DanB Radiation and Safety Test Prep Flashcards
What was the problem with nitrocellulose films that prompted the development of polyester films? The nitrocellulose films used to
Catch Fire
What kind of imaging does not use ionizing radiation?
MRI
Write the names of three types of intraoral radiographs
PA, Bitewing, 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
The A number (Atomic mass number) of an atom means the total number of
Protons and Neutrons
The Word Ionization means
The creation of an Ion Pair
Binding Energy Means
Binding energy is the force that keeps the electrons in orbit
According to Bohr’s model, what is the maximum number of shells or orbits in an atom
7
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?
Electron
In Compton’s scattering, which electron is ejected?
Outer Shell Electron
During the interaction of x-rays, an atom underwent excitation. What happened to the atom?
No Loss of Electron
In your clinic, the x-ray machine makes a beeping sound during exposure. How loud is the x-ray?
xray has no sound
Which interaction requires more energy
Photoelectric absorption
What is the role of a step-up transformer?
To multiply the incoming voltage
What is the unit of Current
Ampere
What kind of terminal is a cathode?
Negative
What is the unit of Voltage?
Volt
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 Current
An AC generator makes a 60-cycle current. What does this statement mean?
Its flow has 60 peaks or troughs per second
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
Remember that only after the interaction of electrons with the anode, radiation will be produced. Inside the x-ray machine, the electrons interact with the atoms to generate radiation. In the patient’s body, the radiation will interact with the atoms in patient’s cells)
A step-up transformer is added in an x-ray machine to
modify the penetrability of the x-ray beam
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.
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
mA controls
the quantity of radiation. More radiation reaching the sensor makes the image darker. Please see page 6 of the handout.
After an x-ray exits an x-ray tube, what factor affects the quantity of x-ray?
Filtration
What kind of radiation should be the primary concern for the well-being of a dental assistant?
Scatter
The purpose of filtration is to
Reduce the radiation dose
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
If you increase kVp, what happens to the x-ray beam?
The 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
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 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
The slanting of the anode is to
assist in the line focus principle
Why is tungsten used as a filament material?
Tungsten can tolerate high heat without melting
What is the purpose of oil surrounding the glass tube?
Provide a temperature control to the tube
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
Which of the following choice(s) has lower thermal conductivity
tungsten
What is one of the benefits of panoramic radiography over FMX?
lower radiation
In panoramic radiography, why do machine components move?
to select a specific tissue layer
In panoramic radiography, what is a focal trough?
areas that have objects of interest
In panoramic radiography, collimation is done to
identify the focal trough
generate a narrow beam
DICOM is a term that applies to
digital radiographs and also all clinical imaging
How does the beam shape of the CBCT differ from a panoramic x-ray beam?
(Panoramic radiography uses a narrow x-ray beam. CBCT uses a cone-shaped beam. The answer is on page 2 of the handout.)
What is the full form of MPR?
Multiplanar Reconstruction
What is the difference between pixel and voxel?
(A pixel is a 2D image data while a voxel is a 3D image data.
What does Field of View mean as related to CBCT scans?
The field of view describes the amount of tissues included in a CBCT or a CT scan.
What are the different types of 3D rendering for CBCT images?
Solid surface rendering and semi transparent rendering.
How can you identify if a CBCT scan has motion artifacts?
Primarily, by identifying double outlines of the borders of the bone. Sometimes motion artifacts will also create streaking.
In the space below, please write how the second generation of CT differs from the first generation.
The first generation CT had only one detector. On the 2nd generation CT, multiple detectors were introduced.
What element is most important for creating MRI?
Hydrogen
. In the space below, write the name of a radiographic examination for salivary glands.
A common technique for salivary gland imaging is sialography
What does a Hounsfield Unit represent?
Densities of tissues on CT voxels
two benefits of CBCT over CT.
CBCT has several advantages over CT. The primary advantages are lower radiation dose and cost of the machine/imaging. Other benefits of CBCT are dedicated dental software and lower metal artifacts.
What is the meaning of Windowing for CT?
Selecting a range of densities of tissues on a CT image
What is the distance between the x-ray source and receptor for a cephalometric machine?
60 inches
A radiofrequency pulse is employed to change
the orientation of protons in a tissue
What is the unit for measuring the strength of a magnet?
Tesla
In processing PSP plates, what information is collected by the computer? The amount of
Visible light
For faster image processing, which is the best technology?
CMOS
For analog films, what is the main component of the coating
Silver Bromide
For CCD sensors, what is the principle of data collection?
Electrons move from one pixel to another
What imaging technology employs the bucket brigade concept?
CCD
why you should process PSP plates as quickly as possible.
Room temperature can release trapped electrons in a PSP plate, degrading the data. Therefore, PSP plates should be processed as quickly as possible.
Which factor is more important for identifying a hairline fracture of a root?
Spatial resolution
Which factor is more important for identifying dental caries?
Contrast resolution
What is the purpose of a dot on an intraoral film?
Identifying radiographs from the right or the left side
What is the purpose of a lead foil in an introral film packet?
Reducing scatter radiation
What is the error that caused a dark spot on a processed radiograph?
Contamination of the film with the developer before fixing
A processed radiograph shows tire track marking. What does this mean?
The film packet was reversed during exposure
What is the error that caused a white spot on a processed radiograph?
Contamination of the film with the fixer before developing
In the space below, write what does ‘definition’ mean for a radiographic image
n radiology, definition means the sharpness of a structure as recorded on the image. A well-defined structure has a sharp border. A poorly defined structure has fuzzy border.
write what does ‘distortion’ mean for a radiographic image.
n radiography, distortion means unequal magnification of a structure. Some areas of the tooth is magnified in some area is less magnified. A distorted image does not represent the true shape of the anatomy.
Which of the following radiographs employ the maximum positive vertical angle (+VA)?
Maxillary incisor
Which of the following radiographs employ the maximum horizontal angle?
Molar
One geometric factor that will increase the size of the penumbra of the radiographic image is a:
decreased source to film distance (film-object distance is constant)
On a periapical radiograph, which object is magnified more?
Buccal
On a panoramic radiograph, which object is magnified more?
Lingual
List at least four different ways that you may localize an object in a patient’s mouth using radiography.
The four different ways of localizing an object are, 1) image shift principle, 2) right angle technique, 3) cross-sectional occlusal radiography, and 4) CT or MRI. In addition, we may also employ panoramic radiography to help localize a structure depending on the size of the object.
On an ideal maxillary molar radiograph, which cusps will be closer to the lower part of the image?
Buccal
A structure appears highly radiopaque on a periapical radiograph. This structure is/has
absorbed more radiation
Your patient is a 260 lb football player. What should you do to get a good quality image?
Increase the pulse
A structure appears highly radiolucent on a periapical radiograph. This structure is/has
low chemical density
A radiograph appears ‘washed out’ or light. Your machine does not allow any modification of kVp or mA. What can you do to make the subsequent radiographs darker?
Increasing the time of exposure will improve the density of the radiograph.
Which of the following materials will appear most white or light on a radiograph?
gold crown
What factor of a gutta percha root canal filling makes it whiter than a composite filling on a radiograph
chemical composition
In your x-ray unit, an ideal periapical radiograph of the molars requires ten pulses. By mistake, you increased it to 20 pulses. How would your image look like??
too dark
Your patient has many carious teeth and some faulty restorations. What kind of image contrast will you prefer?
moderate
High contrast or low contrast are not always diagnostic. Therefore, extreme contrast should be avoided.
Your doctor suspects a large cyst in the patient’s mandible. A cyst is a diseased cavity in the bone. What adjustment can you make to your machine to provide an excellent diagnostic radiograph for your doctor? Your machine allows modification of kVp, mA, and pulse.
A bone with his cyst means less tissues. Therefore, lowering the kV, mA or the time of exposure provide us with a diagnostic radiograph.
Your patient has caries, periodontal bone loss, root fracture, and a periapical lesion. How would you process the image?
Increase the brightness
Your patient has many unerupted and several extra (supernumerary) teeth. What would be a quick manipulation of the CBCT scan to show your doctors all the teeth?
A panoramic reconstruction with MIP protocol
Your doctor placed several metal crowns. On a follow-up radiograph, she noticed defective margins of all the restorations. What may have happened?
Over sharpening of the image
A bitewing radiograph was taken to identify proximal caries. However, the caries may be small. What can you do to improve the diagnosis?
Increase the contrast
A patient may have a root fracture. What can you do to the periapical radiograph to improve the diagnosis?
Increased the sharpness
. Please write the proper vertical angle of the following radiographic techniques: Maxillary Molar; Maxillary Incisor; Mandibular molar; Mandibular incisor
a. Maxillary molar: + 30 degrees
b. Maxillary incisor: + 30 degrees
c. Mandibular molar: + 5 degrees
d. Mandibular incisor: minus 15 degrees
Which radiograph should fully record the first maxillary molar
Premolar radiograph
Where should the central ray be pointed for a molar bitewing?
For molar bitewing, the central ray entry should be in the inter-proximal contact between first and 2nd maxillary molars.
List a few reasons that you should not use bisecting angle technique.
There are several reasons for not using bisecting angle technique. The primary reason is creating an imaginary geometry during the technique. In addition, in bisecting angle thinking, the images are often distorted, either elongated or foreshortened.
How can you best establish the patient in the proper focal trough? Select the best choice:
Instruct the patent to bite on the bite block
