Ch. 4 Image Production Flashcards
What is matter?
Matter has form or shape and occupies space
Matter is anything that has mass and volume.
What is mass?
Mass is the amount of matter in an object; generally considered the same as weight
Mass is a measure of the quantity of matter, while weight is the force exerted by gravity on that mass.
What is energy?
Energy is the ability to do work
Energy exists in various forms and can be transformed from one form to another.
What is potential energy?
Potential energy is the energy of position
It is stored energy that has the potential to do work due to an object’s position.
What is kinetic energy?
Kinetic energy is the energy of motion
An object in motion has kinetic energy, which depends on its mass and velocity.
What is electrical energy?
Electrical energy is the energy resulting from the movement of electrons
It is a form of energy that can be harnessed for various applications.
What is electromagnetic energy?
Electromagnetic energy is energy that is emitted and transferred through matter
It includes a range of energies such as radio waves, visible light, and X-rays.
What is ionizing radiation?
Ionizing radiation is electromagnetic radiation that is able to remove an electron from an atom
This type of radiation can cause damage to biological tissues and is used in medical imaging and treatments.
What is ionization?
Ionization is the removal of an electron from an atom
This process can create charged particles known as ions.
What is the SI unit for length?
meter
What is the SI unit for mass?
kilogram
What is the SI unit for time?
second
What are the base units of the SI system?
meter, kilogram, second
Define work in physics.
force applied on an object over a distance
What is power in terms of work?
rate of doing work (measured in watts)
What does the atomic nucleus contain?
Protons and neutrons
What is the atomic mass number represented by?
The letter A
What do electron shells contain?
Orbital electrons
In a stable atom, what is equal?
The number of electrons and protons
What does the atomic number represent?
The number of protons in the nucleus
What letter represents the atomic number?
Z
What determines the chemical element?
The atomic number
What are isotopes?
Atoms with the same number of protons but different number of neutrons
What is electron-binding energy?
The force that holds electrons in orbit around the nucleus
What are alpha particles?
Helium nucleus—two protons and two neutrons
What are beta particles?
Electron-like particles emitted from the nucleus of a radioactive atom
What is the octet rule?
The outer shell of an atom may not contain more than 8 electrons
What is a photon?
Smallest amount of any type of electromagnetic radiation
What do sine waves represent?
Waves of electromagnetic radiation
What is amplitude?
Wave height in electromagnetic radiation
What is wavelength?
Distance between the peaks of waves
As photon wavelength decreases, what happens to photon energy?
Photon energy increases
What is frequency?
Number of wavelengths passing a given point per unit time
How is frequency measured?
In hertz (Hz)
What is the speed of electromagnetic radiation?
3 x 10^8 meters per second
What are gamma rays?
Electromagnetic rays produced in the nucleus of radioactive atoms
What is wave-particle duality?
Concept that x-ray photons exist as waves and exhibit properties of particles
What is attenuation?
Partial absorption of the energy of an x-ray beam
What does the inverse square law state?
Intensity of the x-ray beam is inversely proportional to the square of the distance
What is the law of conservation of matter?
Matter cannot be created or destroyed, only changed in form
What is the law of conservation of energy?
Energy cannot be created or destroyed, only changed in form
What are electrostatics?
Stationary electrical charges (static electricity)
What is electrification?
Movement of electrons between objects
What do the laws of electrostatics state?
Unlike charges attract, and like charges repel
What are the methods of electrification?
Friction, contact, and induction
What is a conductor?
Material that allows the free flow of electrons
What is an insulator?
Object that prohibits the flow of electrons
What is electrical current?
Movement of electrons along a conductor or pathway
How is electrical current measured?
In amperes
What is electromotive force (EMF)?
The force with which electrons move in an electrical circuit
How is EMF measured?
In volts
What is a semiconductor?
Material that may act as an insulator or conductor under different conditions
What is an electrical circuit?
Path along which electrons flow
What is alternating current (AC)?
Electrical circuit in which current oscillates back and forth
What is direct current (DC)?
Unidirectional flow of electrons in an electrical conductor
What does a sine wave represent?
Electron flow as alternating current
What is a magnetic field?
Energy field surrounding an electrical charge in motion
What is electromagnetism?
Movement of electrons in a conductor produces a magnetic field
What is electromagnetic induction?
Causing an electrical current to flow in a conductor when placed within a magnetic field
What is self-induction?
Opposing voltage created in a conductor by passing alternating current through it
What is mutual induction?
Inducing current flow in a secondary coil by varying the current flow through a primary coil
What is an electrical generator?
Device that converts mechanical energy to electrical energy
What is single-phase, two-pulse alternating current?
Simplest type of current; voltage flows as a sine wave
What is three-phase alternating current?
Wiring patterns used to create voltage waveforms 120 degrees out of phase
What does a step-up transformer do?
Increases voltage from primary to secondary coil
What does a step-down transformer do?
Decreases voltage from primary to secondary coil
What is an autotransformer?
Transformer with a single winding of wire used for small voltage increases
What is rectification?
Process of changing alternating current to direct current
What is line voltage compensation?
Keeps incoming voltage adjusted to proper value in x-ray circuit
What are the conditions necessary for the production of X-rays?
- Source of electrons
- Acceleration of electrons
- Sudden stoppage of electrons against target material
What is an autotransformer also known as?
Variable transformer
What is the primary function of an autotransformer in the x-ray circuit?
Provides for the variation of voltage flowing in the x-ray circuit and applied to the x-ray tube
How does an autotransformer operate?
Operates on the principle of self-induction
What voltage is fed to the primary turns of the autotransformer?
220 V
What does the prereading voltmeter indicate?
The voltage that is selected
What is the purpose of a timer in the x-ray circuit?
Regulate the duration of x-ray exposure
What is an mAs timer used for?
Provides the safest tube current in the shortest time possible
What is an electronic timer in radiographic equipment?
Microprocessor controlled and allows exposure times of 1 ms (0.001 second)
What does automatic exposure control (AEC) rely on?
Excellent positioning skills and extensive knowledge of surface and internal anatomy
Fill in the blank: The minimum response time with an AEC is _______.
1 ms (0.001 second)
What is a falling load generator?
A modern generator that takes advantage of extremely short time capabilities and tube heat-loading potential
What is the principle of operation for a step-up transformer?
Operates on the principle of mutual induction
True or False: A step-up transformer requires direct current (DC) to operate.
False
What is the turns ratio in a step-up transformer?
The number of turns of the wire in the primary coil compared with the number of turns in the secondary coil
What does a rectifier do in the x-ray circuit?
Changes AC coming from the step-up transformer to DC
What type of diodes do full-wave rectifiers use?
Solid-state semiconductor diodes
What is the voltage ripple for three-phase, 12-pulse equipment?
Approximately 4%
What does a milliammeter (mA meter) measure?
Tube current in milliamperes
What does mA control regulate?
The number of electrons available at the filament to produce x-rays
What materials are used for filaments in the x-ray tube?
Tungsten with a small amount of thorium
What is thermionic emission?
The process where electrons are boiled off the filament during x-ray exposure
What is the purpose of the focusing cup in the cathode assembly?
Concentrate electrons boiling off the filaments into a narrower stream
What is the target material in the anode of an x-ray tube?
Tungsten–rhenium alloy
What is the line-focus principle?
Larger actual focal spot provides greater heat capacity while smaller effective focal spot increases image sharpness
What is the tube window?
Thinner section of glass envelope that allows x-rays to escape
What is the function of tube housing?
Supports and protects the tube, restricts leakage radiation, and provides electrical insulation
