RADT 1002 Chapter 3
opaque material
completely absorb the light source.
Sine Wave Model
describes variations in the electric and magnetic fields as the photon travels with velocity
properties of sine wave model
frequency and wave length[Greek letter lambda (λ)].
valley
lowest point of a wave form
field
used to describe interactions among different energies, forces, or masses that can only be described mathematically
General characteristic of waves
velocity, amplitude, frequency, and wavelength.
three regions of electromagnetic spectrum
visible light, radiofrequency, and x- and gamma radiation
transparent material
will allow light to transmit through unaltered
Electromagnetic radiation varies in terms of its:(1) Wavelength(2) Frequency(3) Velocity (speed)
1 and 2 only Electromagnetic energies can be described in four general characteristics of waves: velocity, amplitude, frequency, and wavelength. Whereas the amplitude, frequency, and wavelength of electromagnetic energies can change, the speed (velocity) for electromagnetic energy remains the same for all forms of electromagnetic energies: the speed of light (186,282 miles per second, or 3 x 108 m/s)
Light interacts with matter in which of the following ways?(1) Attenuation(2) Transmission(3) Absorption
1, 2, and 3 Light interacts with matter in three particular ways. Transmission, absorption, and attenuation describe how light can interact with different materials. A transparent material will allow light to transmit through unaltered, while translucent materials can scatter light, attenuating or reducing its intensity level. Opaque materials will completely absorb the light source.
speed of light
186,282 miles per second, or 3 x 108 m/s
What is the intensity of light at 12 meters if the light's intensity was 100 millilumens (mlm) at 6 meters?
25 mlm As described by the inverse square law, intensity is inversely proportional to the square of the distance of the object from the source. In this example, the distance was doubled, therefore the intensity was reduced by 4.
Which wave characteristic refers to the height of a wave?
Amplitude The amplitude refers to the height of a wave. Amplitude is the maximum height of the wave measured from its average height. A wave with large amplitude is generally stronger than a wave with smaller amplitude
quantum
An x-ray photon
Which of the following is not a member of the electromagnetic spectrum?
Beta rays The electromagnetic spectrum is a grouping of radiate energies ranging from frequency ranges of 102 to 1024 Hz. The photons of these various portions of the electromagnetic spectrum differ only in frequency and wavelength. The known electromagnetic spectrum has three regions most important to radiologic science: visible light, radiofrequency, and x- and gamma radiation.
electromagnetic spectrum
Continuum of electromagnetic energy a grouping of radiate energies ranging from frequency ranges of 102 to 1024 Hz.
refraction
Deviation of course that occurs when photons of visible light traveling in straight lines pass from one transparent medium to another
wavelength
Distance between similar points on a sine wave; the length of one cycle the distance from one crest to another, from one valley to another, or from any point on the sine wave to the next corresponding point. Wavelength is generally expressed in meters (m).
photon
Electromagnetic radiation that has neither mass nor electric charge but interacts with matter as though it is a particle; x-rays and gamma rays smallest quantity of any type of electromagnetic energy has no mass or form
Planck's quantum theory stated all of the following points except:
Energy can be destroyed and created. Max Planck, a German physicist, discovered that one photon at a frequency twice that of a second photon also has twice the energy as expressed by his quantum theory. It expressed that x-rays are created with the speed of light, exist with velocity, or do not exist at all. It also stated that a photon's energy is directly proportional to its frequency and mathematically represented that relationship with Planck's constant
The laws of conservation state that matter and energy are easily created, conserved, and destroyed.
False Einstein's theory of relativity elaborated the laws of conservation that stated that energy and mass are equivalent and neither could be created nor destroyed but simply transformed
wave equation
Formula that states that velocity equals frequency multiplied by wavelength the longer the wavelength, then the lower the frequency, or the shorter the wavelength, then the higher the frequency
Which term accounts for the number of waves that pass a set point in a set amount of time?
Frequency Frequency refers to the number of waves that go by a specific point in one second. One could observe the frequency of a waveform by fixing attention on one point and watching the rises—crest—and falls—valley—of the wave harmonically as it passes the point of observation. This rate of rise and fall is the wave's frequency. It is calculated as the number of cycles per second and measured in the unit hertz (Hz)
Planck's constant (h)
Fundamental physical constant that relates the energy of radiation to its frequency
wave-particle duality
In some experiments, light behaves as if it is composed of waves (electromagnetic waves), and in other experiments, light behaves as if it is composed of tiny particles, called photons. The current interpretation of these observations is that light and matter both have some properties in common with waves and with particles.
transmission
Passage of an x-ray beam through an anatomical part with no interaction with atomic structures
visible light
Radiant energy in the electromagnetic spectrum that is visible to the human eye
radiolucent
Referring to a tissue or material that transmits x-rays and appears dark on a radiograph
reflection
Return or reentry of an x-ray
sinusoidal
Simple motion; a sine wave
What is the velocity of electromagnetic radiation?
Speed of light The speed (velocity) for electromagnetic energy is the same for all forms of electromagnetic energies: the speed of light (186,282 miles per second, or 3 x 108 m/s)
quantum theory
Theory in the physics of matter smaller than an atom and of electromagnetic radiation X-rays are created with the speed of light (c), and they exist with velocity (c) or they do not exist at all. Photon energy is directly proportional to photon frequency. The relationship is expressed in Planck's quantum equation as E = hf. E represents the photon energy, while f represents the photon frequency. The other variable is a constant illustrating the proportionality of energy to frequency, known as Planck's constant (h) , with a numeric value of 4.15 × 10-15 eVs.
absorption
Transfer of energy from an electromagnetic field to matter; removal of x-rays from a beam via the photoelectric effect
electromagnetic energy
Type of energy in x-rays, radio waves, microwaves, and visible light
sine wave
Variation in the movement of photons in electrical and magnetic fields
basic wave equation
Velocity = Frequency ×Wavelength and is written as v = fλ.
Which of the following has the highest energy?
X-rays Different from visible light—identified by wavelength—and radiofrequency—identified by frequency—ionizing electromagnetic energy usually is characterized by the energy contained within a photon. An x-ray photon contains more energy, a higher frequency, and a shorter wavelength than visible light or radiofrequency photons.
transluscent material
an scatter light, attenuating or reducing its intensity level
continuum
an uninterrupted (continuous) ordered sequence
If wavelength increases, what happens to frequency?
it decreases. The relationship between wavelength and frequency is an inverse one, meaning as one goes up, the other goes down. In other words, this relationship is explained as the longer the wavelength, then the lower the frequency, or the shorter the wavelength, then the higher the frequency. This inverse relationship explains the wave equation. Note that the wave amplitude is not related to these parameters
Electromagnetic energy includes what types of disturbances in space?(1) Electric(2) Magnetic(3) Mechanical
1 and 2 only Ever present all around us is a field or state of energy called electromagnetic energy. Electromagnetic energy can be defined as an electric and magnetic disturbance traveling through space at the speed of light. Although photons have no mass or form, their electric and magnetic fields are continuously changing.
What differentiates x-rays from gamma rays?(1) Energy(2) Origin(3) Frequency
2 only Ionizing radiation has two types of photons: x-ray and gamma ray. The only difference between these photons is their origins. X-rays are emitted from the electron cloud of an atom that has been stimulated artificially while gamma rays come from inside the nucleus of a radioactive atom. Both are of equal energy and could not be told apart.
Which of the following on the electromagnetic spectrum have the ability to ionize matter?(1) Infrared(2) Radiofrequencies(3) X-rays(4) Gamma rays
3 and 4 only Even though there are several similarities between x-rays and light, never think of x-rays as just another kind of light. X-rays and gamma rays are both different from other portions of the electromagnetic spectrum because their photons have the ability to ionize. Unlike other photons, they can break apart molecules and ionize massive atoms. These effects can be destructive in human tissues
radio frequency
Electromagnetic radiation with frequencies from 0.3 kHz to 300 GHz. Magnetic resonance imaging uses RF in the range of approximately 1 to 100 mHz. RF consists of radio, broadcasting, and communication waves tend to have relatively low energies and relatively long wavelengths.
Which term is defined as a grouping of energies with ranging frequencies and wavelengths?
Electromagnetic spectrum The electromagnetic spectrum is a grouping of radiate energies ranging from frequency ranges of 102 to 1024 Hz. The photons of these various portions of the electromagnetic spectrum differ only in frequency and wavelength. The known electromagnetic spectrum has three regions most important to radiologic science: visible light, radiofrequency, and x- and gamma radiation. The visible light region is important because the viewing conditions of a radiographic or fluoroscopic image are critical to diagnosis. With the introduction of magnetic resonance imaging (MRI), the radiofrequency region has become more important in medical imaging, and naturally, the x-ray region is fundamental to producing a high-quality radiograph.
Structures that transmit x-rays without altering the path of most of the photons are described as radiopaque.
False X-ray photons interact differently with varying anatomical structure densities. The terms radiopaque and radiolucent are used routinely in x-ray diagnosis to describe the visual appearance of these anatomical structures. Structures that transmit x-rays (lungs, soft tissue) are called radiolucent, and structures that absorb x-rays (bone) are called radiopaque.
If 60 waves go by a given point in 1 second, which is the appropriate unit of measure?
Frequency Frequency refers to the number of waves that go by a specific point in one second. One could observe the frequency of a waveform by fixing attention on one point and watching the rises—crest—and falls—valley—of the wave harmonically as it passes the point of observation. This rate of rise and fall is the wave's frequency.
inverse square law formula explained
I1 is the intensity at the first distance (d1) from the source, while I2 is the intensity at the second distance (d2) from the source. In order to apply the inverse square law, you must know three of the four parameters, which consist of two distances and two intensities.
Which end of the electromagnetic spectrum is more likely to exhibit wave characteristics?
Low end Electromagnetic radiations have some characteristics of waves and some characteristics of particles. The higher the energy (e.g., x-rays and gamma rays), the more they act like particles, and the lower the energy, the more they act like waves (e.g., radio waves and microwaves). This "double identity" is referred to as wave-particle duality.
law of conservation of energy
Principle that states that energy may be transformed from one form to another but cannot be created or destroyed; the total amount of energy is constant
law of conservation of matter
Principle that states that matter can be neither created nor destroyed
visible light
Radiant energy in the electromagnetic spectrum that is visible to the human eye the visible light spectrum extends from short-wavelength violet radiation through to long-wavelength red radiation. The color wavelength emitted by visible light is based on how the light photons interact with matter. When a photon of light strikes an object, it sets the object's molecules into vibration. The orbital electrons of some atoms of certain molecules are excited to an energy level that is higher than normal. This electron energy is immediately reemitted as another photon of light in a process called reflection
Which portion of the electromagnetic spectrum tends to have the lowest energy levels and consists of broadcasting and communication waves?
Radiofrequency Radiofrequency (RF) covers a considerable portion of the electromagnetic spectrum. RF consists of radio, broadcasting, and communication waves. Radiofrequencies tend to have relatively low energies and relatively long wavelengths.
attenuation
Reduction in radiation intensity that results from absorption and scattering
radiopaque
Referring to a tissue or material that absorbs x-rays and appears bright on a radiograph
Which term defines the deviation of light photons as it passes from one transparent medium to another?
Refraction Visible, white light is composed of photons ranging in several different wavelengths. If the course of these photons is deviated by passing from one transparent medium to another, like a prism, the photons are separated into different angles, emerging as groups of light of varying colors. This deviation in line of travel is called refraction. It is the cause of many peculiar but familiar phenomena, such as a rainbow.
microwave
Short-wavelength radiofrequency
frequency
The number of wavelengths that pass a point of observation per second
inverse square law
The relationship between distance and intensity (quantity) of radiation (e.g., the intensity of the radiation at any location decreases with the square of its change of distance from the source of radiation). The resulting tripling of a person's separation from a radiation source causes the exposure received by that person to decrease by a factor of 32, or 9.
The law of conservation of matter explains that matter can neither be created nor destroyed but simply transformed.
True According to classical physics, matter can be neither created nor destroyed, a law known as the law of conservation of matter. Einstein and Planck greatly extended these theories. According to quantum physics and the physics of relativity, matter can be transformed into energy and vice versa
What is the term used to describe the lowest point of a wave?
Valley As a wave travels, it moves in an up and down fashion. The highest point of the wave formation is called the crest, while the lowest point of the wave formation is the valley.
Sequence the following members of the electromagnetic spectrum from lowest energy to highest:
Visible light X-rays Microwaves Ultraviolet Radiowaves Infrared
Which portion of the electromagnetic spectrum can be seen and sensed by the human population?
Visible light Visible light occupies the smallest segment of the electromagnetic spectrum, and yet it is the only portion that we can sense directly. The visible light spectrum extends from short-wavelength violet radiation through to long-wavelength red radiation
Planck's quantum theory describes a relationship between what two things?
frequency and energy Max Planck, a German physicist, discovered that one photon at a frequency twice that of a second photon also has twice the energy as expressed by his quantum theory. The Planck's quantum theory expresses that a photon's energy is directly proportional to its frequency.
crest
highest point of a wave form
What happens to wavelength as frequency increases?
it decreases. Three wave parameters—velocity, frequency, and wavelength—are needed to describe electromagnetic energy. The relationship among these parameters is important. A change in one affects the value of the others. This relationship is made simpler because the velocity (speed) of all electromagnetic energies is a constant—the speed of light (3 x 108 m/s). The relationship between wavelength and frequency is an inverse one. In other words, this relationship is explained as the longer the wavelength, then the lower the frequency, or the shorter the wavelength, then the higher the frequency. This inverse relationship explains the wave equation.
x-rays
measures in electron volts (ev)
rate of rise and fall (frequency)
measures in hertz
Electromagnetic energy is a combination of both electric and magnetic fields __ from/to one another in sinusoidal fashion.
perpendicular The nature of electromagnetic energy is that it is a combination of both electric and magnetic fields. These fields are perpendicular, varying 90 degrees from one another, in a sinusoidal fashion with diminishing amplitudes.
How are anatomic structures that absorb x-ray photons described?
radiopaque Varying light-material interactions can easily correlate into how x-ray photons interact with anatomical structures. The terms radiopaque and radiolucent are used routinely in x-ray diagnosis to describe the visual appearance of anatomical structures. Structures that transmit x-rays (lungs, soft tissue) are called radiolucent and structures that absorb x-rays (bone) are called radiopaque
The inverse square law states that intensity will vary as what power of the distance?
second (squared) When light is emitted from a source such as the sun or a light bulb, the intensity decreases rapidly with the distance from the source. Mathematically, this property is called the inverse square law. It states that intensity is inversely proportional to the square of the distance of the object from the source
amplitude
width of a waveform refers to the height of a wave. Amplitude is the maximum height of the wave measured from its average height. A wave with large amplitude is generally stronger than a wave with smaller amplitude.
ionizing radiation has two types of photons
x-ray and gamma ray. The only difference between these photons is their origins. X-rays are emitted from the electron cloud of an atom that has been stimulated artificially while gamma rays come from inside the nucleus of a radioactive atom. Both are of equal energy and could not be told apart.