X-ray Machine, X-ray Quality, and Attenuation

Question 1

__ ____- Flow of electrons through a wire or circuit.

- Source of energy usually 110 or ___ Volts

Answer 1

Electric Current

220

Question 2

Electrons flow in one direction

Answer 2

Direct Current

Question 3

Electrons travel in one direction, stop and then reverse and go in the opposite direction.

Answer 3

Alternating Current

Question 4

Electricity cylces in an __ ___- the curve above and below a horizontal line

Answer 4

Alternating Current

Question 5

_ ___ necessary for production of x-rays in the x-ray tube

• ___ Circuit
• High __ Circuit

Answer 5

2 Circuits
Filament Circuit
High Voltage Circuit

Question 6

Step Down Transformer

Answer 6

Heats the filament circuit
Controlled by Milliamperage (mA)
Fewer turns in second coil than primary coil
Decreases voltage from 110 to 3-5 volts

Question 7

Step-up Transformer

Answer 7

Controls the high voltage circuit
Controlled by Kilovoltage
More turns in the secondary coil than the primary coil
Changes 110 volts to 65,000-100,000 volts

Question 8

Gives the ability to alter kilovotage of the x-ray machine

A single coil around a iron core serves as the primary and secondary coil

Answer 8

Auto Transformer

Question 9

MA (Milliamperage) determines

Why does it effect Quantity?

Answer 9

the # of photons in a beam

Question 10

kVp (Kilovolt Peak) determines

kVp also influences the Quantity why?

Answer 10

the energy of each photon, ie Quality

Also influences quantity because

Question 11

Distance of the Xray beam is the

Answer 11

size of the beam

Question 12

Rate of the xray is the

Answer 12

exposure time ie ///// Quantity. More time more xrays

Question 13

Does exposure influence Quantity

Answer 13

Yes. Why? Because
A longer exposure time produces more xrays.
An increase increase in xrays produces a more intense beam

Question 14

**mA + kVp+ Distance + Rate together =

Answer 14

Beam Intensity

Question 15

Relationship between exposure time and mA

Answer 15

mA required for a given exposure time is inversely proportional to the exposure time
- HIGHER mA requires less exposure time

Question 16

What is the equation to represent source-film distance effects on intensity

Answer 16

Inverse square law
Original mAs (time) /
New mAs (time)

=
Original SFD^2/
New SFD^2

Question 17

Short
Great penetration
High energy
High frequency
Go through

Answer 17

Best xrays

Question 18

Long
Low penetration
Low energy
Low frequency
Absorbed

Answer 18

bad xray

Question 19

Filtration of xrays

Answer 19

Located in tubehead
aluminum selectively absorbes out useless lower energy photons

Half Value Layer-
the thickness of absorbing material (usually aluminum) necessary to reduce x-ray intensity by half its original value

Question 20

Controls the size and shape of beam produced
Metal cylinder or lead washer
Shapes the x-ray beam
Round BID
Rectangular BID

Answer 20

Collimation

Question 21

Restricts the size of the primary beam

Answer 21

Collimation

Question 22

penetrating x-ray beam produced at the tungsten target of the anode that exits at the tubehead.
AKA- Useful Beam

Answer 22

Primary Radiation

Question 23

created when the primary beam interacts with matter.
Includes soft tissue of head, bones of skull, and teeth.
Scatter Radiation- Form of secondary radiation resulting from an x-ray photon that has been deflected from its path by the interaction with matter.

Answer 23

Secondary Radiation

Question 24

Secondary Radiation
A
B
C

Answer 24

Pass through
Absorbed
Scatter

Question 25

Secondary Radiation __ ___ with no interaction producing dark areas on film (radiolucent)
-Examples- soft tissue, pulp, PDL

Answer 25

pass through

Question 26

transfer of energy from x-ray photon to the atoms of matter through which the x-ray passes (approximately 30% of interactions with matter)
Produce light or white areas on film
Examples- cortical bone, enamel, metallic restorations

Answer 26

Photoelectric Effect
Absorbed Completely
Radiopaque

Question 27

photon strikes a loosely bound outer shell electron of matter, and ejects is from orbit (ionization)
the x-ray photon loses energy and continues in another direction (including backwards)
If reaches the film it produces fog

scattered x-ray deflected from its passage through matter (approximately 62% of interactions with matter)

Answer 27

Compton scatter

Question 28

Interaction of x-rays with patient

low energy photon has its path altered by matter and changes directions. (approximately 8% of interactions with matter)
X-ray photon undergoes change in direction without change in energy

Answer 28

Coherent Scatter

Question 29

reduction in the intensity of the x-ray beam as it transverses dental tissues./ Absorption

High absorption of x-ray photons=____________
Low asborption of x-ray photons =

Answer 29

Attenuation

radiopaque areas on film- bone

Radiolucent areas on film-air

Question 30

Factors Affecting Absorption

Answer 30

Wavelength:The energy of the xray photon

Density of Material

Thickness of Material

Atomic Number of Material:
Higher atomic number= greater absorption
- Aluminum=13
-Copper = 29
- Lead= 82