Dental Radiology Exam 1
_____ scatter involves an x-ray photon that has its path altered by matter. It accounts for 8% of the scatter from the x-ray beam.
Coherent- no change in the atom
_____ scatter accounts for 62% of the scatter that occurs in diagnostic radiography.
Compton
_____ refers to how sharply dark and light areas are differentiated or separated on an image. An adjustment in kilovoltage results in a change to this.
Contrast
The _____ functions to dissipate the heat away from the tungsten target.
Copper stem
The heat produced during the production of x-rays is carried away from the ____ ____ and absorbed by the ____ ____ in the tubehead.
Copper stem Insulating oil
_____ is the overall darkness or blackness of an image. An adjustment in kilovoltage results in a change in this
Density
Wavelength can be defined as the _______ between the crest of one wave and the crest of the next.
Distance
____ -____ ____be used to correlate the "response," or damage, of tissues with the "dose," or amount, of radiation received
Dose-response curve
Who exposed the first dental radiograph in the US using a live person?
Edmund Kells
________ radiation can be defined as the propagation of wavelike energy (without mass) through space or matter
Electromagnetic
Cosmic rays, gamma rays, x-rays, ultra- violet rays, visible light, infrared light, radar waves, microwaves, and radio waves are all types of what kind of radiation?
Electromagnetic radiation (only high-energy radiations like cosmic rays, gamma rays, and x-rays are capable of ionization)
_____ effects (aka deterministic effects), increase in severity as does increases, has a threshold, and occur due to major cell damage or cell death. Ex) Erythema, decrease in fertility
Nonstochastic
A ________ dose- response curve suggests that no matter how small the amount of radiation received, some biologic damage does occur
Nonthreshold
Who made the first dental radiograph?
Otto Walkhoff
Lastly, the size of the x-ray beam is restricted by the ____ ____. The x-ray beam then travels down the lead-lined ___ and exits the tubehead at the opening.
PID
What part of the x-ray machine aims and shapes the x-ray beam?
PID (Position-Indicating Device)
What type of radiation contains tiny particles of matter that possess mass and travel in straight lines and at high speeds? This type of radiation also produces kinetic energy by means of their extremely fast-moving, small masses.
Particulate Radiation *There are four types*
Ionizing radiation can be classified into 2 groups. What are they?
Particulate and Electromagnetic Radiation
Following the latent period is the ______ ______ ______.
Period of injury
The particle concept characterizes electromagnetic radiations as discrete bundles of energy called ________.
Photons
1 rad = ____ Gy 1 Gy = ____ rad
0.01 100
Less than ____% of the energy is converted to x-rays and the remaining ___% is lost as heat.
1% 99%
When x-ray photons arrive at the patient with energies produced by the dental x-ray machine, one of the following events may occur:
1) X-rays can pass through the patient without any interaction 2) X-ray photons can be completely absorbed by the patient 3) X-ray photons can be scattered
The filament circuit uses the 3-5 V to heat the ____ ____ in the cathode. ____ ____ occurs during this step, which is defined as the release of electrons from the tungsten filament when the electrical current passes through it and heats the filament.
1)Filament circuit 2)Thermionic Emission
One milliampere (mA) is equal to __/____ of an ampere
1/1000
Characteristic radiation accounts for a very small part of x-rays produced in the dental x-ray machine. It occurs only at or above ___kV.
70
Current fast radiographic film requires ___% less exposure time than the initial exposure times used in 1920.
98%
The distance from the source of radiation (tungsten target in anode) to the receptor
Target-receptor distance
____ refers to the total transfer of energy from the x-ray photon to the atoms of matter through which the x-ray beam passes.
Absorption
What type of radiation effects take place over a short period of time and produce short term effects. This type tends to kill cells, and can damage organs and tissues. Ex) Immediate responders to nuclear disaster effects
Acute (high dose) Effects: skin burns, hair loss, sterility, cataract
This type of particulate radiation is emitted from the nuclei of heavy metals and exist as two protons and neutrons, without electrons
Alpha particles
Sheets of 0.5-mm-thick aluminum placed in the path of the x-ray beam, filter out the non-penetrating, longer wavelength x-rays
Aluminum discs
____ is the measurement of the number of electrons moving through a conductor.
Amperage- measured in amperes (A) or milliamperes (mA)
The unit of measure used to describe the number of electrons, or current flowing through the cathode filament
Ampere (A)
This type of particulate radiation are fast-moving electrons emitted from the nucleus of radioactive atoms
Beta Particles
The _______, or negative electrode, consists of a tungsten wire filament in a cup-shaped holder made of molybdenum
Cathode
What type of particulate radiation are streams of high-speed electrons that originate in an x-ray tube?
Cathode rays
When the exposure button is pressed, the high-voltage circuit is activated and the electrons produced at the ____ are accelerated across the x-ray tube to the ____.
Cathode to the anode
_____ radiation is produced when a high-speed electron dislodges an inner-shell electron from the tungsten atom and causes ionization of that atom
Characteristic
What type of radiation effects take place over a long period of time and produce long term effects? The results can be observed for years and can have genetic and somatic effects. Ex) skin cancer from sun exposure
Chronic (low dose)
The distance from the source of radiation (tungsten target in anode) to the patient's skin
Target-surface distance
Who modified that paralleling technique with the introduction of the long-cone technique?
F. Gordon Fitzgerald
After the electricity enters into the x-ray machine from the wall outlet, the current is directed to the _____ _____ and step down transformed where the 110 or 220 entering-line voltage is reduced to ___ to ___ V.
Filament circuit 3 to 5
An uncharged (neutral) atom or molecule that exists with a single, unpaired electron in its outermost shell
Free radical
________ refers to the number of wavelengths that pass a given point in a certain amount of time. It is also inversely related to wavelength.
Frequency
Speeding electrons slow down because of their interactions with the tungsten target in the anode. Many electrons that interact with the tungsten atoms undergo not one but many interactions within the target. The radiation produced in this manner is known as ____ radiation, or ____ radiation (brems- strahlung). Happens 70 % of the time.
General or braking (The term braking refers to the sudden stopping of high-speed electrons when they hit the tungsten target in the anode.)
The reproductive cells (e.g., ova, sperm) are termed ______ cells.
Genetic
_____ effects are not seen in the irradiated person but are passed on to future generations
Genetic
When placed in the path of the x-ray beam, the thickness of a specialized material (e.g., aluminum) that reduces the intensity by half is termed the
Half-value layer (HVL)
When low kilovoltage is used, a ____-contrast image will result.
High
_____ is a term of measurement that refers to the fact that x-rays are created in a series of bursts or pulses rather than in a continuous stream.
Impulse
What is an advantage of digital imaging?
Increased speed of viewing images
What surrounds the x-ray tube and transformers inside the tubehead to prevent overheating by absorbing the heat created by the production of x-rays?
Insulating oil
The intensity of radiation is inversely proportional to the square of the distance from the source of radiation.
Inverse Square Law
The production of ions, or the process of converting an atom into ions is _______.
Ionization
_______ is produced through the photoelectric effect or Compton scatter and results in the formation of a positive atom and a dislodged negative electron
Ionization
Absorption occurs as a result of the photoelectric effect which is a form of ____ radiation. It accounts for ___% of the interactions of the dental x-ray beam with matter.
Ionizing 30%
What do you call radiation that is capable of producing ions by removing or adding an electron to an atom?
Ionizing Raditation
The _____ period can be defined as the time that elapses between exposure to ionizing radiation and the appearance of observable clinical signs
Latent period
What part of the x-ray machine restricts the size and shape of the beam?
Lead collimator
The ____ is a leaded-glass vacuum tube that prevents x-rays from escaping in all directions.
Lead glass housing One central area of the leaded-glass tube has a "window" that permits the x-ray beam to exit the tube and directs the x-ray beam toward the aluminum disks, lead collimator, and PID.
Your patient asked you why dental images are important. You explain:
Many dental diseases are typically discovered only through the use of dental images
_________ controls the penetrating power of the x-ray beam by controlling the number of electrons produced in the x-ray tube and the number of x-rays produced.
Milliamperage
Next, the ____ ____ in the cathode directs the electrons to the tungsten target in the anode.
Molybdenum cup
What part of the x-ray machine focuses the electrons into a narrow beam and directs the beam across the tube toward the tungsten target of the anode?
Molybdenum cup
____ radiation refers to the penetrating x-ray beam that is produced at the target of the anode and that exits the tubehead.
Primary- the x-ray beam is often referred to as the primary or useful beam
The ____ is the mean energy or penetrating ability of the x-ray beam.
Quality - controlled by kilovoltage
The ____ of the x-ray beam refers to the number of x-rays produced in the dental x-ray unit
Quantity
The emission and propagation of energy through space or a substance in the form of waves or particles is _____.
Radiation
What is the process by which certain unstable atoms or elements undergo spontaneous disintegration, or decay, in an effort to attain a more balanced nuclear state?
Radioactivity
An image or picture produced on a receptor (radiation-sensitive film, phosphor plate, or digital sensor) by exposure to ionizing radiation; a two-dimensional representation of a three-dimensional object
Radiograph
The art and science of making radiographs by the exposure of film to x-rays
Radiography
The science or study of radiation as used in medicine; a branch of medical science that deals with the therapeutic use of x-rays, radioactive substances, and other forms of radiant energy.
Radiology
The last event in the sequence of radiation injury is the _______ period
Recovery
____ radiation is a form of secondary radiation and is the result of an x-ray that has been deflected from its path by the interaction with matter.
Scatter - deflected in all directions by patient's tissues and travels to all parts of the body and dental operatory
____ radiation refers to x-radiation that is created when the primary beam interacts with matter. It is also less penetrating than primary radiation.
Secondary
____ effects are seen in a person who has been irradiated.
Somatic
______ are all the cells in the body except the reproductive cells.
Somatic
The _____(3 words) is used to decrease the voltage from the incoming 110- or 220-line voltage to the 3 to 5 V used by the filament circuit.
Step-down transformer
The _____ (3 words) is used to increase the voltage from the incoming 110- or 220-line voltage to the 65,000 to 100,000 volts used by the high-voltage circuit.
Step-up transformer
_____ effects occur as a direct function of dose, have no does threshold, and occur due to ionization effects on chromosomes (mutation). Ex) Cancer, genetic
Stochastic
The distance from the source of radiation (tungsten target in anode) to the tooth
Target-object distance
What part of the x-ray machine produces electrons when heated? Where is it located?
The tungsten filament located in the cathode
What part of the x-ray machine alters the voltage of incoming electricity?
Transformer
True or False: Only high-energy radiations like cosmic rays, gamma rays, and x-rays are capable of ionization
True
This part of the x-ray machine is a tightly sealed, heavy metal housing that contains the x-ray tube that produces dental x-rays.
Tubehead
A plate of tungsten, which serves as a focal spot and converts bombarding electrons into x-ray photons.
Tungsten plate
Next, the x-rays travel through the ____ ____ ____, the tubehead seal, and the aluminum disks.
Unleaded glass window
_____ refers to the speed of the electromagnetic wave.
Velocity
____ is the measurement of electrical force that causes electrons to move from a negative pole to a positive one.
Voltage- measured in volts (V) or kilovolts (kV)
What is the first step in the production of x-rays?
When electricity enters the x-ray machine through the wall outlet
The x-ray was discovered by _____ ____.
Willhelm Roentgen
Who developed the first dental x-ray unit?
William H. Rollins
A high-energy radiation produced by the collision of a beam of electrons with a metal target in an x-ray tube
X-Radiation
A beam of energy that has the power to penetrate substances and record image shadows on receptors (photographic film or digital sensors).
X-Ray
_____ can be defined as weightless bundles of energy (photons) without an electrical charge that travel in waves with a specific frequency at the speed of light.
X-Rays
The____, or positive electrode, consists of a wafer-thin tungsten plate embedded in a solid copper rod. The purpose of the anode is to convert electrons into x-ray _____.
anode photons
Wavelength determines the energy and penetrating power of the radiation. The shorter the wavelength, the ______ the energy and penetrating power.
higher
The ____ is the traditional unit of dose.
rad (radiation absorbed dose)
What electron shell has the highest energy?
the K shell is located closest to the nucleus and has the highest energy level