Ch 2

Control panel

Contains an on-off switch Indicator light Control devices ---Time, kilovoltage, milliamperage Plugged into an electrical outlet [The portion, usually mounted on the wall, that allows the operator to turn the machine on or off and adjust the exposure time] All x-ray machines have a __, extension arm, and tubehead.

Matter

anything that occupies space and has mass When ___ is altered, energy results.

hydrogen; +1; particles; no

(3) Protons Accelerated __ nuclei Mass of 1 and charge of __ (4) Neutrons Accelerated ___ Mass of 1, __ electrical charge

tubehead; cellular; natural

(The photon comes from the __ of the dental x-ray machine for dental x-rays? A small change at the atomic or molecular level may lead to big changes at the __ level. Other factors that affect the damage that may occur involve the amount of ionization that occurs over an amount of time. Ionization results from __ sources, not just from dental x-rays.

Absorption; photoelectric effect

*Absorption of Energy and Photoelectric Effect* The x-ray photon is completely absorbed within matter or the tissues of the patient. The total transfer of energy from photon to the atoms of matter? An x-ray photon collides with a tightly bound, inner-shell electron and gives up all its energy to eject the electron from its orbit. ---The ejected photoelectron is absorbed by other atoms. [Absorption depends on the energy of the x-ray beam and the composition of the absorbing matter or tissues. The photoelectric effect accounts for 30% of the interactions of the dental x-ray beam with matter.]

ionization; wave; radiation

*Electromagnetic Radiation* All have common characteristics. ---They may be classified as ionizing or non-ionizing. Only high-energy radiations are capable of ___. They are believed to move through space as both a particle and a __; both concepts must be considered. What type of electromagnetic radiation with a useful clinical application has an even shorter wavelength than the x-rays used for dental radiography? (X-rays used for ___ therapy.)

neutral; equal; electron; positive; ion

*Ionization* Normally, most atoms are __. A neutral atom contains an ___ number of protons and electrons. An atom with an incompletely filled outer shell attempts to capture an __ from an adjacent atom. If the atom gains an electron, it has a negative charge. If the atom loses an electron, it has a __ charge. An atom that gains or loses an electron and becomes electrically unbalanced is called an __.

Aluminum disks; lead collimator; PID

*Parts of tubehead* Filter out nonpenetrating, longer wavelength x-rays? Restricts size of x-ray beam? Aims and shapes the x-ray beam? [Tubehead is attached to the extension arm that allows the tubehead to be moved horizontally and vertically to properly position the opening of the collimator in the desired area to be x-rayed]

Tubehead seal; X-ray tube; transformer

*Parts of tubehead* Permits exit of x-rays from tubehead, seals the oil, filters x-ray beam (22) Heart of generating system? (23) Alters voltage of incoming electricity?

Electricity; filament; down; cathode; electrons

*Production of Dental X-Rays* __ from the wall outlet supplies the power to generate x-rays. The current is directed to the __ circuit and step-__ transformer in the tubehead. The filament circuit uses 3 to 5 volts to heat the tungsten filament in the __. Thermionic emission occurs, and the release of __.

velocity; Wavelength; frequency

*Wave Concept* Characterizes electromagnetic radiations as waves The speed of the wave? The distance between the crest of one wave and the crest of the next? [measured in nanometers (one billionth of a meter).] The number of wavelengths that pass a certain point in a given length of time? [The shorter the wavelength, the greater the penetration. Conversely, the longer the wavelength, the less penetrating power.]

Beta; Cathode

1. Electrons *(ex of beta/electron particle=cathode ray)* __ particles are fast-moving electrons emitted from nucleus of radioactive atoms. __ rays are streams of high-speed electrons that originate in an x-ray tube. ---Electrons emitted by a manufactured device

metals; electrons

2. Alpha particles are emitted from the nuclei of heavy __. They exist as two protons and neutrons, without ___.

x-ray tube

A glass vacuum tube (23) --Measures several inches long by 1 inch in diameter Includes: Leaded-glass housing Cathode Anode

Leaded-Glass Housing

A leaded-glass vacuum tube ---Prevents x-rays from escaping in all directions ---One area has a "window" that permits the x-ray beam to exit the tube and directs the beam toward the aluminum disks, lead collimator, and PID.

Circuit; Filament circuit; High-voltage circuit

A path of electrical current? Uses 3 to 5 volts (low-voltage) Regulates flow of electrical current to the filament Controlled by milliampere settings Uses 65,000 to 100,000 volts Provides high voltage required to generate x-rays Controlled by kilovoltage settings

True

A small number of x-rays are able to exit the x-ray tube through the unleaded glass window portion of the tube. X-rays travel through the unleaded glass window, the tubehead seal, and aluminum disks. The size of the x-ray beam is restricted by the lead collimator. The x-ray beam exits the tubehead at the opening of the PID.

Tubehead; high-voltage; overheating

A tightly sealed, heavy metal housing ---Contains the x-ray tube that produces dental x-rays Metal housing Surrounds the x-ray tube and transformers, protects tube and grounds __ components Insulating oil Surrounds x-ray tube and transformers, prevents __ [The part that is lined up with the film holder and directed toward the patient's face]

molecules

Atoms are capable of combining with one another to form ___. two or more atoms joined by chemical bonds, or the smallest amount of a substance that possesses its characteristic properties a tiny invisible particle, as with the atoms

Milliamperage adjustment; Kilovoltage peak adjustment

Can increase or decrease the number of electrons passing through the cathode filament *(Controls quantity)* Can control the current passing from the cathode to the anode *(Controls quality)* [Most dental x-ray units operate at a fixed milliamperage and kilovoltage. The exposure time is the variable most often adjusted according to patient age, size, and density.]

nucleus; electrons; binding

Electrons are maintained in their orbits by electrostatic force between the positive __ and negative __. They are known as the ___ energy of an electron. Electrons are held in their shell by electron-binding energy.

A

Identify the best description of primary radiation: the beam that exits the tubehead the beam that is created when x-rays contact matter the beam that is deflected from its path by matter the beam that is less penetrating

A

Identify the part of the x-ray tube that contains the focal spot: anode cathode filament focusing cup

A

Identify the part of the x-ray tube where x-ray photons are produced: at the positively charged anode at the positively charged cathode at the negatively charged anode at the negatively charged cathode

D

Identify the radiation produced when the primary beam interacts with matter: leakage radiation primary radiation diverging radiation secondary radiation

A

Identify the term used to describe an atom that has lost an electron from its orbit: ion photon neutron particle

A

Identify the term used to describe the x-ray beam that exits the PID: primary radiation secondary radiation scatter radiation direct radiation

D

Identify which of the following element(s) is/are located within the x-ray tube: anode cathode focusing cup all of the above

D

Identify which of the following is false: x-rays cause ionization x-rays cannot be focused to a point x-rays have no charge x-rays travel at the speed of sound

B

Identify which of the following is not a property of x-rays: the ability to penetrate organic matter the ability to fluoresce all materials the ability to produce ionization of matter the ability to produce a latent image

A

Identify which of the following is not a type of electromagnetic radiation: electrons radar waves microwaves x-rays

D

Identify which of the following is not a type of particulate radiation: alpha particles beta particles protons nucleons

D

Identify which of the following processes occurs with ionization: cell death takes place photons penetrate matter radiant energy is converted to heat an electron is displaced from its orbit

No, only the orbiting electrons

Is the nucleus affected by x-rays? The various layers of shells around the nucleus are organized into orbits.

No interaction

no scatter, no ionization

electrons

It is the outer layer of ___ that may be disrupted during dental radiography. Every type of atom has a different number of electrons, giving each atom different overall characteristics.

general radiation

Many electrons that interact with the tungsten atoms undergo not one but many interactions within the target. (long) Most x-rays (about 70%) are produced in this manner. produced when an electron hits the nucleus of a tungsten atom or passes very close to the nucleus of a tungsten atom [The term braking refers to the sudden stopping of high-speed electrons when they hit the tungsten target in the anode. The electron rarely hits the nucleus of the tungsten target, but when it does, all its kinetic energy is converted into a high-energy x-ray photon.]

transfer; sharing

Molecules are formed in two ways: The __ of electrons The __ of electrons between the outermost shells of atoms

Extension Arm

Suspends the x-ray tubehead Houses the electrical wires that extend from the control panel to the tubehead Allows for movement and positioning of the tubehead [The portion connecting the tubehead to the control panel, allowing horizontal and vertical changes in the tubehead]

True

The electrons stay in an electron cloud until the high-voltage circuit is activated. When the exposure button is pushed, the high-voltage circuit is activated. The molybdenum cup in the cathode directs electrons to the tungsten target in to anode. When electrons strike the tungsten target, less than 1% of the energy is converted to x-rays, and the remaining 99% is lost as heat.

Electricity; Electrical current

The energy used to make x-rays? A flow of electrons through a conductor? [Electrical energy consists of a flow of electrons through a conductor.]

Cathode; electrons; filament; molybdenum

The negative electrode? Consists of a tungsten wire filament in a cup-shaped holder made of molybdenum Supplies the ___ necessary to generate x-rays ---The tungsten __ produces electrons when heated. (must have tungsten filament to have xrays) ---The __ cup focuses electrons into a narrow beam and directs the beams toward the tungsten target.

mass; weight; electrons; number

The number of protons and neutrons in the nucleus of an atom determines its ___ number or atomic __. The number of protons inside the nucleus equals the number of __ outside the nucleus and determines the atomic ___. Atoms are arranged in increasing atomic number on the periodic table of the elements.

Primary radiation; secondary radiation; scatter radiation

The penetrating x-ray beam that is produced at the target of the anode? X-radiation created when the primary beam interacts with matter [the soft tissues of the head, the bones of the skull, and the teeth; less penetrating] A form of secondary radiation, the result of an x-ray that has been deflected from its path by an interaction with matter

Anode; plate; copper; photons; heat

The positive electrode? Consists of a wafer-thin tungsten __ embedded in a solid __ rod Converts electrons into x-ray __ ---The tungsten target serves as a focal spot and converts electrons into photons. ---The copper stem functions to dissipate __ away from the tungsten target. [The purpose of the copper stem with air or oil immersion is to absorb the heat energy. Electrons travel from the cathode to the anode. Most of the x-rays (99%) are absorbed and given off as heat. The remaining 1% leaves the tubehead and is directed toward the patient.]

Ionization; pair; atom; electron

The production of ions, or the process of converting an atom into ions? When an electron is removed from an atom in the ionization process, an ion ___ results. ---The __ becomes the positive ion. ---The ejected __ becomes the negative ion.

Compton Scatter

The x-ray photon is deflected from its path during its passage through matter. -In Compton scatter, ionization takes place. --An x-ray photon collides with a loosely bound, outer-shell electron and gives up part of its energy to eject the electron from its orbit. The x-ray photon loses energy and continues in a different direction at a lower energy level. The ejected electron is termed a Compton electron. [At the atomic level, the Compton effect accounts for most of the scatter radiation. Compton scatter accounts for 62% of the scatter that occurs in diagnostic radiography.]

No interaction

The x-ray photon passes through the atom unchanged and leaves the atom unchanged. These photons are responsible for producing densities on film and make dental radiography possible. [It is possible for an x-ray photo to pass through matter or the tissues of a patient without any interaction.]

Step-Down Transformer; primary

Used to decrease voltage from the incoming 110- or 220-line voltage to the 3 to 5 volts used by the filament circuit More wire coils in the __ coil than in the secondary coil [The current travels through the step-down transformer to the filament of the cathode.]

Step-Up Transformer; secondary

Used to increase incoming voltage to 65,000 to 100,000 volts used by the high-voltage circuit More wire coils in the __ coil than in the primary coil

Direct current; Alternating current; Rectification

When electrons flow in one direction through a conductor? (DC) When electrons flow in two opposite directions? (AC) The conversion of alternating current to direct current? [The dental x-ray tube acts as a self-rectifier in that it changes AC to DC while producing x-rays. This ensures that the current is always flowing in the same direction, more specifically, from the cathode to the anode.]

C

Which of the following is true concerning atomic structure? Both protons and electrons carry positive electrical charges An electron does not have any mass The strongest binding energy for electrons is found closest to the nucleus The A shell is located closest to the nucleus and has the weakest binding energy

B

Which of the following is true of the conversion of the kinetic energy of the electrons into x-ray photons through general radiation? Most x-rays are produced in this manner; approximately 99% of the x-ray energy produced at the anode can be classified as general radiation General radiation consists of x-rays of many different energies and wavelengths. General radiation is produced when a high-speed electron dislodges an inner-shell electron from the tungsten atom. General radiation occurs only at 70 kVp and above.

True

X-rays differ in energy and wavelength. Two mechanisms General (braking) radiation Characteristic radiation

Autotransformer

a voltage compensator that corrects for minor fluctuations in the current

Coherent Scatter

an x-ray photon that has its path altered by matter. A low-energy x-ray photon interacts with an outer-shell electron. No change in the atom occurs, and an x-ray photon of scatter radiation is produced. [aka unmodified scatter The x-ray photon simply changes direction without a change in energy, thus going "unmodified." Coherent scatter accounts for 8% of the interactions of the dental x-ray beam with matter]

Electrons; 1/1800; orbits; highest

are tiny, negatively charged particles These have very little mass, approximately ___ as much as a proton or neutron. Electrons travel around the nucleus in well-defined paths known as __ or shells. The shell located closest to the nucleus has the __ energy level.

Ionizing Radiation; Particulate radiation and Electromagnetic radiation

capable of producing ions by removing or adding an electron to an atom? 2 groups?

Particle concept; no; straight

characterizes electromagnetic radiation in terms of discrete bundles of energy called photons or quanta. ---Photons are bundles of energy with __ mass or weight. ---Photons travel as waves at the speed of light and move through space in a __ line. A photon is a tiny bundle of pure energy that has no weight or mass and has the ability to collide with electrons found in the outer orbital shells of otherwise electrically stable atoms, resulting in ionization when an electron is lost.

Binding energy; K; volts

determined by the distance between the nucleus and the orbiting electron? The strongest binding energy is found closest to the nucleus in the __ shell. It is measured in electron ___ or kilo electron volts.

transformer; step-down transformer, Step-up transformer, and Autotransformer

device used to either increase or decrease the voltage in an electrical circuit Three types?

x-radiation; X-rays; photons

high-energy, ionizing electromagnetic radiation? weightless bundles of energy without an electrical charge that travel in waves with a specific frequency at the speed of light? X-ray __ interact with the materials they penetrate and cause ionization (bone, cheek, gingival tissue).

atom

is a central nucleus and orbiting electrons The identity is determined by the composition of the nucleus and the arrangement of orbiting electrons. Nuclear binding energy holds nucleus together

Nucleus; empty

is composed of protons and neutrons Protons have positive electrical charges. Neutrons carry no electrical charge. Most of the atom is __ space.

absorption of energy and photoelectric effect

no scatter, ionization

Characteristic Radiation

produced when a *high-speed* electron dislodges an inner-shell electron from a tungsten atom and causes ionization of that atom (short) The remaining orbiting electrons are rearranged to fill the vacancy. *This occurs only at 70 kVp and above.* [This arrangement produces a loss of energy that results in the production of an x-ray photon. Characteristic radiation accounts for a very small part of x-rays produced in the dental x-ray machine.]

Electromagnetic Radiation

propagation of wavelike energy (without mass) through space or matter. ---Oscillating electric and magnetic fields are positioned at right angles to one another. They may be artificial(xray machine, microwave) or occur naturally (sun). They are arranged in the electromagnetic spectrum according to their energies. (made up of photons that travel through space at the speed of light in a straight line with a wavelike motion.)

Compton scatter

scatter, ionization

Coherent scatter

scatter, no ionization

radiation

the emission and propagation of energy through space or a substance in the form of waves or particles used in dentistry

atoms

the fundamental unit of matter All matter is composed of ___. It takes many molecules of matter, grouped together, to be able to see them as a group with the naked eye.

Amperage; Voltage

the measurement of the number of electrons moving through a conductor? ---Current is measured in amperes (A) or milliamperes (mA). the measurement of electrical force that causes electrons to move from a negative pole to a positive one. ---Measured in volts (V) or kilovolts (kV). [Both of these can be adjusted]

radioactivity

the process by which certain unstable atoms or elements undergo spontaneous disintegration, or decay, in an effort to attain a more balanced nuclear state

Particulate radiation; electrons, alpha particles, protons, and neutrons

tiny particles of matter that possess mass and travel in straight lines and at high speeds? 4 types?