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212 Cards in this Set

  • Front
  • Back
Who discovered X radiation?
Wilhelm Conrad Roentgen

Director of Physics

Nov 8, 1895
What did Welhelm Conrad Roentgen discover?
1859-95 he experimented with partially evacuated glass tubes (Crooks Tube)

e- flowed from anode to cathode with hi voltage
What did Roentgen observe at the end of the Crooks tube?
illumination bc it was coated with Fl
Instantaneous emission of light.
Substance that causes fouorescence

Barium, platinocyanide
emits green, yellow light
What caused Fluorescence?
Due to unknown ray that penetrated glass and paper

Unknown rays were called X rays
When did roentgen perform first x ray?
Dec 1895
of bertha's hand
exposure time of 15 min
Who won first nobel physics prize?
in 1901. Roentgen
When did Roentgen die?
1923 at 78 yrs old
Who first made dental radiograph?
Dr. Otto Walkhoff did first dental xray of patients jaw usuing photographic emulsion wrapped in paper with rubber dam. exposure time of 25 min.
First dental radiograph in US
William Rollins DDS
Edmund Kells
1896 New Orleans
Developed film holder to hold glass plate

Exposure time 15 min
first to pay price for poor radiation hygience
Edmund kells

hands were exposed to tube chronically when setting the tube so he got ulcers
In early days, what influenced the the quality and quantity of Xrays?
How did edmund kells die?
Howard Raper

Introduced Dental Radiology Book

Invented Bitewing film 1926
When were bitewings developedD?D
1926 by Howard Raper
Will David Collidge
Born in Mass.
Worked and studied at MIT
developed a new evacutated xray tube which allowed xrays to have a consistant exposure time and quality

Also his work with Tungston filament played a big role in development of modern xray
Where is current applied fro xray?
to cathode to make free electrons. xrays are made when the reapidly moving e- are suddenly stopped as they strike metal target of tube
Uses of Xrays
med-diagnosis and treatment
industrial users
How do xrays make image?
xrays are transmitted through the object, they ineteract with the xray film emulsion and make an invisible image
objective of dental xray
obtain accurate info to aid in diagnosis
intraoral radiography
film inside patients mouth and xray source is outside
extraoral radiography
film and xray sourc outside the patinets mouth
Number of intraoral film sizes
Size 3 film
used for bitewings
Sze 4 film
used for occlusal radiography to look at the whole arch
Size 1 film
placed vertically used to take pic of anterior periapical (PA) xray
Size 2 film
placed horizontally used to take posterior periapical (PA) xray
periapical film
show the entire tooth and its surrounding structures

establishes: root/crown ration, root morph, and to evaluate the status of the periapical bone.
What do periapical films show?
the entire tooth and its surrounding structures
shows crowns and necks of teeth and supporing marginal alveolar crestal bone of both arches simultaneously
Purpose of Bitewing
1. detect decay on proximal surfaces of coronal and cervial regions of teeth
2. to examine the interproximal crestal bone
Occlusal radiograph
shows large area of either maxilla or mandible

useful for fractrue, path, root fragments, and unerupted teeth
Advantage and disadvantage of extraoral radiograph
advantage- broad anatomical coverage

Disadvantage- lack of fine anatomical detail
sagital plan
divides r and l
coronal plane
divides front from back
Axial plane
diviedes top from bottom

Example" amalgum stops radiation completely so it is radioopaque. so is bone
Dark/ black
More density
Soft tissue in root canal
physical manifestition
occupies space and has inertia. has mass. can be a solid, liquid or gas
2 divisons of matter
elements and compounds
smallest part of an element
smallest part of an element. cant be subdivided by ordinary chem means
can only be broken into subatomical particles by hi energy
protons and neutrons within the nucleus of an atom
transmission of enery through space and matter. Xrays penetrate tissue
Atomic number Z
number of protons in nucleus or number of e- in nuetral atom
mass number
number of nucleons, protons plus neutrons
How are electrons held in place?
by electrostatic forces of positively charged nucleus
Electron binding energy
energy required to remove an e- from its orbit.


energy that must be supplied to pull e- away from atom
what happens as e- jump from lower energy to higher energy shelll?
release e-
inner shell e-
closely bound to nucleus bc more forces are acting on them so higher energy. binding evergy is much higher in the inner shell
What causes binding enery to remove e-?
x ray
when a neutral atom acquires a charge
what is required to overcome the electrostatic forces that bind the electrons to the nucleus
what is a form of energy that forms a ion pair
two types of radiation
particulate radiation
atomic nuclei or sub atomic particles moving at hi velocity.

Example: alpha and Beta particles, cathode rays
Alpha particles
type of particulate radiation
composed of 2 protons and 2neutrons so + charge. emitted from nuclei of heavy metals. Densely ionized matter with lo penetration. gives off large energy within a short distance
are alpha particles bad?
yeah because they give off energy densely and quickly in one area so destroys cells
Beta particles
neg charge
Emerge from nucleus of radioactive atom. more penetrating that alpha and less densely ionizing.
Cathode rays
neg chare
originate from xray tube
more penetrating than alpha particle and less densely ionizing
Linear Energy Transfer LET
rate of loss of enery from the particle as it moves throught the matter
LET of alpha particle
hi bc all energy is given off in a small area
LET of beta particle
lo LET bc gives off energy more slowly over a larger area than alpha
Electromagnetic radiation
proopagation of energy through space accompanied by electric and magnetic fields
when is electromagnetic radiaion generated?
when velocity of an electrically charged particle is changed
Examples of electromagnetic radiation
radio waves
light waves
gamma rays
where do gamma rays originate from?
atomic nucleus
Where do x rays originate from?
orbiting electrons
two theories of interactions of electromagnetic radiation
1. particle concept
2. wave concept
2 types of x radiation
ionizing and electroradiation
Particle concept of electromagnetic radiation
particles are discreate bundles of energy with NO mas and travel and speed of light carring a specific amount of energy
Wave concept of electromagnetic radiation
propagation of wave enery through space at speed of light. electric and magnetic fields move forward like ripples. exhibits properites of wavelength and frequency
distance between crests of two waves
Wavelenght frequency correlation
when waveleght long, lo frequency, less penetration

when wavelenght is short, hi frequency, more penetration
number of waves passing through a point per second
What characterized hi energy photons?
What characterizes lowere energy photons like radio waves
When are electromagnetic radiations considered to be ionizing?
if they have a photon energy in excess of 124 eV which is a wavelength of 10-6 cm
Properties of Xrays
cant see hear or smell
penetrates matter
no mass and no charge
travel in straight line
diverge from source
can be straight line
heterogenous energy
ionize gas
make chem and bio changes in tissue
Can xrays be focused on a point?
no just an area
how are xrays absorbed?
differentially absorbed. all shades of gray, white, blck based on diff tissues with diff densities
is fat radiolucent or opaque?
periodontal lig radiolucent or opaque?
Describe Xray beam?
heterogeneous and has certain quality and quantity
What influences beam intensity?
exposure time
currenct mA
beam energy kVp
Source film distance
What is effected by bean intensity?
number of xray photons produced

Energy of xray photons
mean energy of bean
max energy of beam
What happens as exposure time increases but mA and kVp are held constant?
no of photons increase
mean photon nrg is unchanged
max phonton nrg is unchanged
How many impulses in one sec?
What happens as mA increases?
No of photons increase
mean nrg unchanged
max nrg unchanged

Same results as increasing exposure time
What happens as tube voltage kVp increases
increases max nrg of photons
increases mean nrg of photons
increases no. of photons made
what does mA control?
what does kVp control/
half value layer
thickness of absorbing materials (al)required to reduce the intensity of the beam to one half its original value
what happens to HVL as average energy of xray beam increases?
Large HVL
Hard radiation more penetration through tissues
small HVL
Solt radiation
Less penetration through tissue
Radiation is easily absorbed
If kVp increases from 50 to 100 how much will xray intensity increasee?
by 4
what does increased intensity result in on the film?
reducing intesity of beam by selectively removing the longer wavelength less penetrating photons by using Al filters
What happens as filtration increases?
no of photons decrease
mean energy increases
max nry is unchanged
types of filtration
1. inherent filtration
2. added filtration
3. total filtration add 1 & 2
Inherent filtrating
photons are absorbed by:

glass wall of xray tube
insulating oil
Barrier material to prevent oil leakage
Added filtration
used bc inherent filtration is not enough to meet standards recomended by NCRP

Thin sheets of AL are added over the xray machine
With NCRP how much Al equivalent of total filtration should there be with less that 50 kVp?
50-70 kVp? over 70 kV[?
50 kVp 0.5 mm AL
50-70 kVp 1.5 mm Al
70 kVp 2.5 mm Al
restricts the size and shape of xray beam

it is a metallic barrier made of lead

Reduces pt exposure bc increases mean nrg and improves image quality of reducig fog
Types of collimation
1. round
2. rectangular
What type of collimation is recommended?
As collimation restricts the size and shape of the beam (collimation decreases) what happens?
No. photons decreases
Mean nrg unchanged
max nrg unchanged
inverse square law
relationship between distance and beam intensity
what is intensity of beam at a given point inversely poroportional to?
square of the distance from the focal spot
what does increased film source distance do to beam intensity?
reduces it
What happens as distance of source film increases?
no of photons decrease bc they are more spread out

mean nrg unchanged
max nrg unchanged
The greater the source film distance, the ______ the beam intensity
What must increase with increased distance?
exposure time
what decreases with increased source film distance
decreased beam intensity and less radiation
What things decrease radiation dose?
less beam intensity
greater source film distance
increased source film distanc
If distance is reduced to one half, beam intensity increases by how much?
4 times
if distance is reduced 3 times, how much does beam intensity increase?
9 times
if distance of source is doubled what happens to beam intensity ?
decreases by four
if a person standing 3 feet from an xray source receives 4 Rads of exposure how much would they receive at 6feet?
1 Rad
what does an increase of 15 kVp require?
half of exposure time
what does the decrease of 15 kVp need?
double exposure time
A film is exposed at 10 mA for 12 sec. How much exposure time in sec. is required is mA is changed to 12?
mA (old)+mA (new)

10 mA X 12 sec = 12 mA
so sec=10
as xrays pass through the matter there is a gradual loss of energy and xrays graddually disappear
gradual reduction in the intensity of xray beam is called what?
How does attenuation occur?
1. photelectric absorbtion
2. comptom scatter
What percent of photons pass through patients without interaction?
9%. this causes darker density or radiolucent areas on the radiograph after the film has been processed
photoelectric absorption
30% of photons are absorbed this way on dental xray

Does not interact with film
So clear or white ares are seen-radioopaque
describe steps of photoelectric absorption
1. xray photons is absorbed
2. incident photon with a little more energy than the binding energy of a K shell e- ejects e- from orbit. its is called photoelectron flies in space and is absorbed by another atom
3.ionization occurs
4.L shell jusmps to K shell and gives off Characteristic radiation
What does xray absorption depend on?
photon nrg kVp
Structure thickness
density of obj
atomic no of obj
describe photon nrg
higher kVp->hi energy photons->greater penetration less absorbtion
what happens to absorbtion if you increase Z
increase absorbance thats why lead is used for the collimater
Xrays are deflected in all directions and contribute to unusful info to film
What does scatter cause?
Types of Scatter?
1.Coherent scatter
2.compton scatter
coherent scatter
lo nrg incident photon passes near outer shell e-. no loss of energy. direction of the incident xray photon is altered
Compton scattering
most common interaction between xray and body tissues

responsible for almost all scatter radiation
moderate energy xrays strike outer shell e- or loosely bound e- causing it to eject from its orbit
compton scatter
what does compton scatter depend on?
angle of defelection
if photons have a narrower angle of deflection, what happen?
energy is retained and there is a bigger chance of reaching the film and producing fog
e- density
greater the no. of e-, higher the probabitiy of compton scatter.
Where is compton scatter greatest?
in bone bc hi Z
how can compton scatter be minimized?
rectangular collimation
shorter exposure time
faster film
how are xrays produced?
when hi speed e- decelerate or stop

Kinitic nrg becomes electromagnetic radiation
Conditions necessary for xray production
1. gereration of e- by filamen
2. focus e-
3. produce hi speed e-
4. stop hi speed e- @ target
source of e-
cathode (tungston coil)
e- made by heating cathode
Thermionic emission
boiling of e- from filament by absorption of heat
what does temp of filmant control?
quantity of e- made
how can temp be increased?
increase mA or exposure time
What does increaseing kVp do?
cathode becomes more neg and anode becomes more pos. results in flow of hi speed e- toward the anode
what happens to e- flow as potential difference increases/
spped of e- increase
when cathode e- stream strikes the anode target, 2 xrays occur. what are they?
1. general "bremsstrahlung radiation
2. characteristic radiation
Bremsstrahlung radiation

bulk of dental xray

cathode e- is deflected and deceleratted or stopped by nucleus of tungsten and kinitic nrg is lost as xray
two mechanisms of bremsstrahlung radiation
1. direct hit of e- to nucleus
2. e- defelcted and decelerated by interaction with nucleus
What type of energy does bremsstrahlung radiation have?
heterogenous. energy and wavelength are not uniform
what does energy of emitted xray photon resulting from deceleration of e- depend on?
how close the e- pass to the nucleus

energy of e- (eV)

Charge of nucleus
characeteristic radiation
makes small porttion of xray

produces xray photon w/ energies specific for the target material

results in homogenours wavelength and energy
process of characteristic radiaion
incoming e- interact w/inner orbital e- of target atom

incident e- and k shell e- leave the target atom

Removal of an e- fro te target atom causes the atom to have an excess positive charge of energy

target atom becomes ionized
how to get rid of excess charge in characteristic radiaiton
e- drops from outer shell to inner shell causing release of nrg as xray. nrg is characteristic of target material and involved in orbital
energy emitted by the shift of e- from one shell to another is equal to what in characteristic radiation?
differnces in energy between two orbitals
What happens when DC is applied to an xray generator?
kilovoltage increaces
what do all cathodes have same of/
same energy and results in homogenous radiation in characteristic radiation
advantage of using DC in xray machines
xray photons with similiar energies lower no. of non diagnostic xrays allowing less radaion dose to pt
why do we need to measure xrays?
ionizing radaion harmful
know potentioal harmful effects
device for measuring doses xradiation
output of xray machine and radiation reaching living tissue
absorbed dose
radiation absorbed by living tissue
equivalent dose
comparison of biological effects produced by different ionizing radiations
Unit of exposure
R is defined as quantity of photons that make a defined no. of ion pairs in a cbic cm of air

SI unit is C/kg
absorbed dose
measure of the energy absorbed by any type of ionizing radiation per unit massof any type of matter

SI is Gray

Absobed dose is typically used when indication harful effects
What is usedto compare bio effects of diff types of radiation on tissues
equivalent dose
personnel monitoring devices
film badges

optically stimulates luminescene tech
are of eruption of mandibular 1st premolar
10-12 yers
height of contour of mandibular 1st premolar
facial-cervical third 1/2 mm

lingula-middle third 1 mm
what is facial surface of mandibular first premolare similiar to?
predominant cusp on mandibular first premolar
facial. it occludes
describe facial cusp tip of mandibular first premolar
cusp tip more rounded on premolar and is displaced medially
most promininat ridge on mandibular first premolar
central facial ridge
proximal contacts of mandibular first premolar
slightly cervical to junction of middle and occlusal thirds
shape of mandibular first premolar
shape of mandibular first premolar occulual table
how do mesial marginal ridges and distal marginal ridgles run on mandibular first premolar?
mesial ridge runs parralel to canine and distal amanginal rige run horizontal to canine
no. of pits on mandibular first premolar
2 in central groove
what is visible from looking at lingual side of mandibular first premolar?
mesial and distal sufaces and large portion of occlusal surface is visible
how is occlusal table placed on mandibular first premolar?
occlusal tbale is tipped lingually
difference in lingula and facial cusp of mandibular first premolar
lingula cusp is shorter that facial
describe mesial marginal ridge of mandibular first premolar
mesial marginal ridge more nearly parallels the slope of the linulal ridge of the facial cusp
difference in sides of mandibluar first premolara
more curvature of cervial line on mesial than distal
What seperates mesial lobe from lingual cusp on mandibular first premolar
mesiolingual groove
number of occlusal fossa on mandibular first premolar
two occlusal fossa
difference in mesial and distal proximal contacts on mandibular first premolar
mesial side is flat and much narrower while distal is has a wide proximal contact
only tooth with mesiolingual developmental groove
first mandibular premolar
does lingual cusp of mandibular first premolar occlude with max teeth?
no only the facial cusp does
age of eruption of mandibular second premolar
10-12 years
height of contour of mandibular second premolar
facial in cervial third 1/2mm

lingual-middle third 1 mm
what erupts first, first or second premolar?
difference in facial cusps tip between first and second mandibular premolars
second facail cusp tiip is more rounded
facial cusp of mandibular second premolar
cusp tip reounded and displaced mesially
proximal contacts of mandibular second premolars
proximal contact in middle thrid
shape of mandibuar second premolar rroot
baenet shaped
lingual view of mandibular second premolar
no facail side visible and not much occlusal side visible
what sepererates lingula cusp of mandibular second premolar?
developmental groove
larges lingual cusp on mandibular second premolar
difference in mandibular first and second premolar proximal view
on the first the occlusal suface slopes

onthe second the occlusal surface has two cusps like a V
describe mesial and distal marginal ridges of mandibular second premolar
mesial and distal marginal ridges more perpendicular to long axis of tooth. distal marginal ridge is at a lowere level occlusocervically
three forms of second mandibular premolar

based on occlusal surface
# of cusps of second mandibular premolar
2 or 3
Y sencond mandibular premolar
most common

lingulal dev groove runs on lingual surface

Y has central pit

Square outline

facial/lingula width=mesiodisatl width
U second mandibular premolar
least commonit


converges linulaly transvers ridge with mesial and distal fossa
H second mandibular premolar
2 cusps each are same size