Video: X-Rays in Medicine

In this video, we will look at two uses of X-ray radiation in the field of medicine.

10:35

Video Transcript

In this video, we will be discussing X-rays and just how useful they can be in the field of medicine. We’ll be looking at one diagnostic use of X-rays and one use in the treatment of certain illnesses. But let’s begin by recalling what X-rays are in the first place. X-ray radiation, sometimes known as Röntgen radiation after the scientist who discovered, is a form of electromagnetic radiation. X-rays fall in the electromagnetic spectrum between ultraviolet or UV rays, which carry less energy and have a longer wavelength than X-rays and gamma rays, which carry more energy and have a shorter wavelength than X-rays.

Now let’s take a look at one way in which X-rays can be used in the field of medicine. We may already be familiar with X-ray images, which depict the inside of the human body and are most commonly taken when the patient is suspected to have broken a bone. These X-ray images, commonly just called X-rays in everyday language, allow us to quickly and easily see what’s happening inside the human body without actually having to operate on the patient. But exactly how are these image is formed and what do X-rays have to do with them? Well, informing these familiar black and white images, X-ray radiation is fired at our patient, who in this particular case is patiently standing there in the way of these X-rays. And there’s also a screen placed on the other side of the patient.

Now, these X-rays being fired at our patient will penetrate the patient’s skin and pass into their body, at which point they will encounter different body parts. For example, inside the patient’s hand, there are bones, and the rest of the hand we can imagine to be made up off soft tissue. Well, any X-rays interacting with the bone of the patient will be absorbed by the bone. This is because bone contains a lot of calcium, and calcium is a good absorber of X-rays. And this means that X-rays passing through the patient will not be able to get through to the other side if they interact with bone. However, other X-rays which do not interact with bone, i.e., they only pass through soft tissue, will actually be able to penetrate through the patient’s entire body.

In other words, they’ll be able to pass out the other side because soft tissue is not a good absorber of X-rays. And so what we’re saying is that some of the X-rays will be absorbed by the patient’s body. And these will be the ones trying to pass through something like bone or teeth because these are both good absorbers of X-rays. Other X-rays only passing through soft tissue and organs will be able to pass through the patient’s body. And this is where the screen comes in. The screen, originally light in color, changes color whenever X-rays interact with them. In other words, the X-rays that are allowed to pass through the patient’s body will hit the screen behind the patient. And this causes the screen to go darker in color.

Therefore, all of the regions where the X-rays have passed through the patient and interacted with the screen will go darker in color and all of the regions where the X-rays were absorbed, such as, for example, by the bones inside the patient, will remain lighter in color because no X-rays have passed through to those regions. And this is how X-ray images are produced. They’re often useful in helping us see if any cracks or fractures exist in the patient’s bone. And it’s this contrast between parts of the body that do absorb X-rays, such as bones and teeth, and parts of the body that don’t, such a soft tissue organs and flesh, that allows us to produce X-ray images. And this is one very common use of X rays in the field of medicine.

So now that we’ve looked at a way in which X-rays are used to image the inside of the human body, let’s look at how X-rays can be used to treat certain kinds of illnesses. To understand this, though, let’s first recall that X-rays are form of very high energy electromagnetic radiation. In fact, only gamma rays carry more energy than X-rays do. But we should also realize that the electromagnetic spectrum is a continuum. In other words, the energy continuously increases as we go from left to right the way that we’ve drawn it here. This means that even within the part of the electromagnetic spectrum that we’ve called X-rays, there is a range of energies present. This means that there are X-rays with slightly lower energy down this end and X-rays with slightly higher energy down this end. Importantly though, all X-rays are form of ionizing radiation.

Let’s recall that ionizing radiation is radiation that has enough energy to remove electrons from atoms, turning those atoms into ions. This means that as X-rays enter the human body, it is possible that they will interact with some of the atoms forming the human body and ionize these atoms or turn them into ions. This ionization process can end up damaging or destroying the cells that these atoms are making up. And when we’re just imaging the inside of the human body, like we did when we were forming X-ray images, we do not want this ionization to happen. We do not want to damage the human body cells. In that situation, all we’re trying to do is to see what’s happening inside the human body without damaging it in anyway. And so to minimize the risk of any damage occurring to the human body, when we’re imaging, we use low-energy X-rays.

And we can recall that the lower the energy of an electromagnetic wave, the longer the wavelength because on the diagram that we’ve drawn here as we move from left to right, the energy increases. But the wavelength increases in the opposite direction from right to left. So we use low-energy X-rays for imaging purposes to minimize the risk of any damage occurring to the human body. However, in some cases, we actually want to harness the ionizing power of X-rays. And we will, therefore, end up using high-energy X-rays. One such use is an X-ray therapy. This is where high energy X-rays are sent into the human body, usually in very specific locations, to damage the cells that form a cancerous tumor. We want these X-rays to ionize the cells forming this cancerous tumor so that those cancerous cells get destroyed.

In other words then, these high-energy X-rays are used to treat cancer. The reason for this is that cancer cells have a form of genetic mutation that allows them to multiply rapidly. In other words, the tumor will grow in size. And cancer cells don’t even die quickly. So the tumor grows and grows, which is why we use these high-energy X-rays to kill the cancer cells. But when we do so, it’s important to ensure that not damaging any of the patient’s other healthy cells. In other words, we wanna try and make sure that these X-rays are very specifically targeted at the tumor and nowhere else. There are very clever techniques that allow very narrow beams to be targeted at a cancerous tumor whilst minimizing the damage felt by other healthy cells.

For example, if we have lots of narrow beams of relatively weak intensity, all pointed at the tumor, then all of the bits of the body that each beam passes through is not going to be massively affected because, as we said already, the intensity of each beam is weak. However, because all of these beams converge at the tumor, the tumor itself is going to feel the full brunt of all of these X-rays. And because all of these X-rays are high energy X-rays, they’re highly likely to damage the cells in the cancerous tumor, therefore, killing the tumor without damaging too many of the healthy cells. So that’s the second use of X-rays in medicine that we’ll be looking at in this lesson. Once again, it’s known as X-ray therapy. So now that we’ve looked at both X-ray imaging and X-ray therapy, let’s take a look at an example question.

Do the X-rays used in X-ray therapy have a higher frequency, a lower frequency, or the same frequency as those used in X-ray imaging?

Okay, so in this question, we’re comparing the frequencies of X-rays used in X-ray therapy and X-ray imaging. So let’s first recall that, in X-ray imaging, X-rays are sent into a patient’s body because some parts of the body, such as bones and teeth, will absorb X-rays, whereas other parts, such as flesh and soft tissue, will not absorb X-rays. Therefore, some of the X-rays pass out the other side of the human body and then hit a screen placed behind the patient. This then results in an image of the inside of the patient forming on the screen because the regions of the screen that remain white are the regions where no X-rays have interacted with the screen because those X-rays were absorbed by the bone in the patient’s body. Whereas the regions that go dark are regions where X-rays have interacted with the screen because they’ve been able to pass through the patient’s body due to interacting with regions that as soft tissue, which don’t absorb X-rays very well.

And so the end result of this is an image that shows the contrast between regions that do absorb X-rays and regions that don’t absorb X-rays, resulting in an image of the inside of the patient’s body. Now in X-ray imaging, all we’re trying to do is to take an image of the patient’s body as we’ve mentioned already. We do not want to damage the patient’s body using the X-rays that we’re sending into the patient because, remember, X-rays are a form of ionizing radiation, which we can recall is radiation that has enough energy to ionize atoms. Now, if these X-rays that we’re sending into our patient were to ionize lots of the cells in this patient’s body, then this could seriously damage the cells that these atoms were making up, therefore greatly harming the patient. This is exactly what we do not want to happen. We want to minimize the risk of any ionization occurring when we pass X-rays into a patient. And so to minimize this risk, we use low-energy X-rays.

Now, let’s contrast this with X-ray therapy. Let’s say we’ve now got a patient who’s got a cancerous tumor in their body. In this case, what we can do is to use high-energy X-rays and target them towards the tumor specifically so that these high-energy X-rays will have a high chance of ionizing the atoms forming cells in the tumor. This ends up killing the cells in the tumor and therefore shrinking the tumor. In other words, we’re using high-energy X-rays to treat cancer. And so what we’ve realized is that X-ray imaging uses low-energy X-rays, whereas X-ray therapy uses high-energy X-rays.

However, in this question, we’ve been asked to compare the frequencies of the X-rays used in X-ray therapy and X-ray imaging. Well, at this point, we can recall a property of electromagnetic waves, the fact that the energy of an electromagnetic wave is directly proportional to the frequency. In other words, an electromagnetic wave with high energy is also going to have a higher frequency. And from this we can deduce that, in X-ray imaging, we use low-frequency X-rays, whereas in X-ray therapy, we use high-frequency X-rays, which means that the X-rays used in X-ray therapy have a higher frequency than the X-rays used in X-ray imaging. And that is the answer to our question.

So now that we’ve taken a look at an example question, let’s summarize what we’ve talked about in this lesson. Firstly, we saw that X-rays are form of electromagnetic radiation. They are found in the electromagnetic spectrum between ultraviolet or UV light and gamma rays. Secondly, we saw that X-rays with comparatively low energies are used in X-ray imaging to visualize the inside of a patient’s body. Some parts of the body, for example, bones and teeth, absorb X-rays better than other parts. And we use this difference in absorption to form X-ray images. Lastly, we saw that X-rays with comparatively high energies are used in X-ray therapy. These X-rays are targeted at cancerous tumors, thus ionizing the atoms forming the cells in the tumor and killing these cells.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.