Human health is currently exposed to a variety of dangers. To prevent serious illnesses that can even be fatal, examinations should be carried out. Computed tomography is one of the methods that are actively used for these purposes. CT devices come in different types.
General description of the procedure
Immediately it is worth starting with the fact that computed tomography belongs to the group of non-invasive examination methods. This procedure involves the diagnosis of the internal parts of the human body in layers. The essence of the method is that the CT apparatus emits x-rays that can pass through anatomical obstacles of very different densities.
The absorption of such rays takes place with different intensities, which depend on the density of the studied region. Today, computed tomography is one of the most effective methods of examination, allowing to detect a variety of diseases at different stages.
What is the equipment
What does the CT apparatus look like, allowing for such examinations? The device is presented in the form of a rectangular box, which in the center has a hole in the form of a tunnel. The object under investigation, that is, a person, lies on a special retractable table passing through this tunnel. For the examination, the apparatus has a group of special sensors and a narrow rotating beam of radiation. Sensors are placed on a scanned ring called a gantry.
In addition, the CT device has a set of devices responsible for the formation and output of the image. Most often, this complex is located in the next room. Here, a specialist monitors the operation of the scanner and receives information about the progress of the examination.
Serial and spiral units
To date, all CT devices are divided into two groups - sequential and spiral.
To consider them in more detail, it is worth starting with sequential ones, since they were an earlier generation of equipment used for computed tomography. Such equipment made it possible to construct only one section during the examination, which was the result of x-ray radiation. To date, such devices are used extremely rarely, since the procedure takes too much time. In addition, such CT devices are characterized by too much radiation exposure.
The second type of spiral-type devices made it possible to obtain more information in less time; the amount of exposure to humans was reduced. These advantages were achieved precisely due to the spiral effect of radiation due to the mixing of the directions of the scanned tube.
That is, today, if you make a choice which CT apparatus is better, then it can be argued that it is spiral and multislice with the number of layers from 8 to 64. We will discuss them below.
Subtypes of spiral devices
In modern medicine, single-slice or multislice devices are used. Single-slice devices form in one complete circle only one scanning layer. Multislice form at once several slices in one circle.
There are several significant advantages of multi-helical computed tomography machines: the examination speed is much higher, the reduced ionizing effect on the person being examined, the increased area of the anatomical study, and the improved image quality.
Which CT device is currently in use? The development of technology has allowed the creation of equipment with the ability to scan a huge number of layers. Thus, advanced CT units can create from 16 to 64 layers. Such machines are the most common. If we talk about their characteristics, then, for example, 16-slice equipment has speed parameters that are 24 times higher than single-slice or, say, 4 times higher than 4-slice equipment. The time spent on scanning is also significantly reduced (about 30 times). Due to a decrease in exposure, the dose of CT rays also drops significantly.
In order to significantly improve the quality of the resulting image and increase its resolution, as well as further reduce the time spent on diagnostics, aggregates with a number of slices of 64 were introduced into medicine.
The purpose of 64-slice devices
The use of such complex aggregates is of great importance when it is necessary to conduct a tomography of the highest quality. A huge number of sections will allow you to examine all parts of the human body. The most important detail - a large number of layers will allow you to qualitatively check the areas that are constantly in dynamics. These include the heart and bone joints. Due to the operative formation of images obtained from such units, they were able to replace such classic examination methods as angiography and the introduction of cardiac catheters.
Modern equipment allowed for a few seconds to examine the coronary vessels, abdomen, lower pelvis and chest. Modern tomography equipment has the option of contrast enhancement. It allows you to highlight in the picture the smallest details of the vascular system of the brain, kidneys, tumor formations, violation of the integrity of bones and other injuries, ailments.
Today, rarely, but still there are units with a 320-slice mode of operation. The capabilities of such devices are completely at an unimaginable level.
Closed and open type of tomograph
From a structural point of view, all devices for tomography can be divided into two types - indoor and outdoor. If we talk about the first type, then in this case the equipment will have a tunnel form of a closed type. Inside it, the object under investigation will be placed, that is, a person. However, it also happens that people suffer from claustraphobia or are afraid of other reasons, or cannot be examined on this type of aggregate. In such cases, open CT scans are used.
Such an apparatus emits X-rays in a spiral, and there is no closed tunnel in the structure.
CT or MRI?
As it has already become clear, computed tomography is a method of examination using x-rays. However, the use of modern equipment allows to obtain a three-dimensional image, and not two-dimensional.
MRI or magnetic resonance imaging is a procedure that also allows you to get volumetric results of the study. The main difference between the two methods is that MRI uses electromagnetic waves rather than X-rays.
CT and MRI devices, despite the similarity, are used in different cases. Examination on CT equipment is often prescribed in case of serious injuries, for example, metatarsal fracture, wrist, etc. With it, you can detect bleeding, examine the lungs.
MRI can provide more information when examining tumors, you can conduct a detailed study of the human nervous system, identify cysts, inflammatory processes, hernias.
Thus, we can conclude that the difference in the type of radiation is the key between the apparatus for computed tomography and the apparatus for magnetic resonance imaging.
CT scan
Today, another type of examination is used, which is called positron emission tomography or PET-CT. In this case, we are talking about tomography using radionuclide preparations.
If we talk about the PET-CT apparatus, then its work is quite similar to that of a conventional tomograph. The design is a large-sized ring with installed sensors that respond to radiation. Instead of a tunnel hole, the PET-CT has a couch that slides inward. The impact of this equipment is based on the operation of positron emission. If we talk about the dose of radiation, then it will not exceed that which a person will receive when undergoing conventional computed tomography.
What are the benefits of the PET-CT procedure?
Of the main advantages of this procedure and equipment, it is worth highlighting the following: almost 100% accuracy of the study, completely painless, can reveal only incipient ailments, the absence of side effects on the human body.
In the end, it is worth noting that this examination procedure itself is new. It allows you to easily evaluate the performance and condition of the internal organs of a person.
The price of a CT apparatus depends on the number of scanned layers, on the year of manufacture. For example, a 32-slice device from Toshiba costs about 17 million rubles.