Radiology Flashcards
Periapical Radiograph should record the?
Crown, Root and periodical area. Shows 2-3mm periapical area
The Definition of Radiolucent is
Dark or Black area on the radiograph
Radiolucent could be seen as
Air, Soft Tissue, Pulp Canal, areas of Bone Loss
The Definition of Radiopaque is
Light or White area on the radiograph
Radiopaque could be seen as
Enamel, Dentin, Metal Restorations Endo fillings, Bone
Two Types of Radiographs
Intraoral and Extraoral
What are the two reasons for Bitewings?
Alveolar Crest Bone Level, and proximal Caries
Extraoral Bitewing
New Technique: one image for each side of jaw, uses PAN- Therefore extra oral imaging. Records periodical areas
Topographical shows
wide coverage of bone pointing towards note
Cross Sectional shows
Buccal or lingual localization
What is the line that represents an imaginary center of x-ray beam?
Central Ray
Supernumerary is
An extra tooth
Why is intraoral preferred over Extraoral?
A structure or lesion can be recorded entirely on intraoral
Why do we use extraoral?
Disease can’t be covered by intraoral so we use extraoral
Trismus means
Inability to open mouth
Periapical or Bitewing radiographs provide the maximum _________
Detail
When area to be radiographed is larger than can be covered we use ________________
Extraoral Radiograph
Why do we use extra oral radiography?
Disease is located in an area not normally covered by intraoral films, also used for patients who gags on intraoral film
Focal Trough
Grey shaded area or area of focus
The pan records:
Unobstructed, panoramic records of entire mandible, maxilla and associated structures on single radiograph
The pan is the most ______________ extra oral radiograph in dentistry
common
Cephalometric is used to
measure and assess growth
Cephalometric has a fixed ___________ to ___________ Distance of ______in
Source to film distance of 60 in.
Cephalometric Radiography has
the most standardized and reproducible views
Who is the first person in the world to take a dental radiograph?
Otto Walkhoff
In a few sentences, write what inventions led to the discovery of x-rays in 1895?
Three major inventions paved the way for the discovery of x-rays. These are 1) photography and photographic plates, 2) electricity, and 3) light bulbs. Modification of the bulb and energizing the bulb with electricity produced x-rays. These rays were recorded on the photographic plates.
Q5. Unit 1. What was the problem with nitrocellulose films that prompted the development of polyester films? The nitrocellulose films used to
Catch Fire
Which dentist was a pioneer in alerting that radiation was dangerous?
William H. Rollins
Radithor was:
A mix of radium and water
What type of image does not use ionizing radiation
MRI
What are the three types of intraoral radiographs?
Intraoral, Bitewing, and Occlusal
What kind of imaging is a standardized radiograph for measurements?
Cephalometric
The purpose of cross-sectional occlusal radiography is identifying
the buccal or lingual location of an object
What kind of images provide the maximum detail?
Intraoral radiographs
The A number (Atomic mass number) of an atom means the total number of
Protons and Neutrons
The word ionization means
To Create and Ion Pair
With the loss of an electron (negatively charged), the atom becomes positively charged. The process of creating this pair of positive and negative ions is called ionization. The answer is on page 23 of the handout.
An Electron is positive or negative charge?
Negatively Charged
What is Binding Energy?
The binding energy is the force that keeps the electrons in their own orbits. An electron on the inner shell has higher binding energy. The outer shell electrons have lower binding energy. Therefore, it is easier to remove an outer shell electron than an inner shell electron
According to Bohr’s model, what is the maximum number of shells or orbits in an atom
Seven
The Z number (Atomic number) of an atom means the total number of
Protons
What kind of electromagnetic radiation has stronger energy?
Short Wavelength
Which Electron has higher binding energy?
Inner Shell Electron
What is the charge of a Neutron?
No Charge
Of the following radiation, which one has the shortest wavelength?
x-rays
Which is the most common interaction of photons with matter
Compton scattering
How long does radiation stay in the room after radiographic exposure?
Radiation Does not Stay after exposure
During ionization, what is lost from an atom?
The Electron
In Comptons Scattering, which electron is ejected?
The Outer Shell
During the interaction of x-rays, an atom underwent excitation. What happened to the atom?
No Loss of the Electron
In your clinic, the x-ray machine makes a beeping sound during exposure. How loud is the x-ray?
The X-ray has no sound
Which interaction requires more energy
Photoelectric absorption interacts with an inner shell electron. The inner shell electrons have higher binding energy.
What is the role of a step-up transformer?
To multiply the incoming voltage
What is the unit of current?
apmere
What kind of terminal is a cathode?
Negative
What is the unit of Voltage?
Volt (v)
What is the unit of resistance?
Ohm
What kind of energy are you using on your cell phone on your hike in the mountains?
(Direct Energy) During your hike, your cell phone is still using electricity. But the phone is not plugged into the wall. The electricity is coming from the battery. The electricity of the battery is from a DC generator. Please see the answer on page 13 of the handout. When your phone is connected into the wall outlet, you are using alternating current, which is converted into DC through the cell phone battery)
What is the Quantum Model
Positive Charged nucleus at the center, Negatively charged electrons are in 3 dimensional orbitals
(No More than 7 orbits) Orbitals shapes are spherical or lobular.
Bohr Model
shows the atom as a central nucleus containing protons and neutrons with the electrons in circular orbitals at specific distances from the nucleus
An AC generator makes a 60-cycle current. What does this statement mean?
Its flow has 60 peaks or troughs per second
Electrons are arranged in definite energy levels know as
orbits or shells
Orbits are at varying ___________.
distances
Orbits are in alphabet or numbered as
K,L,M,N,O,P,and Q or 1,2,3,4,5,6,7
How Many electrons in each shell?
2n(squared) +2x(orbit number) Squared
Ionization is
Neutral atom loses an electron, the atom becomes positively charged.
Radiation
Transfer of energy through space and matter
Ionizing Radiation is:
Radiation that causes ionization.
What are the two types of Radiation:
Particulate and Electromagnetic
Particulate Radiation is described as:
Particulate Radiation transfer of energy by high velocity subatomic particles. When Particulate radiation passes through any matter, it loses some energy.
The Loss of Energy in Particulate radiation is called
Linear Energy Transfer
______________ Radiation comes from subatomic particles
Particulate Radiation
Electromagnetic Radiation is described as:
Waves of Energy (Transfer of energy through space as a combination of electrical and magnetic fields. )such as : Gamma Rays, X-rays, ultraviolet rays, visible light, TV, radar and microwave.
Electromagnetic Radiation has two theories called:
Wave Theory and Quantum Theory
Wave Theory
Energy is transferred in the form of waves
Quantum Theory
Electromagnetic radiation is considered as “bundles” of energy called photons
Wavelength
Distance between two successive crests or troughs
(Measured in meters or in case of X-rays Angstrom Units)
Long wavelengths have ____________ Energy
Low
Short wavelengths have ___________ Energy
Strong
Light waves that have same color (energy) are _______________
Monochromatic
Light waves that have different colors (energy) are _____________
polychromatic
EMR Wave Theory states that:
Not all light waves/xray waves have same energy
Excitation is
When the transferred energy is not sufficient to overcome binding energy. Electron is not ejected, but the receiving electron is raised to a higher energy level within the orbit.
Photographic Effect
What is the primary type of radiation produced in a dental x-ray machine?
Bremsstrahlung
The role of a low voltage circuit in an x-ray tube is to
Increase the temperature of the cathode components
A 60-cycle x-ray machine means
The x-ray production turns on and off 60 times a second
What is the main risk of high temperature in an x-ray machine?
The filament may disintegrate
In bremsstrahlung radiation, the interaction is
Electron from the cathode interacts with the nucleus of the anode
A step Up transformer is added to the X-ray machine to
modify the penetrability of the x-ray beam
The Duty Cycle is for:
The duty cycle is for minor exposures, for fractions of seconds. For panoramic radiography, we have a longer single exposure. Therefore, the concept of duty cycle is not relevant for panoramic radiography. Although tube rating is mostly for research or investigative purposes, for a long panoramic exposure, tube rating is more important than duty cycle. Please review the concept on pages 25 and 26 of the handout.
In characteristic radiation, the interaction is
Electron interacts with an inner shell electron
What is the primary factor in an x-ray machine that controls the quantity of x-rays before the beam exits the tube head?
Milliampere
Why does a radiographic image become darker if you increase the mA?
More x-ray beam reaches the sensor
After an x-ray exits an x-ray tube, what factor affects the quantity of x-ray?
Filtration
(kilovoltage, milliampere, and time of exposure are factors related to the x-ray tube. After the x-ray beam exits the tube, only filtration will affect the quantity of x-rays reaching the patient’s body. By filtering, we remove the less penetrating x-ray photons. Therefore, a large quantity of radiation reaches the patient’s body)
What kind of radiation should be the primary concern for the well-being of a dental assistant?
Scatter (the scatter radiation can travel in any direction and leads to a unnecessary exposure of the operator)
The purpose of filtration is to
Reduce the radiation dose Filtration removes low energy photons. These photons do not contribute to the image formation and unnecessarily exposes the patient. Therefore, using filtration, we reduce the radiation dose to the patient)
Your radiographs are coming out lighter than the desired diagnostic quality. The settings for kVp and mA are fixed and cannot be changed. What can you do to improve the density of the radiographs?
Increase the exposure time
The main purpose of selecting a greater collimation is
Reduce the exposure to the body parts (collimation is to reduce the size of the x-ray beam. With greater collimation, a smaller part of the body is exposed to radiation)
If you increase kVp, what happens to the x-ray beam?
The beam can cross thicker tissues (kVp primarily controls the quality or penetrability of the radiation. With higher kVp, the more energetic radiation beam can cross thicker tissues)
How can a Dental Assistant benefit from following the principle of inverse square law?
Unnecessary exposure to the operator can be reduced
You are purchasing a new intraoral x-ray machine. In the space below, please write an accessory that can you select to reduce the radiation dose to the patient? Please provide the answer based on the knowledge from this unit.
Most x-ray machines, with a round collimation. If you buy a rectangular collimation (rectangular PID) the radiation dose to the patient will be significantly smaller. I asked you to answer based on knowledge from this unit. The concept is presented on pages 14-16 of the handout of this unit. In a future unit, in unit 24, page 11 of the handout, we will see that FMX with round collimation provides a dose of 85 microSievert, while a rectangular collimation has a dose of only 17 microSievert. This is a significant drop
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients? After radiographing a 10-year-old child, your next patient is a Viking Quarterback
Increase the pulse
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients?After radiographing a 30-year-old man, your next patient is an 83-year-old grandmother
Decrease the Pulse
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients?After radiographing a 30-year-old man, your next patient needs a complete denture
Decrease the Pulse
Your x-ray machine has fixed kV and mA. The only modification allowed is the number of pulses of x-rays. Please indicate how you will adjust the settings for the following types of patients? Your machine had 3 mm Aluminum filter. Your technician replaced the filter with a 4 mm aluminum disc. To get new radiographs with the same density, what step would you take?
Increase the Pulse
Your machine allows adjustment of mA and time. For an ideal exposure, you need 10 mAs. In the spaces below, write what adjustment you will consider for the following patients: A restless child: You have set the exposure time to 1 second. What will be the correct mA for an ideal exposure?
10 mA (10 mA x 1 second = 10mAs)
Q25. Unit 8.. Your machine allows adjustment of mA and time. For an ideal exposure, you need 10 mAs. In the spaces below, write what adjustment you will consider for the following patients: A high school senior. You have set the exposure time to 2 second. What will be the correct mA for an ideal exposure?
5 mA (5 mA x 2 seconds = 10mAs)
Your machine allows adjustment of mA and time. For an ideal exposure, you need 10 mAs. In the spaces below, write what adjustment you will consider for the following patient: A patient with Parkinson’s disease. You have set the exposure time to 0.5 second. What will be the correct mA for an ideal exposure?
20 mA (20 mA x 0.5 second = 10mAs)
Your machine allows adjustment of kVp, mA, and time. For an ideal exposure at 60 kVp, you need 10 mAs. If you increase the kVp to 70, how would you adjust the time of exposure?
Decrease the pulse
Your machine allows adjustment of kVp, mA, and time. For an ideal exposure at 60 kVp, you need 10 mAs. At 60 kVp, you have selected 5 mA. What should be the exposure time?
2 Seconds
The slanting of the anode is to
Assist in the line focus principle
Why is tungsten used as a filament material?
Tungsten has a high insulating property
What is the purpose of oil surrounding the glass tube?
Provide a temperature control to the tube. (during x-ray production, the x-ray tube generates high heat. The oil surrounding the tube helps in cooling the tube. The answer is on page 5 of the handout.)
The cathode component has which of the following features?
Negatively charged with a tungsten filament
The role of focusing cup in an x-ray tube is to
direct the electrons to the focal spot (The negatively charged focusing cup focuses the electrons in an narrow path towards the anode. The concept is described on page 8 of the handout.)
Which of the following choice(s) has lower thermal conductivity
Tungsten
Nucleus has:
protons and neutrons (positively charged)
Hydrogen Atom has
single proton and a single electron
When Matter changes _____________ is ___________
energy is formed
What is one of the benefits of panoramic radiography over FMX?
Lower Radiation (Although panoramic radiography has several advantages over FMX, from the above choices, the lower radiation dose would be the correct answer)
In panoramic radiography, why do machine components move?
to select a specific tissue layer