Unit 2 Dental X-Ray machines & the production of X-rays

What is the Components Of The Intraoral Dental X-ray

Machine

• Extension arm

• Control panel

• Tubehead

Control Panel - Progoney

• kV selector (60 or 70)

• exposure timer

• manual override

• mA indicator

• exposure indicator

• exposure button

Position Indicating Devices (PIDs

The PID is more commonly known as the “cone”.

PIDs come in:

-different lengths (usually 20, 30 or 40 cm)

-different shapes (round or rectangular

The x-rays exit the tubehead through the PID.

What is Voltage and what does it measure?

 a unit of measurement; measures the force that causes electrons to move from a negative to a positive pole

 It’s the power behind the electrons to move from a negative to a positive pole.

What is Amperage and what does it measure?

 a unit of measurement; measures the number of electrons flowing through a conductor

 This means number of x-rays

Exposure time

• also measures the number of x-rays/electrons. More time, more x-rays Quantity

• exposure time maybe measured in: impulses (30 impulses)

decimals

(.50 seconds)

fractions

(1/2 second

→ there are 60 impulses in a second

What is the Deadman Timer?

a safety feature:

 if the finger does not continue to press the button, there is no

exposure

 Some machines have a visual indicator that exposure is

incomplete – others do not

Safety guidlines

The radiographer must stand behind a barrier or have 3 meters from

the source of radiation

X-ray tube

X-ray tube - Leaded glass housing

 unleaded window

 Vacuum

X-ray - Cathode

 tungsten filament

 molybdenum focusing cup

 negative charge

Anode

 tungsten target/focal spot

 copper stem

 positive charge

The Production of Dental X-ray

 heat (99%) and x-rays (1%). the copper stem of the anode.

 X-rays are emitted from the focal spot in all directions.

Tungsten Target

A small number of x-rays escape the tube through the?

Unleaded window

Where does The electric current flows?

the cathode of the x-ray tube

What is heated to produce electrons?

tungsten filament

mA controls what?

the amount produced

Electrons “boil off” the filament and an electron cloud is?

formed, this process is called thermionic emission

The electron cloud ____ in the molybdenum focusing

cup until the radiographer is ready to make an exposure.

stays ready

what happens next when the Exposure button is pressed?

The kilovoltage (force) kicks in and sends the electrons flying from the cathode to the anode

When the electrons strike the target on the anode, the energy

is converted into?

heat (99%) and x-rays (1%)

The heat is carried away by the ____ of the anode.

copper stem

X-rays are emitted from the ____ in all directions.

Tungsten Target

focal spot

where does the x-ray goes through?

aluminum filter

The filter removes the ____. Soft x-rays are less

penetrating and not add to image quality, they only expose the

patient

soft x-rays

The aluminum filter allows only the?

more penetrating x-rays to pass through

After leaving the filter, the size and shape of the beam is

determined by the?

lead collimator (round or rectangular)

The x-rays then exit where?

the tubehead through the PID

What are the types of radiation?

Primary Radiation and Secodary/Scatter Radiation

Primary radiation

 Also known as the Primary or Central Beam.

 The primary beam is produced at the ANODE of the x-ray

tube.

Secondary/Scatter Radiation

 created when x-ray energy is absorbed or deflected and then re-released.

 Is less penetrating than primary radiation