Computer tomography( CT imaging) X-ray - Causes, symptoms and treatment. MF.

Computed tomography( CT) is a modern method of radiodiagnosis, which allows obtaining a layered image of any human area with a cut thickness from 0.5mm to 10mm, assessing the condition of the organs and tissues under study, localization and prevalence of the pathological process.

The principle of operation of the X-ray computer tomograph is based on the circular transmission of the investigated region by a thin beam of X-rays perpendicular to the body axis, recording the attenuated radiation from the opposite side by the detector system and converting it into electrical signals: passing through the human body, x-rays are absorbed by different tissues to varying degrees. Then X-rays fall on a special sensitive matrix, data from which are read by a computer. The tomograph allows you to get a clear image of several sections of the body, and the computer processes the images in a very qualitative three-dimensional image that allows you to see in detail the topography of the patient's organs, the localization, extent and nature of the disease centers, their relationship to surrounding tissues.

The discovery of X-ray computed tomography( RTT) gave impetus to the development of all digital layer-by-layer methods of investigation: magnetic resonance imaging( MRI), single-photon emission( radionuclide) computed tomography( SPECT), positron emission( PET) computed tomography, digital radiography. Computed tomography( CT) is today the standard leading method for diagnosing many diseases of the brain, spine and spinal cord, lungs and mediastinum, liver, kidneys, pancreas, adrenals, aorta and pulmonary artery and a number of other organs.

Usually " X-ray computed tomography " is simply called " computed tomography ".

Advantages of computed tomography( CT)

Advantages of X-ray computed tomography( CT):

• high tissue resolution - allows us to estimate the change in the radiation attenuation coefficient within 0.5%( in usual radiography - 10-20%);
• there is no imposition of organs and tissues - there are no closed zones;
• allows you to evaluate the ratio of the bodies of the area under study
• application package for processing the acquired digital image allows you to obtain additional information.

Harm of Computed Tomography( CT)

There is always a small risk of cancer from excessive exposure. However, the possibility of accurate diagnosis outweighs this minimal risk.

The effective radial load in computed tomography( CT) is from 2 to 10 mSv, which is the same as, on average, a person receives from background radiation after 3-5 years. Women should always tell their doctor or radiologist if there is any possibility that they are pregnant. Computed tomography( CT scan), in general, is not recommended for pregnant women because of the potential risk to the child.

Breastfeeding mothers after a contrast injection should take a break in breastfeeding for 24 hours.

The risk of serious allergic reactions to contrasting materials containing iodine is extremely rare. But the radiology departments are well-equipped to deal with them.

Because children are more sensitive to radiation, children can only be assigned a computerized tomography( CT scan) to children when absolutely necessary.

There are no absolute contraindications to computed tomography( CT).Relative contraindications to computed tomography( CT): pregnancy and younger children, which is associated with radiation exposure.

Indications for computed tomography( CT) are determined by the attending physician in conjunction with the radiologist who is conducting the study. The examination of the internal organs according to the screening program( preclinical detection of hidden diseases) can be done without the direction of the attending physician. In this case, the radiologist determines contraindications, if any.

When is computed tomography

Computer tomography is being done now more and more often. This method is noninvasive( does not require surgical intervention, it is safe and is used for many diseases.) With the help of computer tomography, it is possible to examine almost any organ from the brain to the bones, often using computer tomography to clarify pathologies revealed by other methods, for example, in sinusitis, curvature of the nasal septumoften first make an x-ray of the paranasal sinuses, and then to clarify the diagnosis - conduct a computer tomography of the nose and paranasal sinuses.

In contrast to the usualX-ray, on which the bones and airborne structures( lungs) are best seen, soft tissues( brain, liver, etc.) are clearly visible on computed tomography( CT), which makes it possible to diagnose diseases in the early stages, for example,

With the advent of spiral and multispiral tomographs, it became possible to conduct a computerized tomography of the heart, blood vessels, bronchi, and intestines.

Computed tomography( CT) in dentistry is intended for detailed examination and accurate diagnosis of dentition and departments of the maxillofacial area, and is necessary for planning surgical interventions for dental treatment and dental implantation operations. High resolution and contrast of computed tomography in comparison with conventional X-ray research make this method the most valuable and highly informative in dentistry.

How is computed tomography( CT)

performed? When preparing for X-ray computed tomography( CT), it is recommended to stop eating food and water about four hours before the study( if you need to take the medicine, you can drink it with a small amount of water).

Computed tomography takes up to 15-20 minutes per study area. In the process of preparation the doctor gives separate recommendations, the implementation of which will make the survey as effective and informative.

Computed tomography( CT) is performed in the supine position. You will be placed on a moving desk for research, which moves through the tunnel. Belts and cushions can be used to help you maintain and maintain the correct position during computed tomography( CT).

Images for computed tomography( CT) are obtained using a narrow rotating beam of X-rays and a system of sensors arranged in a circle, called a gantry. A computer station that processes images is located in a separate room, where the technologist controls the scanner and monitors the progress of the research.

If a study of the abdominal or pelvic organs is performed, the patient is advised to take a contrast agent according to a special scheme. Through the dropper, installed in the ulnar vein, a contrast agent is injected according to the indications. It is recommended to lie still during the tomographic examination, in some cases the doctor may ask to hold your breath for a few seconds. Any movement - breathing or body movement, can lead to defects on a computer tomogram. These defects are like a blurry photo, which is obtained when shooting a moving object.

During the CT scan, the table moves, creating conditions for better scanning of organs and systems. A new modification of tomography, spiral computed tomography( CT), makes it possible to investigate the anatomical region in one breath-holding period and to change the reconstruction step in the subsequent processing of data. You will be alone in the room during computed tomography( CT).However, a technologist or a radiologist will see, hear and speak with you throughout the study. With computed tomography( CT), children can be allowed to parents in a special lead apron to be present in the study room.

After computed tomography( CT) you can return to your normal lifestyle. If you entered contrast material, you will be given special recommendations. The results will be sent to the doctor for further study, diagnosis and treatment plan. The procedure of computer X-ray and magnetic resonance tomography is painless, minimally invasive.

Computed tomography is painless. The only inconvenience - the need to lie without moving from a few minutes to half an hour. Some patients( children, excited patients) can not do this, then they are given a sedative. Computed tomography( CT) is considered a safe method. The dose of X-ray irradiation is relatively small. There is also a very small risk if sedatives and contrast agents are required. The patient should warn the doctor if he has allergies to medicines, iodine, seafood if he suffers from diabetes, asthma, heart disease and thyroid gland.

Computed tomography( CT) is contraindicated in pregnancy. Especially in the first trimester of pregnancy. In rare cases, when no CT scan is necessary( in case of severe trauma, for example), it is still done, but if possible, the uterus is covered with a lead shield. If you are pregnant, be sure to tell your doctor who is conducting the tomography.

MRI examination, in contrast to X-ray computed tomography( CT), is completely harmless. Unlike other methods, the MR tomograph does not have radiation( X-ray) toxicity. However, there are some contraindications to its implementation. First and foremost, this applies to patients who are implanted with a pacemaker, ferromagnetic implants and / or transplants, as well as patients whose weight exceeds 130 kg.

Result of computed tomography( CT) scan

In the process of computed tomography( CT), a detailed image of the organ under investigation will be obtained in detail. A radiologist who has been trained in the conduct and interpretation of radiological research will analyze the images and send the results to your doctor. Your doctor will tell you the results.

The main signs of diseases, detected by computed tomography.

Symptoms of diseases detected by computed tomography are different depending on the organs that are being examined. Thus, in the study of the liver, spleen, pancreas, the main signs of damage to these organs are the heterogeneity of the structure, the presence of foci of change, their number, size, location. The contours of the organs change, they become uneven, fuzzy, bumpy. A certain combination of these signs in diseases of the liver make it possible to recognize with great certainty tumors of the smallest size, cysts, abscesses. Computed tomography helps to diagnose fatty liver degeneration with great certainty. Stones up to 1 mm in diameter are clearly defined when examining the gallbladder. Computer tomography is the leading method for recognizing such pancreatic diseases as chronic pancreatitis and tumors of this organ. In the study of the brain, the increase or decrease in the density of the brain tissue is of primary importance. Reduction of density in limited areas is typical for heart attacks, cysts, abscesses. Increased density is observed with fresh hemorrhages. Focal and diffuse brain changes are well recognized in inflammatory diseases, malformations, brain traumas. Brain changes that develop as a result of processes leading to a decrease in the volume of brain tissue( Huntington's chorea, Wilson-Konovalov's disease, Pick's disease, Alzheimer's disease) are clearly recorded.

Spiral X-ray Computed Tomography( CTD)

In conventional X-ray computed tomography( CT), a single scan creates an image of one layer, the scan cycle is repeated after the next move of the table as many times as the layered images need to be obtained. In the SCT, a continuous movement of the tube around the area under investigation is carried out with a parallel uniform movement of the table with the patient in the longitudinal direction. The trajectory of the movement of the X-ray tube to the longitudinal axis of the object under study takes the form of a spiral.

The rapid rotation of the radiating tube, the absence of intervals between the radiation cycles to advance the table to the next position significantly shorten the study time. This facilitates the study of patients who can not hold their breath for a long time, stay in the apparatus for a long time( patients with injuries, patients in grave condition, sick children), and also increases the capacity of the cabinets.

High scanning speed allows you to get sharper images with less artifacts from physiological movements. The new technology also improved the quality of images of moving organs of the chest, abdominal cavity. Reducing the time of irradiation makes the method of spiral computed tomography( CTD) safer for patients. With spiral computed tomography( CT) scan the entire object, which allows you to obtain an image of any fixed layer from the scanned volume. Spiral X-ray computed tomography( CTD), which allows to investigate the whole given object with a single respiratory arrest, excludes the possibility of escape( "slipping") of the pathological focus from the scanned layer, which provides better detection of small foci in the parenchymal organs.

Spiral CT angiography is the latest achievement in X-ray computed tomography. Unlike conventional computed tomography( CT), the study is performed at the time of intravenous administration of a water-soluble non-ionic contrast medium. Contrast substance is injected into a vein without complicated surgical manipulations, connected with carrying out an intra-arterial catheter to the organ under examination. This allows you to conduct an outpatient study for 40-50 minutes and completely eliminate the risk of complications from surgical manipulation. The radiation load on the patient is sharply reduced and the cost of the study is significantly reduced. CT angiography completely replaces screening( diagnostic) angiography and significantly exceeds ultrasound examination of vessels.

Multispecial computed tomography

MSCT( multispiral computer tomograph) with two X-ray sources is a new type of computed tomography , which allows to carry out studies with high speed and large spatial resolution( up to 0.5 mm) of small and moving structures, suchas coronary arteries.

The method of multispiral computed tomography allows to quickly assess the condition of coronary arteries in patients with various cardiovascular diseases, including after surgery on the vessels of the heart( stenting and shunting), with the detection of the level and degree of narrowing of the lumen of the vessels. At the same time, the quality of the obtained images does not depend on the heart rate, therefore, it is not necessary to take additional medications at the stage of preparation for the study. The study is performed with the introduction of a nonionic iodine-containing contrast agent in a vein.

The examination is performed in two phases - before the contrast agent is administered( the degree of calcification of the coronary arteries is estimated) and during the administration of the contrast medium( assesses the lumen of the coronary arteries, the degree of lesion of the coronary artery walls, stent patency and shunt functionality).

The method of multispiral computed tomography has practically no contraindications. Restriction to the study is the presence of an allergy to iodine-containing contrast preparations.

Advantages of multispiral tomography in front of conventional spiral CT:

• improved temporal resolution;
• improved spatial resolution along the longitudinal axis z;
• increase scanning speed;
• improved contrast resolution;
• increase in signal-to-noise ratio;
• efficient use of X-ray tube;
• large area of ​​anatomical coverage;
• reduction of radiation exposure to the patient.

Reducing the time of CT procedure reduces the need to stay in one position for a long time, for a long time to hold your breath. This is especially important for children, patients with intense pain or with limited movements;in the presence of cardiac and respiratory insufficiency, fear of enclosed spaces( claustrophobia).

Radiation load with multispiral CT with comparable volumes of diagnostic information is less by 30% compared to conventional spiral tomography.

Preparation for the study.

Preparation for CT is only needed when examining the intestine and abdominal cavity and it should be started the day before the study. Before the study, the gut should be cleared of the contents. For this, the patient must take a laxative, such as Fortrans. The doctor conducting the procedure will explain how to take it. Sometimes, instead of taking a laxative, enemas are put, usually one enema is placed on the eve of the study, the second - in the morning, a few hours before it. The day before the study should adhere to the diet - exclude from the diet of solid food and take only liquids( compote, tea, juices).Preparation for CT scan of other organs is not required.