CH3: EM Radiation and Particulate Radiation Flashcards
How is all EM Radiation is similar?
no mass
carries energy in waves of electric and magnetic disturbances through space
travels at speed of light
EM spectrum varies in…
energy, wavelength, frequency
all energy on the EM spectrum have the same…
velocity or speed
What is the speed of light?
3 x 10^8 m/s
What occurs to cause EM radiation to be emitted?
radioactive decay - atom with excess energy in it’s nucleus emits particles and energy to regain stability
Define a half-life
the time it takes for half the atoms of an element to decay
How long does radioactive decay take?
depends, may happen in seconds or billions of years
Describe particulate radiation
able to ionize atoms (alpha and beta)
Equation to calculate EM energy
E = hf
E – energy measured in eV
h – 4.135 x 10^-15 (Plank’s constant)
f = frequency of photon, measured in Hertz
Plank’s Constant, what is it and how is it used
used to calculate photon energies based on frequency
4.135 x 10^(-15)
EM radiation may exhibit properties of waves of particles. This is referred to as…
List three (3) characteristics exhibited by X rays and gamma rays that are also properties of a particle?
can burn the skin
intensity varies according to inverse square law
able to ionize matter
There are five types of non-ionizing EM radiation. List them from low to high. Briefly describe each
radiowaves - radio stations and MRI
Microwaves - cell phones, heating food
Infrared light - signal between remote and TV
Visible light - colors visible to the human eye
Ultraviolet light - higher energies, tanning beds
What are the two radiation types on the EM spectrum that are ionizing? How are they used in healthcare?
X-rays - medical imaging
Gamma Rays - nuclear medicine
Write the formula for calculating wavelength or frequency.
Velocity = frequency x wavelength
A high frequency sine wave would have _____ (long, short) wavelength
short
A sine wave with long wavelength would have ___ (high, low) energy
low
From one crest a wave to the next crest of a wave is called….
wavelength
The height of a wave is called the _____
amplitude
How would you describe a photon?
massless package of energy
no mass or charge
speed of light
define wave frequency
number of wave cycles per second
What is responsible for determining the differences in energy of EM radiation?
wavelength and frequency
If an xray beam is polyenergetic, what does that mean?
has various energy levels
a majority of photons in the xray beam are created through what process
Bremsstrahlung radiation
What is the average energy of the xray beam called?
beam quality
What term describes a beam that diverges equally in all directions?
isotropic
What are three reasons to know about EM radiation in xray?
1) be able to answer patient questions and assure them of safety
2) to be knowledgeable of the equipment and radiation you use every day
3) dispel misconceptions or myths about x-rays
Who is James Maxwell?
define velocity in EM radiation
speed of light
What uses more energy - higher frequency (short wavelength) or lower frequency (long wavelength)
Higher frequency/short wavelength
_____ (high/low) frequency is associated with higher KVP
high
A ____ (high/low) frequency wave has more penetrating power in xray.
high
What is the overall concept of the inverse square law?
as you move closer to the source, the intensity will increase and vice versa
Inverse Square Law Formula
(Intensity 1 / Intensity 2) = (Distance 2^2 / Distance 1^2)
intensity diminishes by a factor of the square of the distance as you move away from the source
Differentiate between gamma and xrays
Gamma - originates in the nuclei of atoms when giving off excess energy
X-ray - originates through interaction between atoms and electrons (Brems, Characteristic, Compton, photoelectric)
Describe Alpha particles
two protons bound to two neutrons with a net positive charge
LARGE - cannot penetrate most things, cannot travel far
Quickly pick up electrons b/c of positive charge
Describe beta particles
an electron emitted from an unstable nucleus
smaller, lighter
can penetrate light materials
longer range and can ionize atoms in its path
positive or negative
