Computed tomography (CT) is a so-called technique of diagnostic imaging which allows you to examine any part of the human body. It is a radiological examination in which the data coming from the passage of X-rays in the "area of the body to be investigated are re-elaborated by a computer to build a" three-dimensional image of the different types of tissue.
In the past, the examination was conducted by making only scans perpendicular to the length of the body, as if it were ideally cut into slices, and it was definite Computed Axial Tomography. From the initials of this name comes the acronym (acronym) TAC, with which it is still commonly called today. For more modern multilayer machines, however, the term is misnomer because computed tomography is no longer alone axial; the images are acquired through the X-ray tube, the element that emits X-rays, which rotates around the person lying on a bed, thus allowing three-dimensional images to be obtained.
CT is used in many medical fields, from neurological to trauma, oncology, gynecology and cardiology. It also allows you to visualize the arteries and veins very well.
Often, to improve image quality, an iodine-based substance called contrast medium. In some cases, depending on the part of the body to be tested, the contrast medium can be administered by mouth (orally) or introduced into the rectum.
CT can be used for:
- ascertaining (diagnosing) bone damage, internal organs, blood circulation problems, stroke, cancer
- have useful information for further investigations and treatments to be performed. For example, in the case of a tumor, it allows you to determine its position, size and shape before undergoing radiotherapy or a biopsy
- follow over time (monitor) the health conditions of a person, for example by checking the size of a tumor during and after treatment
The CT scan should not be considered a tool to be used as a periodic check-up, in the absence of a precise indication from the doctor, because the dose of radiation emitted by the machine can be, in some cases, quite high. It is also necessary to be cautious especially in children and women of childbearing age.
The person who must undergo the CT scan a few days before the exam is informed about any behaviors and analyzes to be performed.
In cases where the investigation involves the use of contrast medium, it is necessary to fast for the four hours prior to its execution and to have carried out the required blood tests. If, on the other hand, its use is not foreseen, no particular precautions must be observed.
The contrast medium can create problems for people suffering from diabetes, kidney failure, liver failure, myeloma. Before performing the examination, generally, the radiologist and / or the anesthetist ask to see blood tests relating to kidney function. You need to tell them even if you are pregnant. In this case, we always try to avoid having a CT scan as there is a remote possibility that X-rays could harm the fetus.
On the day of the exam it is advisable to wear comfortable clothing and avoid jewelry or clothing with metal parts (such as zips) because they will have to be removed.
The CT scan is not painful, in some cases you may feel a little discomfort that disappears within a few minutes if the contrast medium is injected (for example, a sensation of diffuse heat, a metallic taste in the mouth, or a slight sensation nausea).
If the person who has to undergo the investigation is worried, or anxious, or is afraid of feeling claustrophobic, he should not be afraid to communicate it to the radiology technician who, on the contrary, will be able to give him useful advice on how to deal with the investigation peacefully or, if necessary , give her a light sedative.
Depending on the body part to be investigated, you may need to:
- take off your clothes and wear a lab coat
- remove metal objects such as belts, glasses, jewelry, which could interfere with image quality
- do not eat or drink for a few hours before the exam
During the CT scan, the person is usually lying on his back on a bed positioned inside the part of the machine that performs the scan. The machine consists of a ring that rotates around the part of the body to be examined. Unlike nuclear magnetic resonance imaging (NMR), therefore, you do not fully enter the machine and there should be no claustrophobia problems.
The radiology technician manages the examination in an adjacent room. During scanning you need to be still and breathe normally so that the images are not blurry. In some cases, the radiologist may ask you to inhale, exhale, or hold your breath. He is able to hear and speak via an intercom. The scan usually takes 10 to 20 minutes.
After the CT scan, you can go back to your daily habits. In the event that the contrast medium has been injected, it is generally asked to wait at least an hour in the radiology department to be sure that no allergic reaction occurs.The contrast medium is usually harmless and is eliminated through the urine, it is therefore recommended to drink abundantly after the conclusion of the investigation to facilitate its elimination.
CT results are usually not available immediately as the images must be analyzed on a computer and then viewed by the radiologist. After evaluating the images, the radiologist writes the result (report) to be submitted to the doctor who prescribed the survey and who will illustrate it to his client. The time it takes to get an answer varies from a few hours to a few weeks.