What is a CT scan?
Computed Tomography, commonly known as CT Scan, is a diagnostic imaging method that uses a combination of X-rays and computer technology to create images inside the body. In this method, high-precision images of different parts of the body including bones, muscles, fat, organs, arteries and veins are shown.
CT scans are of higher quality than standard X-rays. In a standard X-ray, a beam of energy is directed towards the part of the body that is being studied, and then a plate that is located on the other side of the body part receives the rays and the tiny fluctuations of the rays after passing through the skin, bone, It examines and processes muscle and other tissues. Although a lot of information is obtained from standard X-rays, many details about internal organs and other tissues are not available in this way.
In a CT scan, X-rays move around the body in a circular manner. This method enables more viewing angles of an organ or tissue and provides far more details. The information from the rays is then sent to a computer unit that analyzes the information and displays it in two-dimensional form on the screen. Newer technologies and advanced software make such 3D imaging possible.
CT scans are generally used to diagnose tumors, check for internal bleeding, or check for other internal injuries, as well as take samples of tissue or secretions.
?Why is a CT scan sometimes prescribed with an injection
CT scans are performed with contrast (injection) and without contrast. “Contrast” is a substance that is used orally or injected (through an IV tube) and will result in greater clarity of the desired organ or tissue in the final image. CTs with contrast generally require the patient not to eat for several hours before the imaging, although your doctor will inform you about this at the time of administration.
If you have had a reaction to any type of material used for contrast in the past, or if you have kidney problems, you should inform your doctor about this. Reports of seafood allergy do not interfere with the use of iodinated contrast agents. Also tell your doctor if you have any medical complications or problems or have been sick recently.
?How do I prepare for a CT scan
If you have a Computed Tomography Angiography (CT angiography) and Virtual Colonoscopy (virtual colonoscopy) ahead, you will be given special preparation time.
Precautions: If you are pregnant or think you might be pregnant, please inform your doctor before making an appointment.
Dressing: You will be asked to wear a disposable sterile dress, in which case, you will be given a special dress. Please remove all metal objects from the body if possible and leave jewelry and other valuables at home.
Injectable material: Your imaging may have been requested with contrast material. The injected substance helps the radiologist in diagnosing tissues and complications.
Some patients should not use iodine-based contrast agents. If you have a history of kidney problems, please inform the radiologist in advance. We may be able to perform non-contrast imaging or choose an alternative imaging method.
The most common type of CT scan with contrast is CT enterography, in which, in addition to injecting contrast material, a certain amount of contrast material must also be consumed orally (by mouth). The amount of contrast material consumed by The higher you are, the easier it will be for the radiologist to diagnose your digestive tract.
Allergies: If you have any history of sensitivity (allergic reaction) to any type of contrast material, please inform the radiologist before making an appointment. If your allergic reactions are anaphylaxis (severe allergic reaction), injectable contrast will not be prescribed for you, but if your reactions are minor, it is possible to use contrast by taking anti-allergic tablets before imaging. In this case, you will be informed about the medication schedule during the appointment.
Eating and drinking: If your imaging is prescribed without contrast, you can continue to eat, drink, and take your medications as before.
If your doctor has prescribed a CT scan with injection, avoid eating for three hours before imaging. We recommend drinking clear drinks. You can also use the medicines prescribed by the doctor before the imaging.
Patients with diabetes: People with diabetes should eat breakfast or a light lunch three hours before imaging. Depending on the type of diabetes medications you are taking, you may be asked to stop taking them 48 hours before the imaging. More details will be provided to you when you receive your appointment.
Medicines: All patients can continue taking their medicines according to the previous routine.
?What are the risks of a CT scan
If you are pregnant or think you might be pregnant, you should discuss this with your doctor. The amount of radiation used in a CT scan is small, but if you are concerned about it, ask your doctor about the amount of radiation and its relationship to your disease.
If you suffer from claustrophobia (fear of tight spaces), discuss the issue with your doctor. In this case, you may be prescribed sedatives.
?What happens during a CT scan
CT scans are performed either in the hospital or as a referral to a specialized imaging center. The imaging process can be different according to your disease and your doctor’s schedule, but it is generally done with the following process:
- You will be asked to put your clothes in a plastic bag and put on special disposable clothes provided by the center. Also, before leaving home, remove all metal objects and jewelry from your body and leave them at home.
- If your imaging is prescribed with contrast, it is necessary to have a suitable IV-line (intravenous) in the arm before the injection (the IV-line will be connected to you in the center), in which case the contrast will enter the body through the IV. For oral contrast, the contrast liquid will be delivered to you by the reception staff before imaging; Sometimes, the contrast material may be used rectally.
- You lie on a scanning bed that moves on a pivot toward the machine’s circular opening.
- The technician is present in the control room near the device and is in your direct view through a window, and can also communicate with you through the speakers built into the device.
As the scanner rotates around you, X-rays pass through your body in short intervals, and you may hear clicking sounds, which is completely normal.
- A sensor measures the amount of radiation that passes through your body. Then this information is sent to the computer and after processing, they are converted into images. Images that can be interpreted by a radiologist.
- It is important that your body remains completely still during the scan, so you may be asked to hold your breath at times to get better images of your body.
If you have received contrast material through an IV, you may experience feelings of paleness, a salty or metallic taste in your mouth, a mild headache, dizziness, or nausea, which are normal and should not last more than a few minutes.
- Notify the CT scan technician if you experience shortness of breath, excessive sweating, numbness, or palpitations.
- When your imaging is finished, get off the bed with the help of the staff.
- After the end of the imaging, if the IV line is connected to your hand to inject the contrast material, it will be disconnected from your hand.
- The process of doing a CT scan alone does not bring pain, but you may experience some numbness or mild pain due to immobility during the imaging, especially if you have a pre-existing injury or surgery. The technician will do everything possible to increase your comfort and reduce your imaging time.
What happens after a CT scan?
If contrast materials are used for contrast, any side effects or reactions of your body to these materials such as itching, swelling, skin irritations, or breathing problems may be observed for a short period of time.
If you notice pain, redness, or swelling at the injection site after returning home, you should discuss the issue with your doctor because these symptoms may indicate infection or other reactions.
Generally, there are no special care behaviors after CT scan. You can continue with your normal diet and activities as before unless your doctor prohibits such activities.
Your doctor may prescribe additional or alternative prescriptions depending on your medical history.
?What are the advantages of CT scan technology
High Resolution CT: This type of CT scan uses very thin layers (less than two millimeters), which by producing more details, is very useful for certain cases, including pulmonary complications.
Spiral or rotational CT scan: When performing this type of imaging, both the machine and the patient (on a moving bed) are constantly moving. When the rays move around the patient in a circular manner, the resulting images have more contrast and quality, which leads to a better diagnosis by the doctor.
CT-angiography (Computed Tomography Angiography): Angiography (or arteriography) is a method of imaging blood arteries. In this method, instead of standard X-rays in fluoroscopy, CT scan technology is used for imaging.