Exam 1 Flashcards
anything that occupies space and has mass
matter
results when matter is altered
energy
substances made up of only one type of atom
elements
central nucleus + orbiting electrons
atom
core of atom, consists of protons and neutrons
- always positively charged
nucleus
positively charged particles
Protons
particles with no charge
neutrons
tiny, negatively charged particles
- Arranged around nucleus in orbits
electrons
pathway of electrons
Orbits (shells)
number of protons and neutrons in nucleus
Mass number/Atomic weight
number of protons in nucleus equals number of electrons in atom
Atomic number
Maximum number of shells per atom
7
1 KeV =
1000 eV
attraction between the positive nucleus and negative electrons
- Keeps electrons surrounding nucleus
Electrostatic force
amount of energy needed to remove electron from its orbit
Binding energy/force
two or more atoms joined together by chemical bonds
Molecules
sharing electrons in outermost shell
Covalent bonding
transfer of electrons
Ionic bonding
can exist as neutral or unbalanced
atoms
(unbalanced atom) atom that gains/loses an electron and becomes electrically unbalanced
ion
converting atoms into ions/production of ions, become positively or negatively charged
Ionization
result of an electron being removed from atom, positive ion + negative ion
Ion pair
emission and propagation of energy through space or substance in form of waves or particles
Radiation
process of unstable atoms undergoing spontaneous disintegration to become balanced
Radioactivity
high energy capable of producing ions
Ionizing radiation
tiny particles of matter traveling in straight lines at high speed, may be charged
- HAS mass
Particulate radiation
- wave like motion
- NO mass
- Can be man-made or naturally
- Arranged on electromagnetic spectrum
Electromagnetic radiation
- discrete bundles of energy
- Photons
- No mass
- Travel as in straight line
Particle concept
- waves
- Focus on wavelength, frequency, velocity
wave concept
distance between crest of waves
Wavelength
number of wavelengths in specific time period
Frequency
wave speed
velocity
o Invisible
o No mass
o No charge
o Travel in waves and straight lines
o High frequency, short wavelength
o Cannot be focused to a point
o Penetrate gases, liquid, and solids
o Absorb matter
o Interact with matter, cause ionization
o Cause certain substances to fluoresce
o Can produce image on receptor
o Causes biological change in cells
Characteristics of X-rays
what does the metal housing in the tubehead do
protect everything
what does the insulating oil in the tubehead do
dissipates heat
what does the tubehead seal do
makes sure insulating oil is contained
what does the aluminum disks do in the tubehead
filters out long wavelength or low frequency x-rays
what does the lead collimator do in the tubehead
restricts size of x-ray beam
Supply electrons necessary to generate x-rays
Cathode (negative)
- Generates electrons
- Creates electron cloud
Tungsten filament
- Focusing electrons into one line
- Electrons always floating from cathode to anode!!
Molybdenum cup
- Convert electrons into x-rays
- Tungsten target
- Copper stem
Anode
needed to generate x-rays
electricity
flow of electrons through a conductor
Electrical current
electrons flow in one direction through conductor
Direct current
electrons flow in two, opposite directions
Alternating current
converting from AC to DC
Rectification
number of electrons moving through conductor
Amperage
speed of electrons moving from cathode to anode
Voltage
path of electrical current
Circuits
- Generates source of electrons needed to produce x-rays at filament of x-ray tube
- Controlled by mA settings
Filament circuit (3-5V)
- Provides high voltage required to accelerate electrons from cathode to anode
- Controlled by kV settings
High-voltage circuit (65,000-100,000V)
device used to increase or decrease voltage in an electrical circuit
Transformer
Decreases V
Step-down transformer
Increases V
Step-up voltage
Corrects minor fluctuations in current
Autotransformer
release of electrons from tungsten filament when electrical current passes through it and heats filament
Thermionic emission
- Aka breaking or bremsstrahlung radiation
- 70% of x-rays produced at anode
- High speed down when passing tungsten atom
- Hits: all kinetic energy converts to high-energy x-ray photon
- Misses: low-energy x-ray photon
General radiation
- 30% of x-rays
- High-speed electron dislodges inner-shell electrons from tungsten atom
- Causes ionization
- Electrons rearrange, causing loss of energy and production of x-ray photons
Characteristic radiation
penetrating x-ray beam
Primary radiation
result of primary beam interacting with matter, less penetrating than primary
Secondary radiation
form of secondary, deflected x-rays after interaction with matter going in all directions; detrimental
Scatter radiation
o Passes through atom unchanged and leaves atom unchanged
o Responsible for producing densities
o Makes dental radiography possible
No interaction
o Photoelectric effect
o Photon interacts with inner shell electrons of matter
o Photon is absorbed and electron is ejected
o Ionization occurs → BAD
Absorption
o AKA modified scatter
o Compton effect
o Photon interacts with outer shell electrons of matter
o Photon loses energy but electron still ejected
o Ionization still occurs → BAD
Compton Scatter
o AKA Thompson Scatter or unmodified scatter
o Photons interact with outer shell electrons, but matter is not altered
o Photons continue to travel with no loss of energy
- Direction changes with no energy loss
o No ionization occurs
Coherent Scatter
the study of the effects of ionizing radiation on living tissue to understand the harmful effects of x-radiation
Radiation biology
- Photoelectric effect or Compton scatter
- Results in positive atom and dislodged negative electron
- Ejected electron still in motion and interacts with other atoms
Ionization
- uncharged neutral atom/molecule that exists with one single electron in its outmost shell
- Highly reactive and unstable
Free radical formation
Cell damage can occur when ionizing radiation directly hits critical areas (cell death)
Direct theory (1/3)
X-ray photons absorbed within cell and cause formation of toxins (causing direct damage)
Indirect theory (2/3)
o Probability of occurrence increases with dose
o Severity is NOT dependent on dose
o All or none
Stochastic radiation effect
o Severity of damage dependent on dose
o Occur only after exceeding threshold
o Result of severe cell damage
Nonstochastic/Deterministic radiation effect
time to exposure to clinical signs
Latent period
time in which cellular injury occurs
Period of injury
time in which it takes for cell to repair itself
Recovery period
o Total dose
o Dose rate
o Amount of tissue irradiated
o Cell sensitivity
o Age
Determinants for radiation injury
- Seen within minutes, days, or week
- Large amount of radiation in short time
Short-term effects
- Appear after years, decades or generations
- Small amount of radiation over long period of time
Long-term effects
- All cells except reproductive cells
- Injury to person irradiated
- NOT passed to offspring
Somatic effects
- Reproductive cells
- Not seen in person irradiated
- Passed onto future generations
Genetic effects
o Blood cells
o Bone marrow
o Reproductive cells
o Intestinal mucosa
o Skin
o Lens of eyes
o Oral mucosa
Radiosensitive cells
o Muscle tissue
o Nerve tissue
o Mature bone/cartilage tissue
o Salivary glands
o Thyroid glands
o Kidney
o Liver
Radioresistant cells
Amount of radiation in air
Roentgen (R)
Roentgen (R)
Exposure
Amount of radiation absorbed by tissue
Radiation absorbed dose (rad)
Radiation absorbed (rad)
Dose
Measurement of the effect on tissue
Roentgen equivalent (in) man (rem)
Roentgen equivalent (in) man (rem)
Dose Equivalent
1 Gy =
100 rad
1 Sv =
100 rem
Medical radiation (medical imaging, dental imaging)
Synthetic
Risk of Cancer from dental imaging
3/1 million
risk of Random cancer
3300/1 million
Who discovered x-rays in 1895?
Wilhem Roentgen
German dentist
Otto Walkhoff
Energy carried by waves/particles
Radiation
high-energy radiation produced by a collision of a beam of electrons with a metal target in an x-ray tube
X-radiation
energy that penetrates substances
X-ray
the study of radiation in medicine
Radiology
image produced on a receptor by exposure to ionizing radiation (2D image of 3D object)
Radiograph
Image created via x-rays passing through teeth
Dental radiograph
Art and science of making radiographs
radiography
production of radiographs of teeth and adjacent structures
dental radiography
person who positions, exposes, and processes dental x-ray image receptors
Dental radiographer
picture of an image
Image
recording medium
image receptor
creation of images of dental anatomic structures for diagnostic purposes
dental imaging
What houses the x-ray tube?
Tubehead
What restricts size of x-ray beam?
Position-Indicating device (PID)
What houses electrical wires and allows for movement?
extension arm
What regulates x-ray beams?
Control panel
What do we control on the control panel
timer
kilovoltage
milliamperage
What makes sure PID is lined up properly?
Beamaliment device
The dark/black portion of a radiograph
Radiolucent
Light/white portion of radiograph
Radiopaque
Overall darkness of an image
density
Difference in degrees of blackness on a an image
Contrast
Never intersect
parallel
lines cross at some point
Intersecting
cross directly in the middle
perpendicular
imaginary line that dives tooth in half
long axis of tooth
central portion of the primary beam of x-radiation
central ray
distance between tooth and receptor
object receptor distance
distance between x-ray source and receptor
target-receptor distance
What x-ray equipment do we use?
XCP-ORA
what are the advantages of paralleling?
accuracy
simplicity
duplication
what are the disadvantages of paralleling?
receptor placement
discomfort
What radiograph examines crown of maxillary and mandibular teeth?
bitewings (BMX)
What radiograph examines the crown, CEJ, root apex, and surrounding areas?
periapicals
What radiograph is used mainly for the diagnosis of dental caries?
Bitewings
What radiograph is mainly used to detect periodontal disease, pathology, endodontic therapy, and implants?
Periapicals
What radiograph examines large areas of maxilla and mandible?
occlusal
disease causing microorganism
pathogen
pathogens in blood
bloodeborne pathogens
objects that penetrate skin
sharps
waste including blood, blood products, contaminated sharps, microbiologic products
Infectious waste
substance inhibiting growth of bacteria
Antiseptic
chemical/physical procedure to inhibit or destroy pathogens (does not kill spores)
disinfect
chemical/physical procedure to destroy all pathogens (includes resistance bacteria and spores)
sterilize
absence of pathogens
asepsis
contact with blood/infectious material involving skin, eye or mucous membranes resulting from procedure performed by dental professional
Exposure incident
exposure from piercing or puncturing skin
Parenteral exposure
standard of care designed to protect personal and patients from pathogens
standard precautions
o Direct contact with
contaminants
o Indirect contact
o Direct contact with
airborne
routes of disease transmission
What is the recipe for infection?
Susceptible host
o Pathogen
o Portal
routine handwashing, antiseptic handwashing, antiseptic hand rub
methods of hand hygiene
The sensor is oriented ______ when exposing a posterior periapicle?
Horizontally
What are the three principles of paralleling technique?
- receptor has to be parallel to long axis of tooth
- central ray must be directed perpendicular to the long axis of tooth and receptor
- A beamalime device must be used to maintain parallelism
How many mSv of radiation can an occupational exposed person be exposed to each year?
50 mSv
What are the two mechanisms of radiation injury?
Ionization
Free radical formation
If subject thickness is increased, how will the image appear?
Darker
X-ray machines operating above 70 kVp should have how many mm of aluminum filtration?
2.5 mm
What type of interaction occurs when an x-ray photon interacts with an inner shell electron and causes ionization?
Absorption
An x-ray beam should be no longer than how many inches after exiting the PID?
2.75 inches
Name five characteristics of x-rays.
Invisible
No mass
No charge
High frequency
Absorb matter
Would a deep large dose of radiation be more likely to cause short or long term effects?
Short term effects
What measurement determines the amount of radiation in the air, and what are the units?
Exposure
Roentgens
What type of radiation results when the primary beam interacts with matter?
Secondary radiation
What does ALARA stand for?
as low as reasonably achievable
Decreasing target receptor distance will result in what to the final image?
Image magnification and loss of definition
An exposure to contaminants by piercing or puncturing the skin is called what?
Parenteral exposure
What measures the speed of electrons moving from cathode to anode?
Voltage or kilovoltage
The central ray of the x-ray beam not being centered on the receptor will cause what error?
Cone cut
What are the four critical organs?
Thyroid gland
bone marrow
skin
lens of eyes
Are somatic effects seen in the person irradiated or their children?
person irradiated
Who prescribes dental radiographs?
dentist
How often should an adult with high caries risk get radiographs done?
every 6-18 months
How often should children with low caries risk get radiographs done?
every 12-24 months
What is the protection equipment of the tubehead?
Filters
collimators
PID
primary beam passes through glass window, insulating oil, and tube head seal
Inherent filtration
How much aluminum is in inherent filtration?
0.5-1.0mm
aluminum disks between tube head seal and collimator
added filtration
How many increments in added filtration?
0.5mm
inherent + added filtration
total filtration
What are the guidelines for less than or equal to 70 kVp of total filtration?
1.5mm aluminum filtration
What are the guidelines of greater than 70 kVp of total filtration?
2.5mm aluminum filtration
o Lead plate with hole or
beam
o Restricts beam size and
shape
o Reduce patient exposure
o Round or rectangular
Collimation
What is the length of a short x-ray beam?
8 inches
What is the length of a long x-ray beam?
16 inches
protect any blood forming and reproductive tissues from scatter radiation
lead apron
protects thyroid gland from scatter radiation
thyroid collar
most effective method of exposure
digital imaging
What is the fastest speed film?
F
radiation emitted from tube head that is not the primary beam
leakage radiation
- measures amount of radiation reaching the body of radiographers
- waist level or higher
personnel monitoring
What is the maximum radiation dose per year for a non-occupationally exposed person?
1 mSv
What is the maximum radiation dose per year for pregnant persons?
0.5 mSv
