Radiography Flashcards
Who discovered x-rays?
What year?
Wilhelm Conrad Roentgen
1895
Who was the first to take a dental radiograph?
What year?
Where?
Dr. Otto Walkoff
1896, two weeks after discovery of x-rays
Germany
Who was the first to take an intraoral radiograph?
What year?
Dr. C Edmond Kells, a New Orleans dentist
1896
Who was the inventor of the first dental x-ray unit?
Dr. William Rollins of Boston
Who developed an additional technique for exposing dental x-rays in 1920?
What was the technique called?
Frank McCormack
Paralleling technique
What is the paralleling technique also called?
Right angle technique
What year did Frank McCormack develop the paralleling technique?
1920
Who was credited with developing the 1st orthopantomograph unit that would take acceptable panoramic radiographs?
In what year?
Dr Y.V. Paatero
1959
Radiation is a type of ______________ energy
Electromagnetic
What are the most familiar forms of electromagnetic energy? (3)
Radio waves
Television waves
Visible light
True or false:
All electromagnetic energy have similar properties
True
What are the properties of electromagnetic energy? (3)
All energy travels in waves that move in straight lines at the speed of light
The waves consist of energy only. Energy can be sent through lines to a receiver
Electromagnetic energy is characterized by length of the wavelength
True or false:
Electromagnetic energy consists of mass
False, no mass is involved only energy
What are longer wavelength examples of electromagnetic energy?
Visible light, TV and radio waves
What are shorter wavelength examples of electromagnetic energy?
X-ray and gamma rays
Define ionization
Atoms charge into negatively of positively charged ions during radiation
Unless disturbed, electrons always remain ______ as they _____ the _______
Stable
Orbit
Nucleus
If disturbed, electrons are ____ and the atoms that have lost electrons become _________ ions. The positive ions can react with atoms in _______ and other ______
Lost
Positive
Tissues
Matter
Positive ions reacting with atoms in tissues and other matter can:
Alter living cells and tissues and even cause permanent damage
True or false:
Patient and operator must always be protected during exposure to ionizing radiation
True
What wavelengths are desired in dental radiographs?
Short wavelengths or hard radiations
Describe short wavelengths/hard radiations
High frequency
High energy
High penetrating
power
What radiation is unsuitable for exposing dental radiographs?
Soft radiation or long wavelengths
What are the 4 types of radiation?
Primary
Secondary
Scatter
Leakage
Describe primary radiation (3)
Central beam that comes from the x-ray tubehead
Consists of high energy, short wavelength x-rays travelling in a straight line
Useful x-ray that produces diagnostic image on the x-ray film
Describe secondary radiation
Forms when primary x-rays strike the patient or contact matter
What often happens to secondary radiation?
Longer wavelengths that lose their energy
Describe scatter radiation
Deflected from its path as it strikes matter, secondary and scatter radiation are used interchangeably
What type of radiation presents the most serious danger to the operator?
Why?
Scatter radiation
Scatter in all directions
Due to scatter radiation, the operator must stand at least _ feet from the patient while exposing x-ray film or ______ __________ _________ and out of the path of the _______ ____
6
Behind structural shielding
Primary beam
Describe leakage radiation
Escapes in all directions from the tube/tubehead
The x-ray machine must be checked for _______ and should ___ be used until problem is addressed
Leakage
NOT
True of false:
Leakage radiation is useful for the diagnostic process
False, long wavelengths only cause harm
What does one roentgen equal?
The amount of radiation that ionizes one cubic centimetre of air
What unit represents the amount of radiation that ionizes one cubic centimetre of air?
Roentgen (R)
What unit represents the amount of ionizing radiation absorbed in a substance?
Radiation absorbed dose (RAD) or Gray (GY)
What radiation absorbed dose (RAD) or Gray (GY) represent?
The amount of ionizing radiation absorbed in a substance
What unit represents the does at which body tissues are exposed, measure in terms of estimated biological effects in relation to an exposure does of one R of “x” or gamma radiation?
Roentgen equivalent man (REM) or Sievert (Sv)
What does one Roentgen equivalent man (REM) or Sievert (Sv) represent?
The dose at which body tissues are expose, estimated biological effects in relation to an exposure does of one R of “x” or gamma radiation
What is a milliroentgen (mr)?
One one-thousandth of an R
What is relative biological effectiveness (RBE)?
Measurement unit used to compare the biological effects on various tissues irradiated by different forms of energy
Dental X-Rays have arbitrarily been assigned an RBE unit of:
One
How is REM/Sv determined?
By multiplying the RAD by the RBE
True or false:
RAD and REM are considered equal for dental x-rays
True
_-____ can damage ____ _______; some injuries heal but some do ___
X-rays
Body tissues
Not
What may happen if a cell is affected by direct radiation? (4)
The cell may: Die immediately Change immediately Change at mitosis Remain unaffected
What cells do somatic group of cells include?
All cells except the reproductive cells
What cells do the genetic groups of cells include?
All the reproductive cells
Biological effects of radiation are classified according to ____ of ___ affected by the _________
Type
Cell
Radiation
Describe somatic effects of radiation
Can leave the individual in poor health and with cataracts, cancer or leukemia
Can somatic effects be passed on to the next generation?
No
Genetic effects may ___ _______ primary individual exposed to the radiation
Not involve
True or false:
The genetic effects can not be repaired and are passed to future generations
True
What are the most radiosensitive cells? (3)
Immature cells
Rapidly dividing cells
Cells that don’t perform specialized functions
_______ are very sensitive to radiation, therefore if _________ is suspected every precautions should be taken
Embryos
Pregnancy
What are cells that are less sensitive to radiation called?
Radioresistant
What cells are radioresistant?
Mature cells
What are radiosensitive tissues in the dental region? (2)
Lens of the eye
Thyroid gland
Individuals who routinely use ionizing radiation in their occupations are regulated by the dose limitations defined by who?
National Council on Radiation Protection and Measurements
What does MPD stand for? What does it mean?
Maximum Permissible Dose
Maximum dose of radiation that would not be expected to produce any significant radiation effects in a lifetime
What is the MPD?
0.05 Sv (5.0 rems) per year
Describe the control panel of the dental x-ray unit
Where the circuit boards and controls that allow the operator to adjust the correct setting for each patient are located
What determines the amount or quantity of electrons?
Milliamperage (mA)
What is milliamperage?
A measurement unit for electrical current
The higher the mA, the greater the amount of __________
Radiation
What is kilovoltage (kV)?
Determines the quality or penetrating power of the central beam
High the kV, the greater the ___________ power of the _-____ and the less _______ ____ required
Penetration
X-rays
Exposure time
Describe the electronic timer
Controls total time that rays flow from the x-ray tube
What is milliamperage seconds (mAs)?
Determine the amount of radiation exposure the patient receives
What is mA?
Milliamperage
What is kV?
Kilovoltage
What is mAs?
Milliamperage seconds
To determine mAs, what do you do?
Calculate the milliamperage times the exposure time
Define contrast in dental x-ray unit
The difference between the shades of x-ray
What do the black, white and shades of grey on an x-ray film determine?
The densities of the subject and the film
What is contrast in dental x-rays controlled by? (4)
kV
Developing process
Film fog
Distortion
What is density in dental x-rays?
The degree of darkness on an x-ray
Contrast is the difference between __________ of adjacent areas on a film
Densities
The arm assembly attached firmly to the ____ in the x-ray room
Wall
What allows the operator to freely position the tube head?
Flexible extension
What is the tubehead?
Where x-ray vacuum tube and step-up and step-down transformers are located
What is the x-ray tube also known as?
Coolidge tube
What is the dimensions of the x-ray tube?
Approximately 6 inches long and 1.5 inches in diameter
On _______ side of tube; a ________ ___ is positioned
Cathode
Focusing cup
Where do electrons originate in the x-ray?
Focusing cup
What is the focal spot?
A small spot on the tungsten target where the electrons hit
What is the hard x-rays with short wavelengths?
Central beam
What is the collimator?
Lead disc with an opening in the middle that restructures the beam and filters out additional weak rays
Who’s responsibility is it to follow safety and precaution measures when using radiography equipment? (3)
Manufacturers
Dental team members
Patients
Machine must have ________ control switch to ___ ___ electricity to the machine
Separate
Cut off
What is the purpose of the deadman switch?
Ensures that exposure ends when the preset time has passed and not when button is released
What does PID stand for?
Position Indicating Device
The PID must be ____ _____ and x-ray tube must be sealed in an ___-________ ______
Lead lines
Oil-immersed casing
The control panel must have indicators that display:
mA
kV
Impulsed per exposure time
What is the collimator made of?
Lead plate
What is required and built into the head of all x-ray machines?
Filtration of 2.5mm of aluminum
