DRXY ROENT PRELIMINARY EXAMINATIONS

Wilhelm Conrad Roentgen

• Experimented in Bavaria (Germany) on November 8, 1895

• Experiment with a vacuum tube called Crooke’s tube

DR. FRIEDRICH OTTO WALKHOFF

German physicist, the first to expose a prototype of a dental radiograph

DR. WILLIAM H. ROLLINS

• “dentistry’s forgotten man”

• While working with x-rays in 1898, he suffered severe burns to his hand

• The first advocate for the science of radiation protection. “father of radiation protection”

DR. WILLIAM J. MORTON

• Known to have taken radiograph on skulls very early

• The first to discover impacted teeth radiographically

DR. CHARLES EDMUND KELLS JR.

The first to put the radiograph to practice use in dentistry

DR. WILLIAM D. COOLIDGE

• American physicist and engineer who worked for the General Electric Company

• Introduced the hot cathode tube (Coolidge tube)

DR. HOWARD R. RAPER

• First dental educator to hold the title of “Professor of Radiology”

• Wrote the first dental radiology textbook (Elementary and Dental Radiology)

GORDON FITZGERALD

He introduced the long cone paralleling technique in 1947

FRANKLIN McCORMACK

He was the first to put the paralleling technique into use in intraoral dental radiography

ROENTGENOLOGY

Studies technique and interpretation

Technique

studies how to take radiograph; how to properly position the film; how to properly orient the radiation as it hits the film and the tooth

Interpretation

describing what you see in the image that has formed; analyzing the radiograph that were taken; interpreting the findings

LED Apron and Thyroid Collar

What do we need to protect ourselves from radiation: _________(will protect the self from radiation) and ____________ (will protect the thyroid gland)

“graphy”

Means technique

Intraoral

the film is positioned inside the mouth • Example: periapical, occlusal, bitewing

Extraoral

the film is outside the mouth

ORAL RADIOLOGY

• The interpretation of radiographic images

• How to properly describe the lesions

RADIOGRAPHIC SHADOWS

• The amount of the x-ray beam is attenuated by an object determines the radiodensity of the shadows

• Can penetrate objects, high EMR

Radiopaque

• white shadows

• dense

• amalgam filling, enamel

Radiolucent

• black shadows

• not so dense

• ex, tissue spaces, sinsues, pulp

type of material, thickness of density etc

Shadow density is affected by

Density

• In radiography, it is defined as the degree of darkness of film

• More x-rays reaching the film, darker

Metal -

radiopaque

Plastic -

Radiolucent

Radiographs

• 2D representation of 3D objects

• 2D images have limited information

CONTRAST

Usual difference between the various black, white, and grey shadows

IMAGE QUALITY

Definition, geometric accuracy, and detail of the final image

RADIATION PHYSICS

• Atom: basic building blocks of matter vs Cell: basic unit of life

Atom is composed of 3 components

• electron (-)

• proton (+)

• neutron (uncharged)

ATOMS

• basic building blocks of matter

• proton and neutron: in the middle; makes up the nucleus

• surrounding the nucleus is the electron

ISOTOPES

• atoms with the same atomic number (Z) but with different atomic mass numbers (A) and hence different numbers of neutrons (N)

• stable form of an element

atomic number -

number of protons

atomic mass -

number of protons + number of neturons

RADIOISOTOPES

Unstable form of an element that emit radiation to transform into a more stable form

Radioisotopes

Electrons move in a determined circular or elliptical shell

Excitation

the electron is displaced (did not leave the atom) from one shell to another

Ionization

incoming electron (moving) would travel and replace an electron (shell). An electron was dislodged (in K shell) and this will create radiation

Heat producing collisions

heat is produced

X-ray producing collisions

X-ray is produced

HEAT PRODUCING COLLISIONS

the incoming electron is deflected by the cloud of outer-shell tungsten electrons, with a loss of small energy, in the form of heat

X-RAY PRODUCING COLLISIONS

the incoming electron penetrates the outer electron shells and passes close to the nucleus of the tungsten atom

APPEARANCE

x-rays are invisible and cannot be detected by any of our senses

MASS

x-rays have no mass or weight

CHARGE

X-rays have no charge

SPEED

X-rays travel at the speed of light

WAVELENGTH

X-rays travels in waves and have short wavelengths with high frequency

PATH OF TRAVEL

X-rays travel in straight lines and can be deflected or scattered

FOCUSING CAPABILITY

X-rays cannot be focused at one point and always diverge from a point

PENETRATING POWER

• X-rays can penetrate liquid, solids, and gases

• The composition of the substance determines whether x-rays penetrate or pass through or are absorbed

ABSORPTION

• X-rays are absorbed by matter

• The absorption depends on the atomic structure of matter and the wavelength of the x-ray

IONIZATION CAPABILITY

• X-rays interact with materials they penetrate and cause ionization (dislodgement of electron)

FLUORESCENCE CAPABILTY

• X-rays can cause certain substances to fluoresce, or emit radiation in longer wavelengths (e.g. visible light)

EFFECT ON FILM

X-rays can produce an image in photographic film

EFFECT ON LIVING TISSUES

X-rays cause biologic changes in living cells

EXTENSION ARM

• Houses the electrical wires that extend from the control panel to the tubehead

• Suspends the x-ray tubehead

TUBEHEAD

Where X-ray is being generated

METAL HOUSING

• metal body of the tubehead;

• surrounds the x-ray tube and transformers

• filled with oil, protects the x-ray tube

INSULATING OIL

• oil that surrounds the x-ray tube and transformers inside the tubehead

• prevents overheating by absorbing the heat created by the production of x-rays

TUBEHEAD SEAL

• Aluminum or leaded glass covering of the tubehead that permits the exit of radiation from the tubehead

X-RAY TUBE

Heart of the x-ray generating system

TRANSFORMER

• Device that alters the voltage of incoming electricity

• Increase or decrease the voltage in an electrical circuit

ALUMINUM DISKS

• Sheets of 0.5 mm thick aluminum placed in the path of the x-ray beam

• Filter out the non-penetrating longer wavelength x-rays

LEAD COLLIMINATOR

• Would prevent radiation from passing through

• prevent spread of radiation

POSITION INDICATING DEVICE (PID)

• Open-ended, lead lined cylinder that extends from the opening of metal housing of the tubehead

• aims and shapes the x-ray beam

• 8,12,16 inches long

X-RAY TUBE

• Heart of x-ray

• It is where the radiation is being produced

CATHODE

• role: to produce the electrons

• negatively charged, supplies the electrons necessary to generate the x-rays

Tungsten filament

responsible for producing the electron; tungsten has a high melting point; produces electrons when heated

ANODE

positively charged

Tungsten target

converts the electron to x ray protons; tungsten has a high melting point; converts the kinetic energy of the electrons generated from the filament into x-ray photons

Copper Stem

thermal conductor and dissipates heat

TUNGSTEN

• high atomic number, more efficient for production of x-ray

• high melting point; 99% of kinetic energy is converted to heat

• low vapour pressure, precludes compromising the vacuum in the tube at high operating temperature

X-RAY GENERATING APPARATUS

• electricity and electric current

• electrical circuits

• transformers

Electricity

energy that is used to make x-rays

Electrical energy

consists of a flow of electrons through a conductor

Electric current

flow of electrons

Amperage

measurement of the number of electrons moving through a conductor

Amperes or milliamperes

it is the measurement of current

Voltage

measurement of electrical force that causes electrons to move from a negative pole to a positive one

Volts or kilovolts

measurement of voltage

Milliamperage (mA) adjustment

controls the amperage or the no. of electrons passing through the cathode filament by increasing or decreasing it

Kilovoltage peak (kVp) adjustment

controls the current passing from the cathode to the anode

Circuit

path of electric current. Two electrical circuits are used in the production of x-rays

Filament circuit (low voltage)

uses 3 to 5 volts. Controlled by the milliamperage

High voltage circuit

used 65,000 to 1000,000 volts controlled by the kilovoltage settings

GENERAL RAD. (BREMSSTRAHLUNG)

• radiation produced when the speeding electrons slow down because of their interactions with the tungsten target in the anode

• focus on the nucleus

Direct hit

Produced by the sudden stopping or braking of high speed electrons at a target

Near miss

Electron doesn’t hit the nucleus

CHARACTERISTIC RAD

Produced when a high-speed electron dislodges, an inner shell electron from the tungsten atom and causes ionization of that atom

PRIMARY

refers to the penetrating x-ray beam that is produced at the target of the anode and exits the tubehead

SECONDARY

refers to x-radiation that is created when the primary beam interacts with matter

SCATTER

Form of secondary radiation that deflects after it hits matter

RADIOBIOLOGY

It is the branch of biology concerned with the effects of ionizing radiation on living systems

Cosmic radiation

from the sun & outer space

Terrestrial radiation

earth’s crust

Internal radiation

sources of the human body

ARTIFICIAL (MAN MADE)

• Accounts for about 15% of the total radiation burden

• 97% of all man-made radiation is due to diagnostic medical (and dental exposures)

1895

Wilhelm Conrad Roentgen announces discovery of X-rays

1896

(4 months later) reports of skin effects in x-ray researches

1902

First cases of radiation induced skin cancer reported

1906

• Pattern for differential radiosensitivity of tissues was discovered

• they discovered that some cells are sensitive to radiation

Radiosensitive

cells are killed easily by radiation