PHOTONS Bushong, Chapter 4

PHOTONS Smallest quantity of electromagnetic energy Bundle of energy AKA Quantum No Mass- electric/magnetic fields- sine waves Travel at speed of light Energy disturbances interact with matter Exists over wide energy range

James Clerk Maxwell discovered light and x-rays have electric and magnetic properties. Sine Wave Model used to help describe the properties of photons.

Amplitude-

Frequency-

Wavelength-

C=fXLambda

Relationships Between These Terms Velocity (C or V) Decreases Increases Frequency (F) wavelength (Lambda)

Electromagnetic Energy Frequency Wavelength Energy What does this relationship tell us about imaging systems?( let’s look at following slide)

Match the Units of measurement HZ Meter Volts Energy Frequency Wavelength

Ionizing Radiation Ionizing means that the radiation is able to cause changes in the structure of an atom. 80 kVp produces x-rays in the 0-80 keV range X-rays are artifically produced in an x-ray tube electron cloud Gamma rays come from inside the nucleus of a radioactive atom

Wave and Particle Theories Visible light identified by wavelength RF identified by frequency X-rays are identified by energy Visible light acts like wave X-rays act like particles

Size of the object VS size of wave (water compared to photons)

Energy attenuation and reduction in intensity from scatter and absorption.

Energy is reflected when waves crash into a bulkhead Energy is reflected when waves crash into a bulkhead. It is absorbed by a beach. It is partially absorbed or attenuated by a line of pilings. Light is also reflected, absorbed, or attenuated, depending on the composition of the surface on which it is incident.

Radiolucent VS Radiopaque

Definitions ENERGY Reflection Transmission Absorption LIGHT Transparent Translucent Opaque Important in Radiology Attenuation Radiopaque Radiolucent

Inverse Square Law Intensity VS Distance