TürkçeComputed tomography is an advanced radiological imaging method that uses X-rays to obtain detailed cross-sectional images of the body. Organs, blood vessels, and bone structures are evaluated at high resolution. It is widely used in diagnosis, disease staging, and treatment planning.
The computed tomography scanning process is performed by moving the patient through the ring-shaped part of the device called the gantry, and the procedure is completed within a short time. Thanks to thin-slice images, brain hemorrhage, signs of trauma, and internal organ injuries can be detected rapidly. It has critical diagnostic value in emergency clinical situations.
Contrast-enhanced computed tomography applications enable clearer visualization of vascular structures and tumoral formations. It is particularly preferred in cancer screening, metastasis investigation, and the evaluation of vascular occlusions. The use of intravenous contrast material is planned according to specific clinical indications.
Diseases in which computed tomography is used include lung infections, pulmonary embolism, kidney stones, and abdominal pathologies. Spinal diseases and complex bone fractures are also examined in detail. It is a guiding method in preoperative anatomical evaluation.
What Is Computed Tomography and How Does It Work?
Seeing inside the human body has been one of medicine’s greatest goals throughout history. The operating principle of computed tomography transforms this goal into reality through highly elegant engineering. The device is generally designed in the shape of a giant doughnut with a large opening in the center. When the patient lies on the movable table inside this ring, the X-ray source within the device begins to rotate rapidly around the patient through 360 degrees. During this rotation, the rays directed through the body are captured by highly sensitive detectors on the opposite side.
Every tissue in our body has a different density. Bones are very hard and block a large proportion of X-rays. The lungs, on the other hand, are filled with air and therefore allow almost all of the rays to pass through. Muscle, fat, and organ tissues absorb the rays at varying rates between these two extremes. These absorption differences collected by the detectors are transferred to highly powerful computers. The computer processes this complex data and displays the body on the screen in millimetric slices, just like slicing a loaf of bread.
These sections seen on the screen are actually a grayscale map. In medical terminology, these shades are expressed using a special unit that indicates tissue density. Areas containing air appear completely black, while bones or calcified tissues appear completely white. Soft tissues, blood vessels, and fatty tissue are distinguished from one another through thousands of different shades of gray between black and white. In this way, even a difference as small as one-tenth of a millimeter is not overlooked. Today’s modern and ultra-fast devices can scan the entire chest while the patient holds their breath for only a few seconds, completely eliminating blurring that may result from the heartbeat or breathing movements.
Why Is Computed Tomography a Fundamental Tool in the Diagnosis of Thoracic Surgery Diseases?
When a standard chest X-ray is taken, all structures from the front to the back of the chest overlap. The ribs, heart, major blood vessels, and lung tissue appear on a single plane, almost hidden beneath one another’s shadows. This may cause a small lesion concealed behind the heart or a problem overlapping with the bony structure of the ribs to be missed. This is the main reason why computed tomography is indispensable in thoracic surgical diseases. Instead of superimposing tissues, tomography separates them into slices.
Thanks to this technology, it becomes possible to examine each structure inside the chest cavity within its own independent space and with three-dimensional depth. In thoracic surgery, the area to be treated is generally one that carries a risk to life, is highly prone to bleeding, and directly affects respiratory function. Therefore, when planning a surgical procedure, the answers to questions such as “Where is the problem?”, “Which blood vessels is it adjacent to?”, and “How close is it to the airway?” cannot be left to chance. Tomography provides precise, clear, and measurable answers to all these questions, maximizing the safety and success of the treatment to be applied.
Why Is Computed Tomography Important in the Diagnosis and Staging of Lung Cancer?
When lung cancer is suspected, knowing where the disease is located and how far it has spread is vital for taking the correct steps. Computed tomography is the most reliable guide at every stage, beginning with the diagnosis of cancer, continuing with the determination of the disease stage, and extending to the selection of the appropriate treatment method. When a mass is detected in the lung, the first consideration is its anatomical characteristics.
The exact diameter of the mass is measured with millimetric precision on tomography sections. How deep the mass lies from the outer membrane of the lung, whether it is in contact with the chest wall, and whether it has progressed toward the heart, major blood vessels, or airway are examined in detail. During these examinations, a special medical dye called contrast material is often administered intravenously. When this dye enters the bloodstream, the vessels become highlighted and clearly visible on the tomography screen. This makes it possible to determine precisely how close the tumor is to the major vessels, whether it surrounds them, and whether the mass can be completely removed surgically.
In addition, the condition of the lymph nodes is critical in staging the disease. The first sites to which cancer usually spreads are the lymph nodes at the entrance of the lung or in the middle of the chest. Tomography shows the size and shape of these lymph nodes very clearly. Lymph nodes that appear larger and more swollen than normal are considered suspicious, and planning is made to obtain samples from these regions. In addition, advanced tomography techniques that measure the level of blood supply to tissue can provide highly valuable clues regarding the aggressiveness of the tumor and its possible response to treatment.
What Role Does Computed Tomography Play in the Examination of Pulmonary Nodules?
Today, with the widespread use of imaging technologies, it has become extremely common to incidentally encounter lesions called “solitary pulmonary nodules” on the scans of people who visit the hospital for a completely different complaint. These round lesions, which are smaller than 3 centimeters in diameter and surrounded by normal, healthy lung tissue, are called nodules. Lesions larger than 3 centimeters are medically evaluated in a different category as masses.
Although the word “nodule” is often concerning, the vast majority of these detected lesions may actually represent the scar of a harmless previous infection, a benign tissue accumulation, or a small calcification. The most critical role of computed tomography here is to act like a giant magnifying glass and help us understand the nature and behavior of this small lesion. The better the structure of the nodule is analyzed, the more possible it becomes to avoid an unnecessary operation or, conversely, to intervene immediately in a dangerous early-stage condition.
Internationally accepted standard guidelines are used in the follow-up of nodules. The degree of risk of the nodules is determined according to tomography findings. While only an annual follow-up tomography scan may be recommended for low-risk, harmless-appearing nodules, the follow-up period may be reduced to three to six months for lesions that appear riskier or more suspicious. If tomography images provide strong signs that the nodule may be dangerous, the patient is referred without delay for additional tests, needle biopsy, or surgery.
Which Features Does Computed Tomography Examine When Distinguishing Benign and Malignant Nodules?
Understanding whether nodules are benign or malignant is a form of detective work. The clues gathered from tomography sections regarding the external appearance and internal structure of the nodule provide very clear information about its nature. Size is the leading clue. The larger the diameter of the nodule, the greater the risk. While the probability that very small lesions are malignant is almost negligible, the risk increases as the size grows.
The border structure of the nodule also reveals a great deal about its character. Nodules with completely smooth, regular, and even borders are generally benign. In contrast, nodules that extend into surrounding tissues with spiky projections, have a star-like appearance, or possess a highly irregular and indented structure are typical of dangerous formations that tend to spread into their surroundings. Calcification patterns within the nodule are also highly decisive. Complete calcification of the nodule or the presence of calcifications resembling popcorn generally indicates harmless residual changes from the past. In addition, nodules with a semi-transparent structure called “ground glass,” which do not appear completely solid on tomography, have the potential to change in character and therefore require much longer and more careful monitoring.
The main morphological characteristics of the nodule examined during evaluation are as follows:
- Size
- Volume
- Border pattern
- Calcification structure
- Tissue density
- Growth rate
How Are Biopsy and Localization Performed Under Computed Tomography Guidance?
No matter how advanced imaging methods become, in some cases it is essential to take a small piece from the relevant area and examine it under a microscope in order to establish a definitive diagnosis. Obtaining this tissue sample without the need for open surgery is called a biopsy. In suspicious masses located in the outermost parts of the lung, away from the airways, a method called “Transthoracic Needle Biopsy” is used, and computed tomography is once again the main tool in this procedure.
The procedure is carried out in a highly planned and precise manner. The patient lies on the table of the tomography scanner, and the area of skin closest to the mass is identified. This region is completely numbed with local anesthesia. A very thin and specialized biopsy needle is then inserted through the skin. At this stage, the physician does not advance the needle blindly. Real-time tomography sections are obtained after every few millimeters of advancement. Without damaging the surrounding healthy tissues, blood vessels, or other vital organs, the tip of the needle is directed with millimetric precision into the exact center of the targeted suspicious mass. The small tissue samples obtained are sent to the pathology laboratory, where a definitive diagnosis is established. Thanks to this method, a diagnosis can be obtained with a very high success rate even from the most difficult-to-reach lesions, and patients can generally return to their normal lives on the same day.
Another major benefit of tomography before surgical interventions is in “localization” procedures. In modern medicine, many operations are now performed using minimally invasive methods through small openings. However, during surgery, it is almost impossible to see or locate by touch with instruments a very small nodule hidden deep within the lung tissue. To solve this problem, the patient is taken to the tomography unit immediately before surgery. Under tomography guidance, the tip of a thin wire advanced from outside the body is placed like a hook directly into the small nodule, or a special dye or marking substance is injected into the area. When the patient is then taken to the operating room, the surgeon follows this wire or the marked area and locates and removes only the problematic region with pinpoint accuracy, without damaging any healthy tissue.
Is Computed Tomography Life-Saving in Chest Trauma?
Severe chest traumas such as traffic accidents, falls from height, occupational accidents, or penetrating injuries are moments in which even seconds are extremely important and the risk to life is very high. Although simple chest X-rays are taken first in emergency departments, these images may be insufficient to show the full extent of the damage caused by the trauma. A small vascular bleed hidden behind the bones or a small bone fragment penetrating the pleural membrane may be overlooked on standard films. In these emergency situations, computed tomography acts like a lifeline, revealing all hidden injuries with exceptional clarity.
One of the most common consequences of trauma is rib fractures. Tomography does not merely show how many ribs are broken; it also maps in detail whether the broken bone ends have damaged the lung tissue or caused tears. Particularly in serious conditions such as “flail chest,” in which multiple ribs are broken in several places, disrupting the integrity of the chest wall and making breathing impossible, the decision as to whether the bones should be surgically stabilized with titanium plates is made entirely according to tomography images.
The accumulation of blood inside the chest cavity at the time of trauma is another frequently encountered life-threatening condition requiring emergency intervention. Tomography measures the volume of blood accumulated inside and provides information about whether the bleeding is continuing. If the amount of bleeding exceeds a certain threshold or has formed a clotted mass, the decision is made to take the patient for emergency open surgery without delay. In fractures of the breastbone, examining these detailed sections is again the only definitive way to understand whether the heart or the major arteries located immediately behind it have been damaged.
The main conditions detected during post-trauma evaluation are as follows:
- Rib fractures
- Bruising of lung tissue
- Bleeding inside the chest
- Air leakage into the pleural cavity
- Breastbone fractures
- Pericardial injuries
How Is the Degree of Chest Wall Deformity Measured with Computed Tomography?
Pectus Excavatum, commonly known as “funnel chest,” is a deformity characterized by excessive inward collapse of the breastbone located at the front of the chest. This condition is not only a cosmetic problem; it may also place physical pressure on the heart and lungs inside the chest, reducing respiratory capacity and causing rhythm disorders. Mathematical data provided by computed tomography are used to measure the severity of this internal pressure caused by the depression and to make a decision regarding surgery.
For this purpose, a special standardized calculation called the “Haller Index” is performed on tomography images. While examining the sections, the widest right-to-left internal distance of the chest is measured. Then, the shortest horizontal distance between the point where the breastbone is most deeply depressed, meaning the point where it is closest to the heart, and the spine is measured. The widest diameter is divided by this short distance to obtain an index value. If the resulting value is above a certain level, for example 3.25, this demonstrates that the internal pressure is clinically significant. Thanks to this measurement, the decision as to whether the condition should be monitored with exercises or surgically corrected by placing a steel bar inside the chest is made entirely on the basis of objective and scientific data.
Why Is Computed Tomography Preferred in Diaphragm Diseases?
The diaphragm, the primary muscle that separates the chest cavity from the abdominal cavity like a roof and enables us to breathe, appears only as a thin line or dome on standard X-ray images because of its horizontal position. Due to its anatomical structure, tears, herniations, or structural weaknesses in this area cannot always be clearly understood using conventional methods. Advanced software reconstructs the thousands of millimetric sections obtained by the tomography scanner from different angles and in three dimensions, allowing every curve of the diaphragm region to be examined in detail.
Tears in the diaphragm caused particularly by congenital muscle weakness or severe trauma may have dangerous consequences. Because the pressure of the organs inside the abdomen is higher than the pressure in the chest cavity, portions of the stomach or intestines may pass through these tears and move into the chest cavity where the lungs are located. This condition is called a diaphragmatic hernia. Tomography shows within seconds which organ has shifted, how far it has moved, and whether it has become trapped. Tomography guidance is also used to investigate the underlying causes of conditions in which the diaphragm cannot perform its function and is pushed upward because the nerves stimulating it have become paralyzed.
The main conditions examined with tomography in the diaphragm region are as follows:
- Diaphragmatic hernias
- Diaphragm paralysis
- Diaphragm muscle tumors
- Traumatic tears
- Nerve root compression
How Is Computed Tomography Angiography Used in Emergency Vascular Diseases?
The chest contains the largest and most vital blood vessels in our body. In patients who present to the emergency department with complaints such as sudden severe chest pain, back pain, shortness of breath, or coughing up blood, it is necessary to distinguish within minutes whether the source of the problem is a heart attack or another potentially fatal vascular condition. In such situations, the “Computed Tomography Angiography” (CTA) method, performed by administering contrast material through an arm vein and visualizing the inside of the vessels with exceptional clarity, has a life-saving role.
One of the most common emergencies is pulmonary embolism. This disease generally occurs when a blood clot formed in the deep veins of the legs breaks away, travels through the bloodstream to the main arteries of the lungs, and blocks them. Contrast-enhanced tomography visualizes the movement of the contrast material through the vessels and demonstrates within seconds where the blockage, known as a filling defect, is located. By instantly determining the location and size of the clot, blood-thinning treatment can be started immediately, or the clot can be surgically removed if necessary.
Another major emergency occurs when the wall layers of the aorta, the body’s largest artery, tear and blood fills the space between these layers. This condition, called aortic dissection, is a surgical crisis in which every second counts. Computed tomography angiography maps exactly where the tear begins, its extent, and how it affects the branches leading to the heart and other organs. Depending on the location of the tear, the decision as to whether the patient should urgently undergo open-heart surgery with the heart stopped or whether a stent should be placed inside the vessel through a minimally invasive approach from the groin is made entirely under the guidance of these detailed tomography images.
How Does Computed Tomography Guide Three-Dimensional Modeling and Robotic Surgery?
Thanks to breathtaking advances in medical technology, modern thoracic surgery has entered an era in which “personalized” operations tailored to each patient’s individual anatomy are performed instead of “standard” procedures. At the foundation of this major leap is the processing of tomography data with powerful engineering software and its conversion into three-dimensional models. Particularly in lung cancers detected at an early stage, removing only the much smaller subregions, or segments, where the tumor is located has become more prominent instead of completely removing a large portion of the lung, such as an entire lobe. In this way, the patient’s healthy lung tissue is preserved, and postoperative quality of life is improved.
However, the network of blood vessels and airways inside the lungs differs from person to person, just like a fingerprint or the branches of a tree. Before these lung-preserving operations called segmentectomies, the patient’s tomography sections are uploaded to specialized computer programs, creating an exact “digital twin” of the organ. Long before entering the operating room, the surgeon rotates and examines this three-dimensional model from every angle on a computer screen and individually marks the vascular branches surrounding the tumor. The operation is virtually rehearsed in advance in a virtual reality environment.
This extraordinary technology is also fully integrated with robotic surgery, including da Vinci systems. While the surgeon controls the precise robotic arms inserted into the patient’s body through incisions only one or two centimeters in size, the screen at the surgical console displays this three-dimensional digital map obtained from tomography alongside the patient’s real-time image. When working in the confined spaces of the chest cavity and within millimeters of vital vessels and nerves, this high-resolution navigational support provided by tomography reduces the margin of error to virtually zero and elevates surgical safety to an unprecedented level.
Is There a Radiation Risk During Computed Tomography?
When computed tomography is discussed, the first concern that naturally comes to many people’s minds is radiation. Tomography devices do, of course, use X-rays, which are a form of ionizing radiation, to establish a diagnosis. The radiation doses emitted by older-generation devices used in previous years were relatively higher and could justifiably be a source of concern. However, modern medical engineering has taken extraordinary steps in recent years to solve this problem. Today, all radiological imaging procedures are performed in strict accordance with the “ALARA” principle, meaning “As Low As Reasonably Achievable,” which forms the basis of international safety standards.
New-generation, advanced-technology tomography devices contain special hardware-based filtering systems. In addition, the main revolution has occurred in software. Thanks to artificial intelligence-assisted image enhancement algorithms, even when the device sends a very low dose of X-rays into the body, the computer can process these weak signals and transform them into extremely bright, clear, and high-quality images. The amount of radiation received during modern “low-dose lung tomography” examinations has decreased to levels almost equivalent to the natural background radiation a person receives from the environment, sunlight, or soil over a few months, or even close to that of a standard chest X-ray.
When radiation is evaluated, the balance between “benefit and risk” is always considered. Compared with the negligible level of radiation risk emitted by modern devices, the benefits provided by tomography are incomparably greater. Particularly in high-risk groups consisting of people above a certain age who have smoked for many years, these low-dose tomography scans are used almost like an early warning system. Very early-stage cancer cells or suspicious nodules that produce no symptoms and progress silently can be detected in time through these screenings.
Frequently Asked Questions
Prof. Dr. Alper Fındıkcıoğlu graduated from Istanbul University Faculty of Medicine and completed his thoracic surgery residency at Dr. Siyami Ersek Hospital. He began his academic career at Başkent University in 2005; he received the title of associate professor in 2014 and professor in 2022. He has extensive experience in lung cancer, chest wall diseases, and minimally invasive surgery. Since 2024, he has been continuing his professional work at Acıbadem Hospital.
