Exam II, ch 2-4, 10. x-ray

what is another name for the exposure switch, that automatically terminates the exposure when the operator's finger ceases to press on the timer button.

"dead-man" switch

What have a negative charge and are constantly in motion orbiting the nucleus?

Electorns

What is the smallest particle of an element that still retains the properties of the element?

Atom

electricity can be defined as electrons in motion. an electric current is a movement of electrons through a conducting medium (such as copper wire).

Both statements are true

Notes for

CH 2-4, 10

do x-rays make the material they pass through radiactive?

No

What is at the center of an atom and revolves around it? And is also made up and formed by the protons and neutrons?

Nucleus

Where is the innermost level and strongest binding energy of an electron orbiting the nucleus found at ?.

On the K Shell

Hydrogen in its simplest form has how many protons?

One

aka: compton scattering. similar to the photoelectric effect, but only a part of the dental x-ray energy is transferred to the electron, and a new, weaker x-ray is formed and scattered in some new direction.

compton effect

what is the unit used to measure radiation exposure

compton scattering

what 3 parts consists on an dental xray unit

control panel, extension arm, tube head

what is the unit used to measure radiation exposure

coulombs per kilogram (roentgen)

what causes more radiation damage to a person, sunlamp or dental and medical radiography?

dental and medical radiography, (most damage to less damage in order: radiography, sunlamp, photography, toaster)

only the shortest wavelengths with extremely high frequency and energy are used to expose?

dental radipgraphs

what flows continuously in one direction

direct current (DC), is well suited for use with digital imaging

what 2 directions can a electric current flow on a wire or conductor

direct current or alternating current

the movement of wavelike energy through space as a combination of electric and magnetic fields.

electromagnetic radiation

an orderly arrangement of all known radiant energies together is called

electromagnetic spectrum

defined as the measurement of ionization in air produced by x- or gamma rays

exposure

what activates the xray production process

exposure button

radiation measurement terminology: (on page 15)

exposure: (SI) coulombs per kilogram - (C/kg), (traditional unit) is roentgen - (R) / absorbed dose: (SI) gray - (Gy), (traditional unit) is rad - (radiation absorbed dose) / dose equivalent: (SI) sievert - (Sv), rem - (roentgen equivalent [in] man)

what is a support from which the tube housing is suspended and allows for moving and positioning the tube head

extension arm

what is an electromagnetic device for changing the current coming into the dental xray machine. they are also, required to decrease ( step down) or increase (step up) the ordinary 110-v or 220-v current that enters the xray machine, step down and step up are located in the tube head.

transformers

all energies of the electromagnetic spectrum share the following properties.

travel at the speed of light, have no electrical charge, have no mass or weight, pass through space as particles and in a wavelike motion, give off an electrical field at right angles to their path of travel and a magnetic field at right angles to the electric field , have energies that are measurable and different.

what is a tightly sealed heavy metal (usually cast aluminum), lead lined housing that contains the dental xray tube, insulating oil, and step up and step sown transformers

tube head (tube housing)

refers to the speed of the wave

velocity

what measures the difference in potential or voltage across the xray tube

voltmeter

the distance between two similar points on two successive waves, and may be measured in the metric system or in angstrom units

wavelength

electromagnetic waves exhibit the properties of

wavelength, frequency, and velocity

examples of electromagnetic spectrum is

x-radiation, cosmic rays, gamma rays, ultraviolet rays, visible light, infrared, television, radar, microwave, radio waves

which of these forms of radiation has the greatest penetrating power ? (visible light, x-ray, sunlamp, radio waves)

x-rays

only a portion of the radiation portrayed on the electromagnetic spectrum are of the ionizing type, what 3 are they

x-rays, gamma, cosmic rays

the audible beeping during exposure of an xray, indicates what

xrays are being generated

what measures the amount of current passing through the wires of the circuit.

milliampere (mA)

how far should you stand away from the xray for protection against radiation.

6 ft

how many impulses are in a second

60 impulses per second: example 1/10th of a second = 6 impulses, 12 impulses = 1/5th of a second. (divide the number into 60 to get your answer)

kVp

60 p. in one minute and one minute to exposure

compton effect accounts for about what percent of the interactions of matter with the dental x-ray beam

60%

characteristic radiation can only be produced when the x-ray machine is operated at or above _____ kilovolts (kVp),

70

characteristic radiation is found

only in the target and is the primary x ray

an all or nothing energy loss.

photoelectric effect

bundles of energy that travel through space at the speed of light are called

photons

x-rays are believed to consist of minute bundles (or quanta) of pure electromagnetic energy called

photons or (bullets of energy)

the line switch on the control panel of the dental xray machine may have 2 types of switches

toggle switch, or keypad

How many basic elements do we currently know of?

118

What are the orbits called around the nucleus?

Electron shells or Energy Levels

What orbits around the nucleus in paths called shells or energy levels?

Electrons

Atoms are composed of 3 basic building blocks, what are they?

Electrons, protons, and neutrons

What is defined as the ability to do work and overcome resistance, (like forms of heat, light, electricity, and x-radiation)?

Energy

What is produced whenever the state of matter ( like water, steam, and ice), are altered by natural or artificial means?

Energy

the wavelengths used in diagnostic dental radiography range from about 0.1 to 0.5 (A) angstrom, and a term meaning radiation with great penetrating power, are classified as

Hard radiation

Atoms that have gained or lost electrons are electrically unstable and are callled? It is defined as a charged particle, also.

Ion

The positively charged atom ion and the negatively charged electron ion are called what when placed together?

Ion Pair

the outer most layer orbiting the carbon atom is?

L

What is define as anything that occupies space and has mass?

Matter

What is the smallest particle of a substance that retains the properties of that substance? and atoms are generally combined with other atoms to form this?

Molecule

What has no charge?

Neutrons

What have a positive charge. the number of protons in the nucleus of an element determines its atomic number?

Protons

which of these electromagnetic radiations has the shortest wavelength? ( radar,, ultraviolet rays, infrared rays, x-rays)

Radar

defined as the emission and movement of energy through space in the form of electromagnetic radiation (x- and gamma rays) or particulate radiation (alpha and beta particles)

Radiation

defined as the process whereby certain unstable elements undergo spontaneous disintegration (decay) in an effort to attain a stable nuclear state.

Radioactivity

dense structures such as bone and enamel appear (white or light gray) on the radiograph called? whereas the less dense pulp chamber, muscles,, and skin appear (dark gray or black) and are called?

Radiopaque: Radiolucent

Atom normally has the same number of protons and electrons in the orbital levels. T or F

True

dental x-rays do not involve the use of radioactivity. T or F

True

frequency is the number of crests of a wavelength passing a given point per second.

True

on a wavelength, the wave moves up and down in a straight line, the crest points at the top of the wave from one point to the other is what they call the Wavelength . (is determined b the distances between the crests.

True

the higher the frequency the more penetrating the radiation. T or F

True

the shorter the wavelength the more penetrating the radiation. T or F

True

unstable isotopes are radioactive and attempt to regain stability through the release of energy, by a process known as decay. T or F

True

the extension arm bracket should be folded into a neutral closed position after used. T or F

True statement

the high speed electron ( called a photoelectron) knocks other electrons form the orbits of other atoms ( forming secondary ion pairs) until all its free electron, and the absorbing material is restored to it original condition.

True statements

on xray machines using a recessed design, the xray tube is located in the back of the tube head, this configuration allows for what type of image

a sharper image

defined as the amount of energy deposited in any form of matter (such as teeth, soft tissues, tx chair), the unit for measuring this is called gray (Gy) or (rad).

absorbed dose

a exposure does not become a dose until the radiation is

absorbed in the tissues

a beam of x-rays passing through matter is weakened and gradually disappears, such a disappearance is referred to as

absorption of x-rays.

wavelength and frequency are inversely related. when the wavelength is long, the frequency is low, resulting in low energy, less penetrating x-rays. when the wave length is short, the frequency is high, resulting in high energy , more penetrating x-rays.

all statements are true

what current changes its direction of flow 60 times per second , and has two phases (positive and negative)

alternating current

what is set by turning a selector knob, depressing the marked push button, or touching a keypad. which determines the available number of free electrons at the cathode filament and therefore the amount of xrays that will be produced.

amperage

x-rays have the following properties

are invisible, travel in straight lines, travel at speed of light, have no mass or weight, have no charge, interact with matter causing ionization, can penetrate opaque tissues and structures, can affect photographic film emulsion (causing a latent image), can affect biological tissue.

the composition of the object or the tissues determines whether the x-rays will penetrate and pass through it or whether they will be absorbed in it. materials that are extremely dense and have a high _____ will absorb more x-rays than thin materials with low atomic numbers.

atomic weight

What is each element made up of?

atoms

defined as ionizing radiation that is always present in our environment

background radiation

how is the tube head attached to the extension arm

by the yoke ( which can revolve 360 degrees horizontally and rotated vertically)

produced when a bombarding electron from the tube filament collides with an orbiting K electron of the tungsten target. the K shell electron is dislodged from the atom. another electron in an outer shell quickly fills the void, and an x-ray is emitted, this is called

characteristic x-rays

unmodifed scattering, also known as Thompson scattering. when a low energy x-ray passes near an atom's outer electron, it may be scattered without loss of energy

coherent scattering

the path the electricity flows is called an electrical circuit. two electrical circuits are used in producing dental xrays what are they

filament circuit - provides low voltage (3-8 V) , to the filament of the xray tube to generate a source of electrons needed for the production of xrays. high voltage circuit - provides the high voltage ( 60-100 kV), necessary to accelerate the electrons from the cathode filament to the anode target.

a measure of the number of waves that pass a given point per unit of time. special unit sign = Hz (hertz) which equals 1 cycle per second

frequency

that is produced when high speed electrons are stopped or slowed down by the tungsten atoms of the dental x-ray tube

general / bremsstrahlung

a high speed electron is slowed down and bent off its course by the positive pull of the nucleus. the kinetic energy lost is converted into an x-ray. the majority of x-rays produced by dental x-ray machines are formed by.

general / bremsstrahlung or (breaking radiation)

short wavelength will have

high frequency, high energy, and more penetrating x-ray.

how long should you wait after exposure before entering the room where the radiation was?

immediately , do not have to wait

where are xrays made

in the anode

inverse square law

increasing or decreasing the distance, closer to the object you (/) by 4, and further away from the object you (x) by 4. also called, doubling the distance.

which of these forms of radiation is least capable of causing ionization of body tissue cells? (cosmic rays, gamma rays, x-rays, infrared light)

infrared light

the basic method of the interaction of x-rays with matter is the formation of

ion pairs

any radiation that produces ions is called

ionizing radiation

what determines the speed of electrons traveling toward the target on the anode and therefore , the penetrating ability of the xrays produced

kilovolt peak (kVp)

what 5 major controls may be operated or will be preset on dental xray machines

line switch to the electrical outlet, milliampere selector, kilovoltage selector, timer, exposure button

a long wavelength will have

low frequency, low energy, and less penetrating x-ray

TO PRODUCE A LARGER QUANTITY OF ELECTRONS AVAILABLE TO PRODUCE XRAYS, INCREASE THE

mA

mA

make the HEAT and needs (5 to 15 mA) 1/100

what are the 4 functions that the metal housing performs

protects the xray tube from accidental damage, increases the safety of the xray machine by grounding its high voltage components to prevent electrical shock, prevents overheating of the xray tube by providing a space filled with oil, gas, or air to absorb the heat created during the production of xrays, lined with lead to absorb any xrays produced that do not contribute to the primary beam that exits through the port in the direction of the position indicating.

what are the timer settings measured in

second or impulses

the systeme internatioonale (SI) unit that has replaced the traditional unit rem is

sievert

the longest of these rays are the Grenz rays, that have only limited penetrating power and are unsuitable for exposing dental radipographs, also called

soft radiation

( low voltage ) decreases the voltage from the wall outlet to approximately 5 V. just enough to heat the filament and form an electron cloud is called

step-down transformer, (located in the cathode)

(high voltage) increases the voltage from the wall outlet to approximately 60 - 100 kVp to propel the electrons toward the target. high voltage current begins to flow through the cathode - anode circuit when the exposure button on the line switch is depressed.

step-up transformer, ( located in the anode)

NOTES FOR CH. 3

the dental x-ray machine: components and functions

the time selected determines the duration of what

the exposure

secondary radiation causes

the film to be fussy or cloudy

Ionization?

the formation of ion pairs

what 2 ways, does the electric current enter the control panel

through a cord plugged into a grounded outlet in the wall , or through a direct connection to a power line in the wall.

what serves to regulate the duration of the interval that the current will pass through the xray tube

timer