The 4 Types of Medical Imaging Someone Would Need

Ever find yourself watching a medical drama on TV and hear something like “this patient needs a CT done stat leaving you to wonder why exactly someone would need that over say an X-ray or MRI? 

The world of medical imaging and diagnostics is a fascinating one, especially when you take a deep dive into why certain techniques are preferred over others for diagnosing specific illnesses. In this short article, I want to highlight the 4 main types of imaging techniques you’ll have heard at some point, and possibly not been 100% sure of what each means. 

These are the imaging techniques we’ll be looking at:

  • CT Scan
  • MRI Scan
  • Ultrasound
  • X-ray

And here is where each excels.

CT Scan

Sometimes referred to as CAT scans, CT stands for computerised tomography. It is where X-rays are combined with computers to produce an image inside the body known as a slice; the idea being that if you were to cut someone open at an angle, it would look just like the image produced. 

Doctors prefer to use CT scans when they want to diagnose problems with bones, certain tissues, and check tumours. The advantage of using CT is that a machine can take multiple X-rays, which a computer can then stack together like building blocks to produce a 3D image, making it better to look in greater detail at tumour growth or to see where best to perform a biopsy.

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MRI Scan

I’d argue that MRI scans are the “geekiest” of the imaging techniques due to how they work. We all have hydrogen in our bodies, as we’re mostly water. In those hydrogen atoms are protons which can be manipulated by magnetism.  When someone sits in the tube for an MRI scan, sudden bursts of radio waves can hit the body and knock those protons out of place. When they fall back in place, the machine can get an idea of what a specific area looks like.

MRIs work wonderfully when a doctor wants to look at specific organs, as protons react to the disruption differently (i.e. the protons in your kidneys move at a different speed when disrupted then the protons in your stomach). It is the preferred method when examining along the gastrointestinal tract.

Many people wonder what the difference between CTs and MRIs are. The simple fact is that the former uses X-rays, which I’ll get to later on, and MRIs use radio waves, which I’ll take a bit more about as I describe ultrasounds.


Sometimes referred to as a sonogram, ultrasounds can be used externally and internally to help doctors diagnose an issue or scan/check on the condition of the body (as they do in pregnancies), and help create an image using high-frequency (hence the term ultra) sounds.

It is best to think of this scan like a sonar signal. It uses soundwaves which are at a higher register than what we can hear. When a pad is pressed over the body, these soundwaves reach different tissue and bounce the sound back to the device. This in turn helps the machine figure out what to show. It’s why it is better for use on moving images, like a baby in the womb or an organ like the heart, as doctors would want to see what’s happening at that moment. 

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Ultrasounds don’t cause any radiation, which is why they’re the preferred method for baby scans. Because they’re in real-time, it can also help if a doctor needed to carry out something like an injection in a sensitive area or to check part of the body after a biopsy has been carried out.


Sometimes referred to as a radiograph, X-rays are the most well-known and oldest of the scan types. When most people think of X-rays, it is easy to envision someone standing behind a screen that lights up to show inside the body, but that’s better left for cartoons like The Simpsons than it is for real life.

When getting an X-ray nowadays, a patient will either lie on a bench or stand upright while a tube is placed in front of the desired area.  In literally a few seconds, images are taken from different angles to get an idea of what the area looks like. It’s best to think of them as photographs, while the other techniques we’ve discussed are more like scans.

There are no side-effects from X-rays (unless a contrast dye is used) and doctors are usually able to give their findings of results straight away.

Learn more about medical imaging

If you’re interested in learning more about any of the techniques I’ve mentioned here, please visit the OneWelbeck Imaging & Diagnostics website. You’ll find a plethora of information on the patient journey for each of these techniques and how the latest technology is changing the way doctors can look at the body.

Learn more about improving your health

As always, don’t forget to check out the health section of the site here to find information and tips about all aspects of health. Recent articles have looked at topics such as how to get a better night’s sleep and how to prevent common dental diseases.

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