DHYG 113 Test 3: Key Terms & Definitions in Dental Radiography

The fundamental unit of matter is the...

atom

The nucleus of an atom contains

protons and neutrons

Which subatomic particle carries a negative electrical charge?

electron

Which of the following statements is true of ionization?

a. An atom that gains an electron has a negative charge, and an atom that loses an electron has a positive charge.

b. An atom that loses an electron will have a positive charge.

c. An atom that gains an electron will have a negative charge.

d. An atom that loses an electron will have a negative charge.

A.

gain= negative

lose= positive

t or f?(1) Radiation is the emission and propagation of energy through space or a substance in the form of waves or particles. (2) Radioactivity can be defined as the process by which certain unstable atoms or elements undergo spontaneous disintegration, or decay, in an effort to attain a more balanced nuclear state.

both true

(radiation= propagation of wave)

(radioactivity= spontaneous disintegration)

Which of the following statements is true of wavelength in reference to radiation?

a. Milliamperage controls the wavelength and energy of the x-ray beam.

b. X-rays with longer wavelength are less likely to be absorbed by matter.

c. X-rays with longer wavelength have less penetrating power.

d. X-rays with shorter wavelength have less penetrating power.

C

- milliamperage controls number of electrons passing through cathode filament

- KILOVOLT controls wavelength and energy of beam

- longer wavelengths are MORE likely to be absorbed and have less penetrating power

- shorter wavelengths have MORE penetrating power

______________ is a measurement of force that refers to the potential difference between two electrical charges.

voltage

______ is the interval of time during which xrays are produced.

exposure time

________ distance between the crest of one wave and the crest of the next wave

wavelength

__________ is the unit of measure to describe the number of electrons, or current flowing through the cathode filament

ampere

When the kilovoltage is increased...

a. photons move from the cathode to the anode with more speed.

b. electrons move from the cathode to the anode with more speed.

c. photons move from the anode to the cathode with more speed.

d. electrons move from the anode to the cathode with more speed.

B

- photons are only produced in anode

- always cathode--> anode

The kV represents...

the maximum or peak voltage of an alternating current

When lower kilovoltage settings are used, an image with ____ will result.

high contrast

low kVp= HIGH contrast

exposure time is measured in...

hundredths of a second.

the quantity of xrays produced is controlled by ...

milliamperage (amp= amount)

According to the inverse square law, the intensity of radiation is __________ proportional to the ______________ from the source of radiation.

inversely; square of the distance

Radiolucent refers to that portion of a dental image that is

black

If the operating kilovoltage is increased, the receptor density ____ because the average energy of the x-rays is raised.

increase

increase kVp= increase density

which electrons have the greatest binding energy?

K shell

what type of electrical charge does the electron carry?

negative

what term describes two or more atoms that are joined by chemical bonds?

molecule

which statement describes ionization?

a. atom without a nucleus

b. atom that loses an electron

c. atom with equal number of protons and electrons

d. none of the above

B

- ionization deals only with electrons

what term describes the process by which unstable atoms undergo spontaneous disintegration in an effort to attain a more balanced nuclear state?

radioactivity

which is not a type of particulate radiation?

a. alpha

b. beta

c. protons

d. nucelons

D it is suppose to be neutrons not nucleons

- particulate : (PANE)

1. proton

2. alpha

3. neutron

4. electron

- beta

- cathode ray

which is not a type of electromagnetic radiation?

a. electron

b. radar waves

c. microwaves

d. x-rays

A.

- electron is part of particulate radiation

-electromagnetic examples include cosmic rays, gamma rays, x-rays, ultraviolet rays, visible light, infrared light radar waves, microwaves, and radio waves

which statement is incorrect?

a. velocity is the speed of wave

b. wavelength is the distance between waves

c. frequency is the number of wavelengths that pass a given point in a certain amount of time.

d. frequency and wavelength are inversely related

B. should be distance between CREST of the waves

which statement is incorrect?

a. x-ray travel at speed of sound

b. x-rays have no charge

c. x-rays cannot be focused to a point

d. x-rays cause ionization

A. should be speed of light

x-rays are _______________ invisible/ visible

invisible

x-rays have_______________ no mass/ mass

no mass

x-rays have _______________ no charge/charge

no charge

x-rays travel at _______________ speed of light/speed of sound

speed of light

x-rays travel in _______________ straight/no straight lines that can be deflected or scattered

straight

x-rays ______________ can be focused to a point and do not diverge from a point/ cannot be focused to a point and diverge from a point

cannot be focused to a point and diverge from a point

x-rays can/cannot penetrate liquids, solids and gases

can

xrays are absorbed by ...

matter

do xrays cause ionization?

yes

do x-rays have fluorescence capability?

yes, can cause certain substances to fluoresce or emit radiation in lover wavelengths (UV light)

which statement is correct?

a. x-rays are a form of electromagnetic radiation; visible light is not

b. x-rays have more energy than does visible light

c. x-rays have a longer wavelength than does visible light

d. x-rays travel more slowly than does visible light

which regulates the flow of electrical current to the filament of the x-ray tube?

a. high-voltage circuit

b. low- voltage circuit

c. high-voltage transformer

d. low- voltage transformer

B. low voltage circuit AKA filament circuit

which is used to increase voltage in high-voltage circuit?

a. step-up transformer

b. step-down transformer

c. autotransformer

d. step- up circuit

step up transformer

which does not occur when the high-voltage circuit is activated?

a. the unit produces an audible and visible signal

b. electrons produced at the cathode are accelerated across the tube to the anode

c. x-rays travel from filament to the target

d. heat is produced

C. it is supposed to be ELECTRONS NOT XRAYS

what is the location where x-rays are produced?

positive anode

what is the location where thermionic emission occurs?

negative cathode

(this is release of electrons from tungsten filament when electrical current passes through it and heats filament)

what accounts for 70% of all x-ray energy produced at the anode?

general or braking radiation

(characteristic radiation occurs only at or above 70 kVp)

which occurs only at 70kVp or higher and accounts for a very small part of xrays produced in dental xray machine?

characteristic radiation

which describes primary radiation?

a. radiation that exits the tubehead

b. radiation that is created when xrays come in contact with matter

c. radiation that has been deflected from its path by interaction with matter

d. none of the above

A

(B is secondary, C is scatter)

what is scatter radiation?

radiation that has been deflected from its path by interaction with matter

which type of scatter occurs most often with dental x-rays?

COMPTON

(coherent is only 8%)

in dental imaging, the quality of the x-ray beam is controlled by

kilovoltage

(quantity is miliamperage)

what is the current kilovolt range

70 to 100 kV

a higher kilovoltage produces xrays with:

1. greater energy levels

2. shorter wavelengths

3. more penetrating ability

identify the unit of measurement used to describe the amount of electric current flowing through the xray tube:

ampere

radiation produced with high kilovoltage results in ....

short wavelengths

in dental imaging, the quantity of radiation produced is controlled by

milliamperage and exposure time

increasing milliamperage results in an increase in...

1. temperature of filament

2. number of xrays produced

( regulates temp of cathode filament)

milliamperage range is

6 to 8

the overall blackness or darkness of an image is termed

density

if kilovoltage is decreased with no other variations in exposure factors, the resultant image will appear....

lighter

* if kvp decreases, then density decreases and contrast increases***

( decreased kVp= lighter image (density)= higher contrast)

(increase kVp= darker image (density) = low contrast)

identify the term that describes how dark and light areas are differentiated on an image

contrast

an image that has many light and dark areas with FEW shades of gray is said to have....

high contrast

*many black,white areas and FEW shade gray= high contrast***

** many shades of gray= low contrast **

an image with few shades of gray was produced with...

low kVp

low kVp= high contrast= few shades of gray

high kVp= low contrast= many shades of gray

Increasing milliamperage alone results in an image with:

increased density

the total energy contained in the xray beam in a specific area at a given time is termed:

intensity

increasing which of these four controls will increase the intensity of the xray beam?

1. exposure time

2. kilovoltage

3. milliamperage

4. source-to-receptor distance

1, 2, 3

the greater the distance of source-receptor= less intensity of xray beam

if the target receptor distance is doubled, the resultant beam will be...

one fourth as intense

if the target receptor distance is tripled, the resultant beam will be ...

one ninth as intense

the half-value layer is the..

aluminum needed to reduce the x-ray beam intensity by half

if the half value layer is 3mm, what thickness of aluminum is necessary to decrease the intensity by half?

3 mm

an increase in milliamperage will cause a _______ in density and that image will appear________

increase; darker

increasing operating kilovoltage will cause an ________ in density and the image will appear _______

increase; darker

increasing exposure time will cause an _______ in density and the image will appear _______

increase; darker

a dental patient has thick soft tissues and dense bones. to compensate for this increase in subject thickness and to provide an image of diagnostic density, the dental radiographer may....

1. increase exposure time

2. increase milliamperage

or

3. increase kilovoltage

the difference in degrees of densities between adjacent areas on a dental image is termed:

contrast

a dental image that demonstrates many shades of gray is ...

low contrast ; or long scale contrast

a dental image that demonstrates very dark areas and very light areas is said to have..

high contrast ; or short scale contrast

the one exposure factor that has a direct influence on the contrast of dental image is

kilovoltage

the type of contrast preferred in dental imaging is....

a compromise between short-scale contrast and long-scale contrast

_______ scale contrast shows radiolucent caries to stand out

short

________ scale contrast allows to see subtle change in bone loss associated with periodontal disease

long

the stepwedge is used for all of the following except:

a. to demonstrate short scale and long scale contrast

b. to monitor quality control of film processing

c. to increase penetrating quality of xray beam

d. to demonstrate densities

C (this is for kVp)

the capability of the receptor to reproduce distinct outlines of an object is termed...

sharpness

the unsharp or blurred edges seen on an image are termed

penumbra

the geometric characteristic that refers to an image that appears larger than its actual size is termed....

magnification

a variation in the true size and shape of the object being imaged is termed.

distortion

decrease focal spot= _________ sharpness

increase

increase crystal size = ______ sharpness

decrease

decrease crystal size= ________ sharpness

increase

decrease movement = ________ sharpness

increase

increase target-receptor distance= _______ magnification

decrease

increase object receptor distance = ______ magnification

increase

(distance between tooth and receptor. therefore, a decrease distance between the two results in decreased magnification)

object and receptor are parallel= _______ distortion

decrease

beam perpendicular to object and receptor= _______ distortion

decrease

beam not perpendicular to object and receptor= _______ distortion

increase

the portion of the dental image that appears black or dark is

radiolucent

the portion of a dental image that appears light or white is termed

radiopaque

what appears most radiolucent on an image

air space

what appears most radiopaque on a dental image

1. bone

2. enamel

3. dentin

the overall blackness or darkness of a dental image is termed

density

A photographic image produced on a receptor by the passage of x-rays through teeth and related structures

dental radiograph

A beam of energy that has the power to penetrate substances and record image shadows on photographic film

Xray