When your doctor told you to have a CT scan, did you feel a little scared or curious? "What is this? Will it hurt? Why is this being done?" You probably have a lot of questions coming to your mind. It's actually very common. Many people don't know much about this. So today, let's talk about this CT scan in a very simple way that you can understand.
Simply put, what is a CT scan?
A CT scan is, to be precise, a `Computed Tomography` scan. This is a special medical test used to see things inside our bodies, such as organs, bones, and blood vessels, very clearly. You may have heard of a regular `X-ray`. This CT scan is a method of taking pictures of our bodies using the same kind of `X-ray` rays, but in a much more advanced way.
Think of a loaf of bread. Just like we slice a loaf of bread, a CT scanner takes a bunch of cross-sectional images (slices) of a specific part of our body. Then, a computer puts all these slice-like images together to create a clear three-dimensional (3D) image of what's inside our body. This allows the doctor to pinpoint exactly what's wrong with your body.
What does a CT scan machine look like?
This is a machine that is usually shaped like a large donut. You will be made to lie down on a table in the middle of the machine. Then, as the table slowly moves into the machine, the ``X-ray`` device inside the machine rotates around your body and takes pictures. It is normal to hear a small ``gho... gho...'' sound during this time.
What is the difference between CT, MRI and PET scans?
Many people get confused between these three types of scans. Although all three are tests that look inside the body, the way they work and what they can detect are different. Let's look at this table to understand the differences clearly.
| Scan type | How it works | What is it often used for? |
|---|---|---|
| CT Scan | Three-dimensional (3D) images are created using X-rays and a computer. | To detect bone fractures, cancerous tumors, internal bleeding, blood clots, brain and spinal cord injuries, etc. Very useful in case of an accident. |
| MRI Scan | It uses a strong magnetic field and radio waves. It does not use X-rays. | To diagnose diseases (even cancers that cannot be detected by CT) of organs such as soft tissues, joints, brain, heart, and liver. |
| PET Scan | Images are created by injecting a radioactive chemical (radiotracer) into the body and measuring the metabolic activity of the cells. | It is used to detect cancer cell activity, heart disease, brain disease, etc. at a very early stage. It is also used to see if a disease has spread. |
How is a CT scan done? How long does it take?
You will need to have a scan in a hospital or a special radiology clinic.
The doctor will probably tell you not to eat or drink anything for a few hours before the scan. You will need to wear a special gown provided by the hospital and remove all metal jewelry, such as earrings, necklaces, and rings.
A radiology technologist will perform this test. You will lie down on the bed of the scanner and be slowly guided into the machine. It is important that you remain still during this time, without moving too much . If you move, the images may become blurry. Sometimes you will be asked to hold your breath for a while.
Many people think this takes a long time. But in reality, the scan only takes a few minutes. However, the entire process can take about 30 minutes, including preparation. Sometimes, if you drink a special liquid (contrast), it can take a little longer because it needs to be distributed throughout the body.
What is a CT scan with contrast?
CT scans can easily see solid objects in our bodies, such as bones. But soft tissues, such as the liver and intestines, sometimes don't show up as clearly.
In these cases, doctors use a special dye to make the organs or blood vessels appear clearer in the image. This is called `contrast material.` When this is injected into the body, it appears white on the scan, making the organs very visible.
There are several ways to provide this `contrast` to the body:
- Injection: Directly into a vein. This method is used to examine things like the blood vessels, urinary system, and liver.
- Orally: By giving it as a liquid to drink. This is used to examine things like the digestive tract and intestines.
- As an enema: If the large intestine is being scanned, it is inserted into the body through the anus.
After the scan, the doctor will advise you to drink plenty of water to help the contrast agent leave your body quickly.
What can a CT scan detect? Can it detect cancer?
Yes, a CT scan can detect many conditions, including cancer. Doctors recommend this scan for a variety of reasons.
- Things like complex fractures and bone tumors.
- Monitor changes in conditions such as heart disease, lung disease (emphysema), and liver tumors.
- Identify internal injuries and bleeding that occur in an accident.
- Find the exact location of a tumor, blood clot, infection, or excess fluid inside the body.
- As a guide to planning surgery or radiation therapy.
The role of CT scans in cancer detection
A CT scan is very helpful in diagnosing some types of cancer.
- To find the location of a cancerous tumor.
- To provide information to determine the stage of the cancer.
- To choose the most appropriate location for a biopsy.
- To see if the cancer has come back after treatment.
- To see if the treatment given is successful.
For example, CT scans are very effective in detecting lung cancer, kidney, bladder, ovarian, and stomach cancers.
Are there risks and side effects?
Like any medical test, a CT scan carries some risk, but it is very low .
- Radiation Risk: CT scans use X-rays, also known as ionizing radiation. Studies have shown that long-term exposure to this radiation can cause cancer. However, because the amount of radiation used in a CT scan is so small, the risk of developing cancer from a single scan is very small, about 1 in 2,000 . In general, the benefits of having a scan far outweigh the risks of not having one. Talk to your doctor about this.
- Pregnant women and young children: If you are pregnant, be sure to tell your doctor . If you are having a scan, especially of the abdomen, you may be offered an alternative, such as an ultrasound scan, which does not use radiation. If you are having a scan on a young child, it is a good idea to ask the doctor or technologist if the radiation level of the machine is adjusted to suit them.
- Allergies to contrast: Some people can have an allergic reaction to the contrast dye. Most of the time, these are minor reactions, such as itching or skin rash. Very rarely, a severe reaction that can be life-threatening can occur. For this reason, the medical staff will monitor you for a while after the scan. If you have any allergies to medications, seafood, or iodine, be sure to tell your doctor before the scan.
The most important thing is to inform your doctor if you have diabetes and are taking medication like Metformin, or if you have any kidney disease.
Take-Home Message
- A CT scan is a very useful and advanced medical test that can obtain three-dimensional (3D) images of the inside of our body.
- This is a painless process and usually ends quickly.
- This helps to detect many medical conditions, such as bone fractures, internal bleeding, blood clots, and cancer.
- The risk of radiation is very low, but be open with your doctor about any questions or concerns you have.
- If you are pregnant, have allergies, or have other medical conditions (especially kidney disease or diabetes), be sure to inform your doctor before having the scan.
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