X-ray waves ( wavelength, frequency, amplitude)

Описание: Check out the BEST NEW RADIOGRAPHY BOOK https://tinyurl.com/RadPhysicsMastery , to help one your ARRT registry. Wave properties for rad techs include first the basic concepts of amplitude, wavelength and frequency. Where the amplitude is the height of the wave, the wavelength is the length of time before the wave repeats and the frequency is how quickly the wave is oscillating and is inversely proportional to the wavelength.

For more information on the basic physics of x-rays such as wave properties and inverse square law see our post https://howradiologyworks.com/basic-x... .

In this video we cover the basics of the wave properties and will go more into the x-ray specific details in future videos.

The x-rays that are produced by diagnostic x-ray equipment have a lot in common with the visible light that we are all very familiar with. As children we all learned about ROYGBIV, which are the different colors of light in order from lowest energy to highest energy (also the longest wavelength to shortest wavelength, more on that to come).

This visible light is just a small portion of all the electromagnetic radiation. The spectrum of electromagnetic waves changes gradually from lowest energy (radio waves and microwaves) to the highest energies (x-rays and gamma rays).

At the bottom of this figure there is a schematic which shows the whole electromagnetic spectrum. On the left of the figure are the lowest wavelengths (highest energies). On the right of the figure are the highest wavelengths (lowest energies).

X-Rays, used for diagnostic imaging in CT scanners, have average energy around 60 keV which is 10,000 times higher than the energy of regular light we see around us.

So, x-rays are electromagnetic radiation just like the light around us but with much higher energy.

Because x-rays have much higher they have shorter wavelength. Since their wavelength is so short in most scenarios we can treat x-rays like particles traveling through space (i.e. just ignore the fact that they are really waves). We call each of these individual packets x-ray photons.

Rad Take-home Point: X-rays are part of the electromagnetic spectrum just like visible light. X-rays can be treated as wave or particles (photons) since their wavelengths are so short.

Chapters:
00:00 Intro waves in medical imaging
01:17 Wavelength of waves
01:44 Amplitude of waves
02:15 Frequency of waves
02:37 Characteristics of wave summary
03:30 Outtakes

As we mentioned above x-rays can be treated like waves or particles, and therefore for completeness we want to describe the wave characteristics of x-rays. X-rays are alternating electric and magnetic waves that are traveling in perpendicular planes. But to make things simpler in the figures we will draw just a single wave as that is easier to visualize.


Electromagnetic waves have fundamental properties – repeating peaks and valleys with certain: amplitude and a frequency (directly related to the Energy, and inversely related to the wavelength).

The waves repeat and the distance for the wavelength to repeat. Therefore, the distance from one valley to the next valley is the wavelength. Likewise, the distance from one peak to the next peak is also the wavelength.

The plots in the wave figure show the height or amplitude of the wave as a function of time. The number of times that the wave pattern repeats in a given time is called the frequency (f). So, longer wavelengths have lower frequencies because they have less peaks in a given time.

Energy of x-rays depends directly on its frequency (E~f) and inversely related to wavelength (E~1/λ). Electromagnetic waves with higher frequencies have proportionally higher energies.

What if we compare the two waves and ask which has the higher energy? The wave with the shorter wavelength, will have higher frequency. Since we know that the energy scales directly with the frequency we know that the wave that has the shorter wavelength will have higher energy.

For instance, violet light has a shorter wavelength than red light and thus violet light has higher energy. Likewise, a 60keV x-ray photon and a 30 keV x-ray photon have the same relationship where the wavelength of the 60keV x-ray is smaller. The same principles apply when comparing electromagnetic radiation at different parts of the spectrum.

Rad Take-Home Point: Waves with shorter wavelengths oscillate more in a given time and have a higher frequency (f ~1/λ) and a higher energy (E~f and E~1/λ).