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Radiology flashcards-Dr Shishir
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Radiology flashcards-Dr Shishir
Intro to radiology prt 1
Study
 Early trials showed that it would require up to 15 minutes to expose a molar tooth, what helped reduce the exposure time to 1-2 minutes?
 improvements in the design of the x-ray tube
what did Dr Kells use for his experiments, and what was the technique?
Dr. Kells used a fluoroscope for his experiments and adjusted the radiation until the bones were visible in the fluoroscope
who is known as the 'Father of Dental Radiography?
Dr. Edmund Kells Jr
why is Dr. Edmund Kells Jr known as the 'Father of Dental Radiography?
because he took the first dental radiograph of a living person in the United States.
who presented the first dental skiagraphs in the USA?
Dr. WJ Morton
the radiographs that Dr Otto Walkoff of Germany took are similar to which modern day radiographs?
bitewing radiographs
how did Dr. Otto Walkoff of Germany took the first dental radiograph?
using a glass photographic plate wrapped in black paper
the first recorded radiographic image was for?
Bertha Roentgen's hand
why did Wilhelm Conrad call his new phenomenon the "x-ray"?
because 'x' is the universal symbol for the unknown, and ray because it traveled in a straight line
Discovery of x-rays
November 8, 1895 - Wilhelm Conrad Roentgen discovered x-rays while researching on the effects of electrical discharge using a Crookes Hittorf tube.
What were the X-ray tubes called in the General Electric company?
Coolidge tubes
In 1920s, the X-ray exposures were reduced to how many seconds in duration?
4-10 seconds
What led to injuries to both patients and clinicians due to high voltage current?
Uninsulated and unprotected wires
What did General Electric introduce to overcome the problem of injuries caused by high voltage current?
Victor CDX shockproof dental X-ray unit
When was the first machine-wrapped dental X-ray film packet introduced by Eastman Kodak company?
1919
Who produced their own rubber film holder with a pocket for holding the dental X-ray film?
Dr. Kells
In what year did Dr. John Marshall Section present a paper on the dangers of radiation at the Stomatology Section of the American Medical Association?
June 1897
What did many early pioneers eventually develop from exposure to tremendous amounts of accumulated radiation?
Fatal cancers
Who demonstrated the first panoramic radiograph in 1933?
Dr. H. Numata, Japan
Who introduced digital imaging into the dental profession at the 1st European Congress of Dental and Maxillofacial Radiology in Geneva in 1987?
Dr. Francis Mouyen
Who are the inventors of Cone Beam CT?
Daniele Godi and Giordano Ronca, Italy
Who is a modern-day leader in dental radiography from the Netherlands?
Dr. Paul van der Stelt
Who pioneered the application of digital imaging into dental practice from the USA?
Dr. Allan Farman
What are the standards for digital imaging and communications in dentistry?
Digital Imaging and Communications in Medicine (DICOM) standards
Intro to radiology prt 2
Study
what does Computerised tomography scan?
hard tissue
which imaging technique provides multiplanar imaging without overlapping?
CT
which extraoral radiographic technique is also known as waters view?
Paranasal sinuses view (PNS)
which radiograph is used mainly for orthodontic purposes to capture a side view of the head and facial structures?
Lateral cephalogram
in occlusal radiography, to get a view of the mandibular arch, where should the machine be placed?
90 degrees, below the oral cavity
in occlusal radiography, to get a view of the maxillary arch, where should the machine be placed?
65 degrees, above the oral cavity
evaluation of pulp treatment, is an indication for which type of radiographs?
IOPA
Radiography
The technique involved in the production of various radiographic images.
Radiology
The interpretation of the radiographic images.
Radiographer
A technician who performs radiographic procedures.
Radiologist
A doctor who specializes in interpreting and diagnosing radiographs.
Oral radiology
Also known as maxillofacial radiology, it is the branch of radiology that focuses on imaging the oral and maxillofacial regions.
what does Radiology use?
Ionizing radiation for diagnostic purposes. It involves the use of imaging techniques such as X-rays, CT scans, and fluoroscopy.
Imaging
The process of producing visual representations of the interior of a body for clinical analysis and medical intervention. It uses both ionizing and non-ionizing radiation.
Oral and Maxillofacial imaging Classification
Includes intraoral and extraoral imaging. It aids in diagnosing dental and oral health conditions.
Intraoral imaging
Includes techniques that involve placing the imaging sensor or film inside the mouth to capture images of the teeth and surrounding structures.
Intraoral periapical radiographs (IOPA)
Also known as periapical radiographs, they capture the entire tooth from the crown to the tip of the root and the supporting bone.
Indications of IOPA:
Includes determining the status of periapical region in deciduous and young permanent teeth, evaluation of pulp treatment, detection of developmental anomalies, identification of pathology in primary teeth, evaluation of periodontal ligament and alveolar bone, diagnosis of traumatic injuries, etc.
which intraoral radiographic technique captures the crowns of the upper and lower teeth in occlusion, provides a view of the interproximal areas for detecting caries and bone loss?
bitewing
Occlusal radiograph
An intraoral radiographic technique that captures a broad view of the maxilla and mandible, providing information on the positioning of teeth and identifying pathology in the jaw.
which Advanced intraoral imaging tool does not require chemical processing of films?
digital imaging sensors
OPG (Orthopantomogram) is also known as?
panoramic radiograph.
PA (Posteroanterior) view is mainly used for what?
mainly used for the post-traumatic examination of the skull.
Magnetic resonance imaging (MRI)
An advanced imaging modality that uses a magnetic field and radio waves to produce detailed images of the body's organs and structures, particularly useful for soft tissue imaging.
Ultrasound
An advanced imaging modality primarily used for imaging cervical lymph nodes in the neck region, utilizing non-ionizing radiation.
Which type is imaging is used for salivary glands?
ultrasound
CBCT stands for:
Cone beam computerized tomography
CBCT Main advantage is that?
Significantly less radiation dose when compared to CT
MRI Main advantage is:
imaging of soft tissues
Ultrasound Mainly used for
imaging of cervical lymph nodes in the neck region
physics of X-rays
Study
what is the Composition Of Matter?
up quarks, down quarks, and electrons.Â
Up quarks and down quarks combine to form what?
neutrons and protons in atomic nuclei
what do protons consist of? what is their charge?
two up quarks and one down quark. their charge is +1
what do neutrons consist of? what is their charge?
one up quark and two down quarks. their charge is neutral
what are the 2 forms of radiation?
1.Particulate radiation, and, 2.Electromagnetic radiation
which radiation is generated when the velocity of an electrically charged particle is altered?
Electromagnetic radiation
what are X-rays?
X-rays are wave packets of energy of electromagnetic radiation that originate at the atomic level (photons)
how do X-rays travel in free space? and at what speed?
 X-rays travel in straight lines at a velocity of 3x10^8 m/s
what is the inverse square law?
inverse square law: Intensity = 1/d^2 (intensity of an X-ray beam depends on the distance of the measuring device from the focal spot).
X-rays Penetrating Power
No medium is required for propagation. The energy carried by X-rays can be attenuated by absorption and scattering by matter. Shorter wavelength X-rays have higher penetration capacity.
which 2 x-ray interactions contribute to image formation?
photoelectric absorption and compton scattering
why can x-rays cause subsequent biological damage in living tissue?
due to their ability to produce ionization
how do x-rays produce a visual image?
by  affecting photographic emulsionÂ
Bremsstrahlung (Braking Radiation)
The amount of deceleration and degree of deflection determine the amount of energy lost when an electron traveling from the anode nucleus very close to the nucleus. X-rays are produced due to this energy loss.
in photoelectric absorption, what can the high energy ejected photoelectrons cause?
ionization interactions, which can damage living tissue
percentage of coherent scattering
7%
continuous Spectrum
The possible wide range of wavelengths of electromagnetic radiation.
Characteristic Radiation
X-rays produced when an electron falls into a lower energy level in an atom.
in photoelectric absorption, the high energy ejected photoelectrons act like what?
like the original high energy x-ray photon
Coherent Scattering
A type of scattering in which the waves remain in phase during the interaction.
the electrons bombarding the anode produce what?
heat majorly, and a small fraction is let out as X-rays
percentage of photoelectric absorption
27%
Photoelectric Absorption
The process by which the energy of an X-ray photon is totally absorbed by an atom, resulting in the ejection of an inner shell electron.
percentage of compton scattering
57% (highest)
Compton Scattering
A type of X-ray interaction in which a photon transfers some of its energy to an outer-shell electron, resulting in the photon being scattered at a lower energy.
What are the 2 phenomena that produce x-rays at the anode?
1. Bremsstrahlung (braking radiation) contributes to the majority of X-ray production, and 2. Characteristic radiation contributes to only a small fraction of X-ray production.
X-ray machines
Study
Circular collimator restricts the size of x-ray beam to how much?
7cm
Collimator
a metallic barrier with an aperture in the middle used to restrict the size of the x-ray beam and the volume of tissue irradiatedÂ
How is added filtration obtained?
by placing aluminum disc in the path of the x-ray beam
Inherent filtration occurs inÂ
glass wall of the x-ray tube, and insulating oil
Effects of low energy x-ray beams:
Do not contribute in image formation, and cause increased radiation exposure to a patient.
What helps in removing the low energy x-ray beams?
Filtration
more tube current
more photons
more exposure time
more photons
Which units are full wave rectified and have a constant potential?
Newer units
which units are half wave rectified?
Older units
Wave rectification
converts alternative current to a more stable current Â
How much is the average tube voltage?
Intraoral and panoramic is around 60 and 90 kVp, and in CBCT around 90 to 120 kVp.
Tube voltage
potential difference between anode and cathode
How much is the average tube current?
About 10 mA
Tube current
flow of electrons from the cathode filament across the tube to the anode.
Which power supply reduces the voltage of the incoming alternating current (AC) to about 10 volts in the filament circuit?
filament transformer
Which power supply provides a high voltage, required between the anode and cathode to give electrons sufficient energy?
autotransformer
Why is copper is used for embedding tungsten in anode?
to dissipate heat generated during production of x-raysÂ
Anode properties
 high atomic number (74), high melting point (3422°C), high thermal conductivity, low vapour pressure
Anode function
converts kinetic energy of the electrons emitted from cathode to X-ray photonsÂ
Anode is made up of
Tungsten embedded in copper stem
the cathode filamentÂ
lies in focusing cup, it is negatively charged, made of Molybdenum, and is concave in shapeÂ
Cathode is made up of
Tungsten in the form of coil about 2mm in diameter and 1 centimeter in length
what is the source of electrons?
the cathode
Main components of the control panel
The mains on/off switch and warning light, the time selector, film speed selector, patient size selector, kilovoltage selector , and the milliamperage switchÂ
what is a disadvantage of the long-metallic rectangular spacer cone?
it can cause many errors.
which beam indicating device is the best? and why?
The long-metallic rectangular spacer cone. due to it being of a similar size to the film, which help radiation not reach unnecessary parts of he patient.
which beam indicating device is used the most?
The short-metallic open ended spacer cone
what is the collimator made of?
lead
what is the material used in filter of the tube head?
aluminum
X-ray dosage
Study
Natural sources of radiation:
Cosmic radiation from the earth’s atmosphere, gamma radiation from the rocks and soil, ingestion of radioisotopes, and inhalation of radon gas and its decay products.
Artificial sources of radiation:
Fallout from nuclear explosions, radioactive waste discharged from nuclear establishments, Medical and dental diagnostic radiation, and radiation from occupational exposure
Dosimetry
Measurement of radiation.
(D) in dosimetry stands for
Radiation absorbed dose, measured in Joules/Kg, and is called Gray (Gy)
(HT) in dosimetry stands for
Equivalent dose, measured in Joules/Kg, and is called sievert (Sv)
Equivalent dose (HT) calculation
Equivalent dose (HT) = radiation-absorbed dose (D) Ă— radiation weighting factor (WR) in a particular tissue
radiation weighing factor in X-rays, gamma rays, and beta particles is:
WR=1
radiation weighing factor in alpha particles is:
WR=20
(E) in dosimetry stands forÂ
Effective dose, and is called Sievert (Sv)
Effective dose (E) calculation
 Effective dose (E) = Σ Equivalent dose (HT) in each tissue × relevant tissue weighting factor (WT)
 tissues that have a relevant tissue weighting factor of 0.12 are:
Bone marrow, breast, colon, stomach, and the lung.
tissues that have a relevant tissue weighting factor of 0.01 are:
bone surface, brain, kidneys, skin, and the salivary glands
tissues that have a relevant tissue weighting factor of 0.05 are:
Oesphagus
tissues that have a relevant tissue weighting factor of 0.08 are:
Gonads
tissues that have a relevant tissue weighting factor of 0.04 are:
Bladder, liver, and thyroid
How to determine effective dose?
by using a tissue equivalent anthropomorphic phantom with dosimeters placed in the most radiosensitive regions.Â
effective dose of Bitewing and periapical radiographs is:
0.0003-0.022 mSv
effective dose of panoramic radiographs is:
0.0027-0.038 mSv
effective dose of Dento-alveolar CBCT is:
0.01-0.67 mSv
effective dose of Craniofacial CBCT is:
0.03-1.1 mSv
Annual dose limits for classified workers( receive high levels of exposure to radiation):
20 mSv
Annual dose limits for Non-classified workers( receive low levels of exposure to radiation):
6 mSv
Annual dose limits for general public( everyone who is not receiving a radiation dose either as a patient or as a radiation worker, but who may be exposed inadvertently):
1 mSv
What are dosimeters? and what are their forms?
Instruments used to measure radiation dose, found in the form of badges and rings
what does TLD stand for?
Thermo luminescent dosimeter
What substances does TLD contain?
calcium and lithium fluoride
TLD principle
absorbs x-ray energy and stores it when the user is wearing it, then uses heat to generate light
Where does the name ( thermo luminescent) come from in TLD?
After heating the material in the laboratory, the heating causes it to liberate light which is equal to the amount of x-ray it absorbed
What does OSL stand for?
Optical stimulated luminescence dosimeter
OSL principle
absorbs x-ray energy and stores it when the user is wearing it, then uses lasers to generate light
