Rontgen first xray was of what

wife's hand bones

Dr. Otto Walkhoff was a pioneer of

dental radiology

Dr. Otto Walkhoff placed what in his mouth and exposed it for 25 mins

photographic glass plate

atom

smallest particle of an element having the chemical properties of the element

Bohr model of the atom

Model of the atom with a positive nucleus and electrons orbiting in energy levels

atomic nucleus composition

protons (+) and neutrons

orbital composition

electrons (-)

proton and neutron size

1 amu

electron size

0.0005 amu

atomic number

# of protons

atomic number determines what

what element it is

atomic number is fundamental for determining

element's chemical and physical properties

atomic mass

# of protons and neutrons

atomic mass determines

stability of element

# of electrons determines

charge of atom

ion

charged particle

ionization

creation of an ion

radiation

transmission of energy through space and matter in the form of waves and particles

ionizing radiation

high-energy radiation, capable of producing ions

radioactivity

spontaneous nuclear disintegration process of a molecule to acquire a more stable form

Particulate radiation

electrically charged (except for neutrons) tiny particles of matter that possess mass and travel in straight lines and at high speeds

electromagnetic radiation

a form of energy that exhibits wavelike behavior as it travels through space, with no mass

Electromagnetic radiation is generated when

the velocity of an electrically charged particle is altered

only higher energy particles can cause

ionization

two theories that can describe the properties of electromagnetic radiation

1. quantum theory

2. wave theory

quantum theory

small discrete bundles of energy (photons) that travels at the speed of light and contains a specfic amount of energy

wave theory

transverse waves of oscillating electric and magnetic fields, perpendicular to each other and the direction of travel, moving at the speed of light in a vacuum

xrays can

ionize matter

wavelength definition

distance between successive crests of a wave

frequency definition

number of waves that pass a fixed point in a given amount of time

wavelength unit

meters

frequency unit

hertz

the higher the frequency, the ____ the wavelength

shorter

non-ionizing radiation examples

1. radio waves

2. microwaves

3. infrared

4. visible

ionizing radiation examples

1. ultraviolet

2. xray

3. gamma ray

alpha particle

2 protons + 2 neutrons

beta particles (cathode rays)

electrons

Radioactivity is usually associated with

protons and neurons

higher the freqency, the ___ the energy

higher

the shorter the wavelengths, the ___ the energy

higher

xrays are a type of

electromagnetic radiation

xrays have no

mass and electrical charge

xrays are at the speed of

light

xrays have a ___ wavelength

short

xrays have an energy of

10^4 to 10^5 eV

xrays direction of propagation

straight line but can be deflected or scattered

do xrays travel parallel or diverge

diverge

xrays have effects on

imaging films and living beings

contents of xrays tube

1. cathode (-)

2. andoe (+)

3. evacuated glass envelope

cathode of xray tube is made of

1. tungsten filament

2. concave molydenium bowl

anode of xray tube is made of

1. tungsten

2. copper block

function of tungsten filament

source of electrons

function of concave molydenium bowl

focusing cup

function of tungsten

focal spot

function of copper block

thermal conductor

contents of evacuated glass envelope

lead glass with a window of non-lead glass

electricity definition

energy used to produce xrays

electric current definition

flow of electrons flowing through a conductor

circuits definition

path through which an electric current goes into the machine

transformers definition

responsible for increasing or decreasing the voltage electric current

steps of xrays production

1. electricity on the plug

2. current in the tungsten filament

3. heating the filament

4. fire button

5. high voltage circuit

6. upon reaching the tungsten target, kinetic energy is lost through xrays and heat

heating the filament creates

thermionic emission (release of electrons from a heated material's surface)

number of volts of current running in tungsten filament

3-10V

amperage/milliamperage (mA)

controls the electrical current/ number of electrons moving within the filament

kilovoltage (kv) / kilovolt peak (kVp)

maximum voltage that enables the movement of electrons from the cathode to the anode

higher the mA, the ___ electrons flowing within the filament

more

lower the mA, the ___ electrons flowing within the filament

less

the higher the kV, the ____ the velocity of the electrons

higher

the lower the kV, the ____ the velocity of the electrons

lower

2 types of xrays collisions

1. result in heat generation

2. result in xray production

when electrons get close to (stable) tungsten particles in outer shells they get deflected and lose energy in the form of ___

heat

when electrons hit (stable) tungsten particles in outer shells, ___ atoms get deflected and produce ___

both, heat

The closer the orbit is to the nucleus, the higher the

binding energy

The difference between heat production or xray production collisions

xray production collisions happen closer to the nucleus

Braking radiation (Bremsstrahlung) characteristics

1. 70% of X-rays produced

2. no collision with other electrons

3. broad spectrum of energy

4. keeps colliding with other atoms

another type of braking radiation characteristics

1. rare

2. electrons hits the nucleus of an atom

3. all kinetic energy is converted into high-energy x-ray photon

characteristic radiation characteristics

1. displacement of an electron of the inner shells

2. lesser amount of x-ray photons

3. requires energy greater than 70 kVp

4. electrons change of positions between orbitals

in characteristic radiation what is the result of electrons changing positions between orbitals

instability

when outer shell electrons move to inner shells in characteristic radiation what is lost

internal energy

primary radiation definition

xray beam produced in the anode, leaving the xray tube

secondary radiation definition

radiation produced by photons interacting with matter

scattering of radiation definition

deflected in all directions after interacting with the matter

types of xray interactions

1. no interaction

2. complete absorption/photoelectric absorption

3. compton scattering of the photons

4. coherent scattering of the photons

no interaction xray

xray photon passes through the patient unchanged and leaves atom unchanged

no interaction xray are responsible for producing ___

densities

absorption of energy/photoelectric effect xray interation definition

xray photon hits an electron of any orbital and photon is completely absorbed

in absorption of energy/photoelectric effect xray interation, there is atom ionization due to

ejected photoelectron - atom lost an electron

absorption of energy/photoelectric effect and compton scattering contribute to dangerous xrays due to what

ionization of the atom

compton scattering xray interaction definition

scattering with ionization where the photon loses some of its energy, is deflected, and continues with less energy

ejected electron is called

compton electron

coherent scattering xray interaction definition

photon interacts with a whole atom, the atom becomes momentarily excited and generates another photon with the same energy - no changes to the atom at the end