RADT 334 - UNIT 2

photon

The smallest quantity of any type of electromagnetic radiation; it may be pictured as a small bundle of energy, sometimes called a quantum.

radiolucency

Characteristic of materials that allow x-rays to penetrate with a minimum of attenuation. Radiolucent structures are nearly invisible on radiographs.

the inverse square law

A mathematical relationship describing the reduction in radiation intensity with distance from a point source. The intensity is inversely proportional to the square of the distance of the object to the source.

frequency

The number of wavelengths passing a point per second

the law of conservation of energy

Energy can be transformed into another form or into matter, but it cannot be created or destroyed.

gamma ray

A form of ionizing electromagnetic radiation emitted from the nucleus of a radioactive atom

electromagnetic spectrum

The wide range of electromagnetic radiation described by its frequency, wavelength or energy

sinusoidal variation

The mathematical or graphical description of a simple harmonic motion

quantum

A single unit of electromagnetic radiation

visible light

A narrow region in the middle of the electromagnetic spectrum extending from approximately 400 nm (blue) to 700 nm (red)

400 m/s

A thunder clap associated with lightning has a frequency of 800 Hz. If its wavelength is 50 cm, what is its velocity?

1.25 mR/mAs

The output intensity of a normal radiographic imaging system is 5mR/mAs at 100 cm. What is the output intensity of such a system at 200 cm?

Velocity = frequency × wavelength

What is the wave equation?

inversely

How are frequency and wavelength related?

radiofrequency, visible light, and x-radiation

What are the three imaging windows of the electromagnetic spectrum?

Hertz

What unit of measure is used for radiofrequency?

meters

What unit of measure is used for visible light?

electron volts

What unit of measure is used for x-radiation?

30-150 keV

What is the energy range of diagnostic x-rays?

origin

What is the difference between x-rays and gamma rays?

wave-particle duality

Some regions in the EMS behave like waves and some regions behave like particles in their interaction with matter. What is this phenomenon called?

attenuation

The reduction of x-ray beam intensity because of absorption and scatter is called this.

coloumb

Unit of electric charge

electrodynamics

electric charges in motion

electric power

electric current (A) through a potential (V)

electrostatics

stationary electric charges

dipole

two poles

induction

The ability to transfer energy from one object to another without touching

magnetic domain

An accumulation of many atomic magnets with their dipoles aligned

autotransformer

An iron core transformer with only one winding

Gauss and Tesla

units of magnetic intensity

electric potential

The energy that causes electrons to move in a conductor; measured in volts (V)

50 ohms

What is the total circuit resistance when resistive elements of 5, 10, 15, and 20 ohms are connected in a series circuit?

2.4 ohms

What is the total circuit resistance when resistive elements of 5, 10, 15, and 20 ohms are connected in a parallel circuit?

Closed-core, autotransformer, and shell-type

Name three types of transformers

Contact, friction, induction

Name three ways to electrify an object

Four laws of electrostatics

The following are all parts of what?

1) Unlike charges attract; like charges repel;

2) Coulomb's Law of electrostatic force;

3) Electrostatic force follows the inverse square law;

4) electric charges are uniformly distributed except at regions of high curvature where they concentrate.

Humidity allows excess electrons to attach to water molecules in the air

Why is electrification easier in dry Phoenix than in humid Houston?

1000:1

A mobile x-ray imaging system operates on 110 V AC power. Its maximum capacity is 110 kVp and 100 mA. What is the turns ratio of the high-voltage transformer?

The high voltage generators in x-ray imaging systems are magnetic devices. Magnetic resonance imaging deals with static and varying magnetic fields.

What is the role of magnetism in the study of x-ray imaging?

Permanent magnets; electromagnets; superconducting magnets

List three prinicple types of magnets

Electromagnet

Current-carrying coil wrapped around a ferromagnetic core

Voltage is equal to the product of current and resistance.

State Ohm's law

It loses its magnetic properties

What happens when a bar magnet is heated to a very high temperature?

wood and glass

Examples of nonmagnetic material

water and plastic

Examples of diamagnetic material