Chapter 2

What happens after x-ray exits tube head?

-X-rays can pass through patient with out any interaction -Can be completely absorbed by patient -Can be scattered

Involves an x-ray photon that has its path altered by matter

Coherent/Unmodified scatter

At the atomic level _________ effect accounts for most of the scatter radiation

Compton

It is the ejected electron in compton scatter and it also has a negative charge

Compton electron or recoil electron

An x-ray photon collides with a loosely bound outer shell electron and gives up part of its energy to eject electron from its orbit

Compton scatter

The __________ contains an on-off switch and an indicator light, and control devices (time, kilo-voltage, and milliamperage selectors) to regulate the x-ray beam

Control panel

What are the 3 visible component parts of the x-ray machine

Control panel,extension arm, and tubehead

What is the purpose of the anode?

Convert electrons into x-ray photons

Functions to dissipate the heat away from the tungsten target

Copper stem

_____ _______ consists of a flow of electrons through a conductor which is known as the _____ ______

Electrical energy, electrical current

The energy that is used to make x-rays

Electricity

X-ray photon passes through atom unchanged and leaves atom unchanged and are also responsible for producing densities and makes dental radiography possible

No interaction

What are the 4 possibilities that can occur when x-ray photons interact with matter?

No interaction, absorption/photoelectric effect, compton scatter, coherent scatter

In photoelectric effect the x-ray photon imparts all of its kinetic energy to the...

Orbital electron, is absorbed, and ceases to exit

At the atomic level absorption occurs as an result of the

Photoelectric effect

In ___________ ___________ an x-ray photon collides with a tightly bound inner shell electron and gives up all of its energy to eject the electron from its orbit

Photoelectric effect

In photoelectric effect what is the ejected electron termed?

Photoelectron

Generators on ________machines produced an x-ray beam with a _______ pattern, whereas ______ constant-potential x-ray machines produce a _________ beam of _________ wavelengths during radiation exposure

older, wavelike pattern, newer, homogeneous,consistent

Two electrical circuits are used in the production of x-rays:

(1) A low voltage, or filament, circuit and (2) A high voltage circuit

The three transformers that are used to adjust the electrical circuits are

1- step-down transformer 2- step-up transformer 3- autotransformer

Kinetic energy of electrons is converted into x-ray photons by 2 ways:

1. General (braking) radiation 2. Characteristic radiation

A step up transformer is used to increase the voltage from the incoming _____ or ______line voltage to the _______ to _______ volts used by the high voltage circuit

110-, 220-, 65,000, 100,000

Constant-potential machines also reduce patient exposure to radiation by __%

20%

The photoelectric effect accounts for ______% of the interactions of mater with a dental x-ray beam

30

Compton scatter accounts for __% of scatter in diagnostic radiography

62

Characteristic radiation requires _____ KvP and higher because the binding of the K shell electron is about ____ KeV

70, 70

Coherent scatter accounts for ____% of the interactions of matter with dental x-ray beams

8

Refers to the total transfer of energy from x-ray photon to the atoms of matter through which x-ray beam passes

Absorption

In production of x-rays both the amperage and the voltage can be

Adjusted

______ ______ describes an electrical current in which the electrons flow in two, opposite directions

Alternating Current (AC)

Sheets of 0.5-mm- thick aluminum placed in the path of the x-ray beam- filter out the nonpenetrating, longer wavelength x-rays

Aluminum discs

The measurement of the # of electrons moving through a conductor

Amperage

Current is measured in

Amperes (A) or milliamperes (mA)

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

Anode/ positive electrode

Serves as a voltage compensator that corrects for minor fluctuations in the current

Autotransformer

Consists of a tungsten wire filament in a cup-shaped holder made of molybdenum

Cathode/ negative electrode

A path of electrical current is a

Circuit

Occurs when a low energy x-ray photon interacts with an outer shell electron

Coherent scatter

As thermionic emission occurs the outer shell electrons of the tungsten atom acquire enough...

Energy to move away from the filament surface and electron cloud forms around the filament

The ________ suspends the x-ray tubehead and houses electrical wires, and also allows for movement and positioning of tubehead

Extension arm

Uses 3 to 5 volts, regulates the flow of electrical current to the filament of the x-ray tube, and is controlled by the milliamperage settings

Filament circuit

Uses 65,000 to 100,000 volts, provides the high voltage required to accelerate electrons and to generate x-rays in the x-ray tube, and is controlled by the kilovoltage settings

High- voltage circuit

The energy and wavelengths vary based on

How electrons interact with tungsten atoms in the anode

What takes place in compton scatter?

Ionization

What takes place in the photoelectric effect?

Ionization

The voltage of the x-ray tube current or the current passing from the cathode to the anode is controlled by the

Kilovoltage peak (kVp)

A lead place with a central hole that fits directly over the opening of the metal housing, where the x-rays exit- restricts size of beam

Lead collimator

Component parts of the x-ray tube are

Leaded glass housing, negative cathode, and positive anode

Leaded glass vacuum tube that prevents x-rays from escaping in all directions

Leaded-glass housing

What are the component parts of the tubehead

Metal housing, insulating oil, tubehead seal, x-ray tube, transformer, aluminum disks, lead collimator, PID

Surrounds the x-ray tube and transformers and is filled with oil-- protects the x-ray tube and grounds the high voltage components

Metal housing/Metal body

In the x-ray tube, the amperage, or number of electrons passing through the cathode filament, can be increased or decreased by the

Milliamperage (mA)

Focuses the electrons into a narrow beam and directs the beam across the tube toward the tungsten target of the anode

Molybdenum cup

Open-ended, lead lined cylinder that extends from the opening of the metal housing of the tubehead- aims and shapes the x-ray beam, sometimes referred to as the cone

Position indicating device (PID)

Coil that receives the alternating electrical current is the

Primary or input coil

Refers to the penetrating beam that is produced at the target of the anode and exits tube head

Primary radiation

The electrical current that energizes the ______ coil induces a current in the _____ coil

Primary, secondary

The conversion from of AC to DC

Rectification

Transformers alter the voltage of the incoming electrical current and then

Route the electrical energy to the x-ray tube

A form of secondary radiation and is the result of an x-ray that has been deflected from its path by the interaction with matter

Scatter radiation

Output coil

Secondary coil

Refers to x-radiation thats created when primary beam interacts with matter

Secondary radiation

The dental x-ray tube acts as a ____-_____ in that it changes AC into DC while producing x-rays

Self rectifier

Characteristic radiation accounts for a very _____ part of x-rays produced in the dental x-ray machine

Small

Used to decrease the voltage from the incoming 110- or 220- line voltage to the 3 to 5 volts used by the filament circuit

Step-down transformer

Has more wire coils than in the primary coil

Step-up transformer

The high-voltage circuit uses both a

Step-up transformer and an autotransformer

What is the purpose of the cathode?

Supply the electrons necessary to generate x-rays

The electrical current is termed direct current (DC) when

The electrons flow in one direction through the conductor

A device that alters the voltage of incoming electricity

Transformer

A device that is used to either increase or decrease the voltage in an electrical circuit

Transformer

The ________ is a tightly sealed, heavy metal housing

Tubehead

Aluminum/leaded-glass covering of the tubehead that permits the exit of x-rays from the tubehead- seals the oil in the tubehead and acts as a filter to the x-ray beam

Tubehead seal

Coiled wire made of tungsten which produces electrons when heated

Tungsten filament

What are the 2 parts of the cathode?

Tungsten filament & the molybdenum

Plate of tungsten, which serves as a focal spot and converts bombarding electrons into x-ray photons

Tungsten target

What are the 2 parts of the anode?

Tungsten target & the copper stem

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

Voltage

Voltage is measured in

Volts (V) or kilovolts (kV)

Heart of the x-ray generating system

X-ray tube

The tubehead contains the ______ that produces x-rays

X-ray tube

Most x-rays are produced in the _______ manner approximately ___% of the x-ray energy produced at anode can be classified as ________ ________

braking, 70, general radiation

In the x-ray tube the _____ produced in the _____ cathode are _______ toward the ______ anode

electrons, negative, accelerated, positive

Absorption depends on the _______ of the beam and the __________ of the absorbing ___________ or _________

energy, composition, matter, tissue

X-ray tube is a _____ vacuum tube from which all the __ has been ____

glass, air, removed

When electron strikes tungsten target their ________ _______ is converted to x-ray _________ and ________

kinetic energy, energy, heat

The rearrangement in characteristic radiation produces a ______ of energy that results in the production of an _________ __________

loss, x-ray photons

The photoelectron has a ________ charge it is readily __________ by other atoms because it has very little ____________ _________ atom that remains has a __________ charge

negative, absorbed, penetrating power, positive

One central area of the leaded-glass tube has a _____ that permits the x-ray beam to exit the tube and directs the x-ray beam toward the aluminum disks, lead collimator, and PID

window