Bushong Chapter 4 Electromagnetic Energy

Electromagnetic energy

Type of energy in X-rays, radio waves (radio frequencies), microwaves, and visible light

Quantum

An xray photon

Amplitude

One half the range from crest to valley over which the sine wave varies

Sine wave

Variation in the movement of protons in electrical and magnetic fields

Frequency

• the number of wavelengths that pass a point of observation per second

• Expressed in hertz

• 1 Hz= 1 cycle per second

Wavelength

• distance between similar points on a sine wave; the length of one cycle

• Designated with the lambda symbol

Electromagnetic spectrum

• continuum of electromagnetic energy

• Good X-rays Use Violent Idiots Making Roentgens

Refraction

Deviation of course that occurs when photons of visible light traveling in straight lines pass from one transparent medium to another

Radiofrequency (RF)

• electromagnetic radiation with frequencies from 0.3 Hz to 300 Hz

• MR uses RF in range of 1-100 Hz

Microwave

Short wavelength radiofrequency

Visible light

• radiant energy in the electromagnetic spectrum that is visible to the human eye

• Identified by wavelength

Wave particle duality

Principle that states that both wave and particle concepts must be retained, because wave like particles are exhibited in some experiments and particle like properties are exhibited in others

Reflection

Return of re-entry of an xray

Transmission

Passage of an xray beam through an anatomic part with no interaction with anatomic structures

Absorption

• transfer of energy from an electromagnetic field to matter

• Example: removal of X-rays from a beam via the PE effect

Attenuation

Reduction in radiation intensity that results from absorption and scattering

Inverse square law

• the intensity of radiation at a location is inversely proportional to the square of the distance from the source of radiation

Planck’s quantum theory

• denotes a relationship between energy and frequency

• States photon energy is directly proportional to photon frequency

• E=hf

Law of conservation of matter

Principle that states that matter can be neither created nor destroyed

Law of conservation of energy

Energy cannot be created nor destroyed

Photon

• quantum of electromagnetic energy

• Had neither mass nor electric charge

• Interacts with matter as though it is a particle

• Example: X-rays, gamma rays

• Travel at speed of light

• 186,000 miles/ second

• 3×10^8 meters per second

• 3×10^10 cm/second

Continuum

An uninterrupted ordered sequence