p.9
Radiation Risk and Safety
What is the principle of 'no dose without risk' in radiation safety?
It emphasizes that any exposure to radiation carries some level of risk.
p.19
Hand Held X-Ray Devices and NOMAD Training
What factors must be set before taking an X-ray?
Select adult or child, film, PSP, or sensor, and Ant, Post, or BW.
p.15
Radiographic Interpretation Principles
What is the significance of gray level in radiographic images?
Gray level relates to contrast, which is relative.
p.7
Radiation Risk and Safety
What is the effect of radiation on microvasculature?
It leads to reduced oxygenation of distal cells and tissues, causing infarction and fibrosis.
p.15
Radiographic Interpretation Principles
What should be commented on regarding the diagnostic quality of an image?
Any artifacts present in the image.
p.19
Hand Held X-Ray Devices and NOMAD Training
What should you check for before operating a Hand Held X-ray device?
Check for power using the battery indicator.
p.6
Radiation Absorption and Biology
What does the Gray (Gy) unit measure?
Absorbed dose for any type of radiation, but does not describe biological effects.
What advancement occurred in February 1896 regarding X-rays?
Shorter exposure time of 9 minutes was used for foreign body localization.
p.6
Radiation Absorption and Biology
What factors influence absorption kinetics?
Absorption coefficient (z-value) and thickness of the absorber.
p.19
Hand Held X-Ray Devices and NOMAD Training
What is a convenience benefit of Hand Held X-ray devices?
Patients don’t need to be moved to a separate room.
What is the purpose of the focusing cup in the X-ray tube?
It helps focus the electron stream towards the anode.
What type of electricity source is used in X-ray generators?
Alternating current (A/C).
p.7
Radiation Absorption and Biology
What are the two fates of free radicals?
Dissociation and cross-linking.
p.15
Radiographic Interpretation Principles
How do advanced imaging techniques like CBCT differ from conventional radiographs?
CBCT provides true 3D images, while conventional radiographs are 2D.
What did William Coolidge develop in 1913?
Ductile tungsten and the 'hot' cathode tube.
p.3
Radiation Physics and Definitions
How do X-rays travel?
In a straight line; can be deflected or scattered.
p.17
Selection Criteria for Radiographic Exams
What is the purpose of using occlusal exams?
To identify anomalies, occult disease, salivary stones, and jaw expansion.
p.3
Radiation Absorption and Biology
What is the ionizing capability of X-rays?
They interact with materials they penetrate and cause ionization.
p.14
Radiation Risk and Safety
What is a disadvantage of using digital imaging in terms of cost?
Digital imaging can be expensive initially and long-term.
p.12
Image Quality and Shadow Casting Principles
What kVp setting is recommended for contrast in caries detection?
70 kVp (low kVp, high contrast).
p.12
Image Quality and Shadow Casting Principles
What settings are optimal for resolution and distortion?
Shortest object-receptor distance (ORD) and longest target-object distance (TOD).
p.15
Radiographic Interpretation Principles
What is the relationship between x-ray attenuation and radiographic density?
Differences in x-ray attenuation result in differences in radiographic density.
p.7
Radiation Risk and Safety
Which cells are more radiosensitive?
Less differentiated cells, such as bone marrow cells.
What is the role of the anode in the X-ray tube?
It serves as a tungsten target for the electrons, converting their kinetic energy into X-rays.
p.12
Image Quality and Shadow Casting Principles
What is the relationship between penumbra size and focal spot size?
A large focal spot results in a large penumbra, while a small focal spot results in a small (or no) penumbra.
p.17
Selection Criteria for Radiographic Exams
What are common intraoral exams for high-resolution imaging?
Bitewings (BW’s) and periapical (PA’s) plus full mouth series (FMX).
What is Bremsstrahlung radiation?
It is radiation produced when high-energy electrons are slowed in the presence of an atom's electric field, releasing energy.
p.3
Radiation Absorption and Biology
What factors affect the absorption of X-rays?
Density of the subject and energy of the ray.
p.17
Radiation Risk and Safety
What is the radiation exposure level of a panoramic exam?
Approximately 10 times that of a periapical exam.
p.11
Image Quality and Shadow Casting Principles
What is the second principle of shadow casting?
X-ray source must be perpendicular to both object and receptor.
p.3
Radiation Absorption and Biology
What effect do X-rays have on certain substances?
They can cause certain substances to fluoresce.
p.11
Image Quality and Shadow Casting Principles
What is the fourth principle of shadow casting?
Object and receptor should be as close as possible.
p.3
Radiation Risk and Safety
What effect do X-rays have on living tissue?
They can cause biological changes.
p.2
Radiation Physics and Definitions
What is binding energy?
The work required to remove an electron from an atom.
p.15
Radiographic Interpretation Principles
Why is it important to record radiographic findings?
For quality care and legal aspects.
p.7
Radiation Risk and Safety
When is the risk to a fetus greatest from radiation exposure?
In the 1st and 2nd trimester.
p.9
Radiation Risk and Safety
What is the relationship between radiation dose and cancer risk?
Higher doses increase the chance of developing cancer.
p.1
Radiation Risk and Safety
What condition affected radium watch-dial painters in the 1930s?
Mandibular Osteogenic Sarcomas due to licking radium on brushes.
p.10
Radiation Risk and Safety
What should you provide if a patient specifically asks about cancer risk?
An estimate of cancer risk.
What is the function of the timer in an X-ray generator?
Controls the duration of exposure and the time high-voltage is applied to the tube.
p.18
Hand Held X-Ray Devices and NOMAD Training
What should you do if the NOMAD handset has a low battery?
Charge the handset, as it will not emit x-rays with low battery.
p.18
Hand Held X-Ray Devices and NOMAD Training
What is the purpose of the 'Duty Cycle' in NOMAD operation?
To avoid overheating by managing cycle time between exposures.
p.18
Hand Held X-Ray Devices and NOMAD Training
How should the NOMAD device be cleaned?
Wipe down between patients; do not spray directly on the device or charger.
p.13
Digital Imaging Technologies
What is a hard sensor in intraoral systems?
An internal microchip that must be used with a barrier and allows for 'hot-swap' connection.
p.16
Selection Criteria for Radiographic Exams
Who first described selection criteria for dentistry?
Valachovic and Lurie in 1980.
p.7
Radiation Absorption and Biology
How does Low LET radiation interact with water?
It overcomes the binding energy of electrons, ionizing and ejecting them.
p.6
Radiation Absorption and Biology
What is the effective dose used for?
To normalize overall health effects of irradiating specific body parts, expressed in Sv.
p.15
Radiographic Interpretation Principles
What are conventional radiographs considered in terms of dimensionality?
Conventional radiographs are 2D images that represent superimpositions.
What is the function of the cathode in the X-ray tube?
It contains a coiled tungsten wire filament that releases outer shell electrons through thermionic emission.
p.15
Radiographic Interpretation Principles
What are some key elements to consider in the perception of a radiographic image?
Recognition of familiar patterns, resolution of image details, and understanding 2D representation of 3D objects.
Why is tungsten used in X-ray tubes?
Tungsten is ductile, has low thermal expansion, a high atomic number, and a high melting point, making it suitable for X-ray production.
p.17
Selection Criteria for Radiographic Exams
What is the recommended radiographic approach for new pediatric patients?
Assess diseases and development with posterior BWs if disease is suspected.
p.14
Radiation Risk and Safety
What is a benefit of using HIPAA compliant cloud servers for digital imaging?
They ensure data safety and compliance with privacy regulations.
p.13
Digital Imaging Technologies
What is a potential drawback of digitizing conventional films?
There is a likelihood of loss of information.
p.16
Radiation Risk and Safety
What is the goal regarding radiation use in radiographic exams?
Use the least amount of radiation as possible.
p.2
Radiation Physics and Definitions
What is the relationship between wavelength and energy?
Longer wavelength = lower energy; shorter wavelength = higher energy.
p.18
Radiation Risk and Safety
What is the dosage for whole body exposure with NOMAD?
0.12 - 0.3 mSv (sensor vs. D-speed film).
p.6
Radiation Absorption and Biology
What does the unit Roentgen (R) measure?
Ionization in air caused by gamma or x-rays, used clinically to measure exposure in air.
p.9
Radiation Risk and Safety
What are stochastic effects of radiation?
Effects where the probability of occurrence is dose-dependent, such as radiation-induced cancer.
p.6
Radiation Absorption and Biology
What is the direct effect of photon energy on biological molecules?
Photon energy is deposited directly in biological molecules, resulting in damage.
p.9
Radiation Risk and Safety
Which populations are considered sensitive to radiation exposure?
Conceptus, children, and individuals with immune deficiency disorders.
p.1
Radiation Risk and Safety
What health hazards were associated with early X-ray use?
Leukemias in medical radiologists and squamous cell carcinomas in physicians and dentists.
p.14
Radiation Risk and Safety
What is a disadvantage of digital imaging related to patient comfort?
Receptor size can cause discomfort to patients.
p.17
Selection Criteria for Radiographic Exams
What type of imaging is used for broad coverage in extraoral exams?
Panoramic (Pano) imaging.
p.16
Radiographic Interpretation Principles
What do radiographs reveal?
The effect or aftermath of disease, not the disease itself.
p.11
Image Quality and Shadow Casting Principles
What does SOD/TOD refer to in shadow casting principles?
Source and object should be as far apart as possible.
p.10
Radiation Risk and Safety
What is the benefit of using photostimulable phosphor plates (PSP) in imaging?
They provide a 50-90% dose reduction compared to film.
p.10
Radiation Risk and Safety
What is the purpose of collimation in radiography?
To reduce exposure by 55% and improve image quality.
p.11
Image Quality and Shadow Casting Principles
What does density refer to in radiographic image properties?
Overall degree of blackness on the image.
p.11
Image Quality and Shadow Casting Principles
What are the primary tissue controlling factors for density?
Tissue unit volumetric density (z value) and tissue thickness.
p.11
Image Quality and Shadow Casting Principles
What does contrast refer to in radiographic images?
Difference in densities between adjacent areas.
p.11
Image Quality and Shadow Casting Principles
How does high kVp affect contrast?
It produces lower contrast by penetrating tissues more evenly.
p.7
Radiation Risk and Safety
When does radiation act more intensely on cells?
When the reproductive capacity is greatest and during prolonged mitotic processes.
p.17
Selection Criteria for Radiographic Exams
What does a positive history include?
Previous endo or perio treatment, pain/trauma, and family history of dental anomalies.
p.12
Image Quality and Shadow Casting Principles
What is the primary controlling factor for size distortion (magnification)?
Object-film distance (OFD) and target-film distance (TFD). Smaller OFD and longer TFD result in less magnification.
p.16
Radiographic Interpretation Principles
What is the most important finding in radiographic interpretation?
The absence of a normal structure that should be present.
What is the role of a rectifier in X-ray generators?
Converts A/C to D/C, preventing electron production in the inverse cycle.
p.14
Digital Imaging Technologies
How does the transfer rate of larger data impact digital imaging?
Larger data results in longer transfer times.
p.16
Selection Criteria for Radiographic Exams
What should the prescription of a radiographic exam be based on?
Patient history, clinical exam, and lab findings (where applicable).
p.10
Radiation Risk and Safety
What is the role of primary and secondary protective barriers?
Primary barriers reduce exposure to the usable beam; secondary barriers reduce exposure to leakage radiation.
p.13
Digital Imaging Technologies
What are the two types of extraoral systems mentioned?
Panoramic and Cephalometric systems.
p.7
Radiation Absorption and Biology
What is the primary mechanism of biological damage from diagnostic radiation?
Ionization of water leading to free radical formation.
p.6
Radiation Absorption and Biology
What is the purpose of the Sievert (Sv) unit?
It derives equivalent dose, relating absorbed dose in human tissue to effective biological damage.
p.19
Image Quality and Shadow Casting Principles
What is the benefit of a smaller focal point in X-ray imaging?
It results in better resolution.
What are the differences between a large and small focal spot?
A large focal spot allows better heat dissipation but results in poor image detail, while a small focal spot provides sharper images but has poor durability.
p.12
Image Quality and Shadow Casting Principles
How does the length of the target-object distance (TOD) affect penumbra size?
A long TOD results in a small penumbra.
p.3
Radiation Physics and Definitions
Can X-rays be focused to a point?
No, they cannot be focused to a point; they always diverge.
p.11
Image Quality and Shadow Casting Principles
What is the first principle of shadow casting?
Object and receptor must be parallel.
p.2
Radiation Physics and Definitions
What happens to x-ray intensity as it penetrates material?
It decreases; photons get absorbed, resulting in less energy.
p.11
Image Quality and Shadow Casting Principles
What is the fifth principle of shadow casting?
The focal spot should be as small as possible.
p.3
Radiation Physics and Definitions
What does the Inverse Square Law state about X-ray intensity?
Intensity is inversely proportional to the square of the distance between the source and the point of measure.
p.3
Radiation Physics and Definitions
What happens to X-ray intensity when the distance is increased by 2x?
The intensity decreases by 4x.
p.8
Radiation Risk and Safety
Why is the old paradigm of mutagenic events considered incorrect?
It doesn't explain how radiation cancers can appear decades after exposure.
p.2
Radiation Physics and Definitions
What distinguishes x-rays from gamma rays?
X-rays are produced by bombarding a substance with high-velocity electrons, while gamma rays are emitted by the nucleus of a radioactive substance.
p.15
Radiographic Interpretation Principles
Which heavy metal absorbs the most x-rays?
Lead, due to its high attenuation.
p.9
Radiation Risk and Safety
What does ALARA stand for?
As Low As Reasonably Achievable.
What was significant about December 1895 in X-ray history?
The first radiograph was taken.
p.19
Radiation Risk and Safety
What is the benefit of a smaller cone in Hand Held X-ray devices?
It reduces radiation exposure by 25%.
p.6
Radiation Absorption and Biology
What is the indirect effect of photon energy?
Photon energy is deposited in water, generating energized and radical water species that attack biological molecules.
p.14
Radiation Risk and Safety
How does digital imaging compare to film in terms of radiation exposure?
Digital imaging uses approximately 90% less radiation than D speed film.
p.14
Digital Imaging Technologies
What is a significant advantage of digital imaging regarding image acquisition?
Immediate image acquisition.
What are the steps involved in the production of X-rays?
1. Separation of electrons (Thermionic Emission) 2. Production of high-speed electrons 3. Concentration of electrons (Space charge) 4. Movement of electrons from cathode to anode 5. Sudden stoppage of electron stream.
p.14
Radiation Risk and Safety
What are the environmental benefits of digital imaging?
Elimination of processing equipment and chemicals, and no need for a dark room.
Why must A/C be converted to D/C in X-ray tubes?
A/C will damage the tungsten filament.
p.14
Digital Imaging Technologies
What is a key difference in archiving between film and digital imaging?
Film is an archived record with permanent errors, while digital has many archiving methods.
p.16
Radiographic Interpretation Principles
What is the recommended scanning sequence for reading films?
Start at the upper left and read clockwise.
p.16
Selection Criteria for Radiographic Exams
What factors should be considered when acquiring diagnostic images?
Quality, number and type of images, and viewing conditions.
What type of current does a rectifier produce?
Direct current (D/C), which has unidirectional flow.
What are the two types of circuits in an X-ray generator?
High-voltage circuit and low-voltage circuit.
p.2
Radiation Physics and Definitions
What is ionization?
The production of ions through the ejection of one or more electrons from an atom.
p.18
Radiation Risk and Safety
What should you not do before making an exposure with the NOMAD?
Don’t enable NOMAD pro until ready for exposure.
p.13
Digital Imaging Technologies
How can image resolution be increased?
By decreasing pixel size and increasing dots-per-inch (dpi).
p.19
Hand Held X-Ray Devices and NOMAD Training
How do you lock and unlock the X-ray device?
Press and hold the designated buttons.
p.19
Hand Held X-Ray Devices and NOMAD Training
What happens when the X-ray exposure is complete?
The tone emitted ends, indicating the trigger can be released.
What is thermionic emission?
The process where the filament heats up (~2200 °C) and releases outer shell electrons when current is applied.
p.15
Radiographic Interpretation Principles
What should be included when describing an abnormality in radiographic findings?
Location, size, shape, density, borders, and effect on adjacent structures.
p.17
Selection Criteria for Radiographic Exams
What are some clinical indications for radiographic exams?
Positive history, positive clinical findings, and high caries risk.
p.12
Image Quality and Shadow Casting Principles
What happens when you increase the object-film distance (OFD) using the paralleling technique?
It results in a large penumbra.
p.3
Radiation Absorption and Biology
What can X-rays penetrate?
Liquids, solids, and gases; penetration depends on the composition of the subject.
p.12
Image Quality and Shadow Casting Principles
What is the effect of insufficient beam angulation on image size?
It causes elongation, making the image longer than the object.
p.17
Selection Criteria for Radiographic Exams
What should be considered for symptomatic patients?
Use PA to examine specific sites and other techniques as appropriate.
p.13
Digital Imaging Technologies
What is digitization in the context of imaging?
Representing a particular object (image, diagram, etc.) in the form of numerical digits (binary system).
p.13
Digital Imaging Technologies
What are the two main components of an imaging system?
Source (method for generation of X-rays) and Detector (records the X-ray photons).
p.11
Image Quality and Shadow Casting Principles
What are the geometric factors affecting resolution?
Focal spot size, object receptor distance, and tube object/receptor distance.
p.13
Digital Imaging Technologies
What is the role of image manipulation in digital imaging?
To improve diagnostic accuracy by changing density and contrast, taking measurements, and more.
p.19
Hand Held X-Ray Devices and NOMAD Training
What indicates that the device is ready to take X-rays?
READY + Green indicators.
p.6
Radiation Absorption and Biology
What is Compton Scatter?
A process where a high-energy photon strikes a free outer shell electron, ejecting it and reducing the photon's energy.
p.6
Radiation Absorption and Biology
How does beam hardening affect X-ray beams?
It raises the median and mean energy, increasing the number of photons hitting the receptor and decreasing radiation dose to superficial structures.
p.8
Radiation Risk and Safety
What are the causes of Acute Radiation Syndromes?
Exposure to large, acute doses from weapon detonation, nuclear accidents, or excessive fallout.
p.12
Image Quality and Shadow Casting Principles
What causes shape distortion in radiographic images?
The angular relationship between teeth, receptor, and beam, as well as insufficient or excessive beam angulation.
p.10
Radiation Risk and Safety
What should you avoid saying when discussing radiation risk with patients?
It's nothing, unimportant, or similar dismissive statements.
p.10
Radiation Risk and Safety
What is the radiation dose from a panoramic x-ray?
14.2 μSv (equivalent to 1.7 days of background radiation).
p.16
Radiographic Interpretation Principles
What is the principle behind diagnostic ability in radiography?
"You see what you know" and "You see what you look for."
p.10
Radiation Risk and Safety
What is the effect of increasing kVp from 70 to 90?
It reduces dose by 23% and increases penetration.
p.11
Image Quality and Shadow Casting Principles
What is the most important factor to control for exposure?
mAs (mA multiplied by exposure time).
p.2
Radiation Physics and Definitions
What is linear energy transfer (LET)?
A measure of the energy transferred to a material as an ionizing particle travels through it.
p.13
Digital Imaging Technologies
What can imaging software help to enhance?
Carious lesions and apical resorption, using histogram 'gray scale' data.
What factors control the quantity and quality of the X-ray beam?
Quantity is controlled by exposure time and tube current (mA), while quality is controlled by tube voltage (kVp).
p.12
Image Quality and Shadow Casting Principles
What is the effect of excessive beam angulation on image size?
It causes foreshortening, making the image shorter than the object.
What is the difference between step-up and step-down transformers?
Step-up transformers have more coils in the secondary circuit, increasing voltage; step-down transformers have more coils in the primary circuit, decreasing voltage.
p.10
Radiation Risk and Safety
What should be used to protect patients during radiographic procedures?
Leaded aprons and thyroid collars.
p.18
Radiation Risk and Safety
What guidelines should be followed for pregnant patients and operators?
Follow all radiation safety guidelines.
p.13
Digital Imaging Technologies
What is the resolution capability of human eyes compared to digital images?
Human eyes can detect 4-6 line pairs/mm, while digital images can achieve 10 line pairs/mm.
p.14
Radiographic Interpretation Principles
What is a potential risk associated with digital image manipulation?
It may improve diagnosis of one disease while obscuring another.
p.18
Hand Held X-Ray Devices and NOMAD Training
Are all Hand Held X-ray Devices FDA approved?
No, not all are FDA approved.
p.18
Hand Held X-Ray Devices and NOMAD Training
What are Hand Held X-ray Devices ideal for?
Mobile locations, operating rooms (OR), and emergency rooms (ER) for a few PAs/occlusal images.
p.8
Radiation Risk and Safety
What is radiation hormesis?
An adaptive response where preirradiated human lymphocytes develop fewer chromosomal aberrations after subsequent irradiation.
p.8
Radiation Risk and Safety
What is the bystander effect in radiation exposure?
Irradiated cells signal distress to adjacent cells through direct interactions or chemical mediators.
p.8
Radiation Risk and Safety
What is genomic instability in the context of radiation exposure?
Enhanced rates of mutagenesis and alterations in cellular function or death, considered a hallmark of carcinogenesis.
p.18
Hand Held X-Ray Devices and NOMAD Training
What should you ensure when attaching a handset to the NOMAD?
It should 'click' into place and be secure by pushing towards the backscatter shield.
p.13
Digital Imaging Technologies
What is the purpose of a PSP scanner?
To return trapped electrons to the valence band, emitting laser light that is converted to digital information.
p.2
Radiation Physics and Definitions
How do beta particles differ from alpha particles?
Beta particles are smaller, less energetic, and ejected at high velocity from a nucleus undergoing beta decay.
p.17
Selection Criteria for Radiographic Exams
What is the radiographic recommendation for edentulous adults?
No radiographic exam required unless disease is suspected.
What does the high-voltage circuit do in an X-ray generator?
Connects cathode to anode and aids in the movement of electrons.
What is the function of the low-voltage circuit in an X-ray generator?
Regulates current through the filament, powered by a step-down transformer.
p.2
Radiation Physics and Definitions
What type of particle is an alpha particle?
A positively charged particle with large electrical charge and mass.
p.2
Radiation Physics and Definitions
What is a free radical?
An atom that has an unpaired electron with respect to spin; highly reactive.
p.2
Radiation Physics and Definitions
What is the mass number of an atom?
The sum of protons and neutrons.
p.13
Digital Imaging Technologies
What is the function of a PSP system?
It absorbs X-ray energy, stores it as valence electrons, and later reads it with a laser beam.
p.11
Image Quality and Shadow Casting Principles
What is resolution in the context of radiographic images?
The ability to distinguish between two closely spaced points.
p.11
Image Quality and Shadow Casting Principles
What is penumbra?
The area of unsharpness in the projected shadow of an object.
