What is a CT scan and how does it work. How does CT imaging differ from standard X-rays. Why are CT scans sometimes performed with contrast media. How should patients prepare for a CT scan examination.

Understanding CT Scans: Advanced Medical Imaging Technology

Computed Tomography (CT) scans represent a sophisticated medical imaging technique that provides detailed views of the body’s internal structures. This non-invasive procedure combines X-ray technology with advanced computer processing to create cross-sectional images of bones, blood vessels, and soft tissues.

How does a CT scan differ from a standard X-ray? While both use X-ray radiation, CT scans offer significantly more detail. Standard X-rays project a single beam of radiation through the body onto a film, producing a flat, two-dimensional image. In contrast, CT scanners rotate around the patient, capturing multiple images from different angles. These images are then digitally reconstructed to create detailed, three-dimensional representations of the body’s interior.

Key Features of CT Scans:

• High-resolution imaging of bones, soft tissues, and blood vessels
• Ability to visualize internal structures in multiple planes
• Rapid scan times, often completed in minutes
• Non-invasive procedure with minimal discomfort
• Valuable tool for diagnosing a wide range of medical conditions

Applications and Uses of CT Scans in Modern Medicine

CT scans have become an indispensable tool in modern medical diagnostics and treatment planning. Their versatility and ability to provide detailed images make them useful in various medical specialties.

What are some common reasons for ordering a CT scan? Physicians may request CT scans to:

• Diagnose or monitor the progression of tumors
• Detect internal injuries or bleeding after trauma
• Evaluate the effectiveness of treatments for various conditions
• Guide biopsies and other minimally invasive procedures
• Plan radiation therapy or surgical interventions
• Identify abnormalities in blood vessels, such as aneurysms

In what medical specialties are CT scans particularly useful? CT imaging plays a crucial role in fields such as oncology, neurology, cardiology, and orthopedics. For instance, in oncology, CT scans help detect, stage, and monitor cancer. In neurology, they can reveal brain abnormalities related to strokes or tumors. Cardiologists use specialized cardiac CT scans to assess heart function and coronary artery disease.

The CT Scanning Process: What Patients Can Expect

Understanding the CT scanning process can help alleviate patient anxiety and ensure a smooth examination. The procedure is generally quick, painless, and non-invasive.

Steps in a Typical CT Scan:

1. Patient preparation (including removal of metal objects and changing into a gown)
2. Positioning on the CT scanner table
3. Administration of contrast media, if required
4. Brief scan time as the table moves through the scanner
5. Review of images by a radiologist

How long does a CT scan usually take? Most CT scans are completed within 10 to 30 minutes, depending on the area being examined and whether contrast is used. The actual scanning time is often just a few minutes.

Is a CT scan painful? CT scans are generally painless. Patients may experience slight discomfort from lying still on the scanner table or from the insertion of an IV line for contrast administration. Some individuals may feel warm or experience a metallic taste in their mouth during contrast injection, but these sensations are temporary.

Contrast Media in CT Scans: Enhancing Image Quality

Contrast media, sometimes called contrast agents or dyes, are substances used to improve the visibility of internal structures during CT scans. They work by temporarily altering how X-rays interact with the body, highlighting specific areas and making abnormalities more apparent.

Why do some CT scans require contrast media? Contrast agents are used to:

• Enhance the visibility of blood vessels and vascular structures
• Improve the detection of tumors and other soft tissue abnormalities
• Highlight differences between normal and abnormal tissue
• Provide functional information about organ systems

What types of contrast media are used in CT scans? The two main types are:

1. Iodine-based contrast: Administered intravenously, this type is commonly used for enhancing blood vessels and soft tissues.
2. Barium-based contrast: Usually given orally or rectally, this type is used primarily for gastrointestinal studies.

Are there risks associated with contrast media? While contrast agents are generally safe, some patients may experience allergic reactions or kidney problems. It’s crucial to inform your healthcare provider of any allergies or kidney issues before undergoing a contrast-enhanced CT scan.

Preparing for Your CT Scan: Essential Guidelines

Proper preparation is key to ensuring a successful CT scan. The specific instructions may vary depending on the type of scan and whether contrast media will be used.

General Preparation Guidelines:

• Inform your doctor of any allergies, medications, or medical conditions
• Remove metal objects, including jewelry and dental appliances
• Wear comfortable, loose-fitting clothing
• Follow any fasting instructions provided by your healthcare team
• Arrive at the imaging center at the scheduled time

How should patients prepare for a CT scan with contrast? If your scan requires contrast media, you may be asked to:

• Fast for several hours before the exam
• Drink clear liquids to stay hydrated
• Avoid certain medications that may interact with the contrast
• Inform the technologist of any previous reactions to contrast agents

What precautions should pregnant women take regarding CT scans? Pregnant women should inform their healthcare provider before undergoing a CT scan, as radiation exposure may pose risks to the developing fetus. In many cases, alternative imaging methods such as ultrasound or MRI may be recommended.

Radiation Exposure in CT Scans: Balancing Benefits and Risks

While CT scans provide invaluable diagnostic information, they do involve exposure to ionizing radiation. Understanding the potential risks and how they compare to the medical benefits is essential for patients and healthcare providers alike.

How much radiation is involved in a typical CT scan? The radiation dose from a CT scan varies depending on the type of exam and the area of the body being scanned. Generally, a single CT scan exposes patients to more radiation than a conventional X-ray but less than that received from natural background radiation over several months to a year.

Minimizing Radiation Exposure:

• Using the lowest radiation dose necessary to obtain diagnostic-quality images
• Limiting scans to the specific area of interest
• Avoiding unnecessary repeat scans
• Employing alternative imaging methods when appropriate
• Utilizing advanced CT technologies that reduce radiation exposure

Do the benefits of CT scans outweigh the radiation risks? For most patients, the diagnostic benefits of a medically necessary CT scan far outweigh the small increased risk from radiation exposure. However, healthcare providers should always consider the cumulative effects of multiple scans, especially in children and young adults who are more sensitive to radiation.

Interpreting CT Scan Results: From Images to Diagnosis

After a CT scan is completed, the images are carefully analyzed by a radiologist, a physician specially trained in interpreting medical imaging studies. This process is crucial for translating the visual information into a meaningful diagnosis or treatment plan.

Steps in CT Scan Interpretation:

1. Image acquisition and reconstruction
2. Review of patient history and clinical information
3. Systematic examination of the CT images
4. Comparison with prior imaging studies, if available
5. Consultation with other specialists, if necessary
6. Generation of a detailed radiology report

How long does it take to get CT scan results? The time frame for receiving results can vary depending on the urgency of the case and the complexity of the findings. In emergency situations, preliminary results may be available within minutes. For routine outpatient scans, it typically takes a few days for the radiologist to analyze the images and prepare a comprehensive report.

What information is included in a CT scan report? A typical CT scan report contains:

• Patient demographics and clinical history
• Description of the imaging technique used
• Detailed findings for each anatomical area examined
• Comparison with any previous imaging studies
• Impression or conclusion summarizing the key findings
• Recommendations for follow-up or additional testing, if needed

How are CT scan results communicated to patients? Usually, the referring physician receives the radiology report and discusses the findings with the patient. This allows the doctor to interpret the results in the context of the patient’s overall health and to explain any implications for diagnosis or treatment.

Advances in CT Technology: Improving Diagnosis and Patient Care

The field of CT imaging continues to evolve rapidly, with technological innovations enhancing image quality, reducing radiation exposure, and expanding clinical applications. These advancements are transforming the way healthcare providers diagnose and treat various conditions.

Recent Innovations in CT Technology:

• Dual-energy CT: Provides additional tissue characterization capabilities
• Spectral CT: Enables material decomposition and improved contrast resolution
• Ultra-high resolution CT: Offers unprecedented detail for small structures
• AI-assisted image reconstruction: Enhances image quality while reducing radiation dose
• 4D CT: Captures dynamic processes like cardiac motion or blood flow

How are these advancements improving patient care? These technological developments are leading to:

• More accurate and earlier detection of diseases
• Reduced need for invasive diagnostic procedures
• Lower radiation doses without compromising image quality
• Expanded applications in fields like cardiology and oncology
• Improved workflow efficiency and faster scan times

What future developments can we expect in CT imaging? Ongoing research focuses on further reducing radiation exposure, improving spatial and temporal resolution, and integrating advanced data analysis techniques. The integration of artificial intelligence and machine learning algorithms is expected to revolutionize image interpretation and assist in personalized treatment planning.

As CT technology continues to advance, it promises to play an increasingly vital role in modern medicine, offering unprecedented insights into the human body and facilitating more precise, personalized healthcare interventions. Patients and healthcare providers alike can look forward to safer, faster, and more informative CT examinations in the years to come.

Computed Tomography (CT) Scan | Johns Hopkins Medicine

What You Need to Know

• A CT scan is a diagnostic imaging exam that uses X-ray technology to produce images of the inside of the body.
• A CT scan can show detailed images of any part of the body, including the bones, muscles, organs and blood vessels.
• CT scans can also be used for fluid or tissue biopsies, or as part of preparation for surgery or treatment.
• CT scans are frequently done with and without contrast agent to improve the radiologist’s ability to find any abnormalities.

What is a CT scan?

Computed tomography is commonly referred to as a CT scan. A CT scan is a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce images of the inside of the body. It shows detailed images of any part of the body, including the bones, muscles, fat, organs and blood vessels.

CT scans are more detailed than standard X-rays. In standard X-rays, a beam of energy is aimed at the body part being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle and other tissue. While much information can be obtained from a regular X-ray, a lot of detail about internal organs and other structures is not available.

In CT, the X-ray beam moves in a circle around the body. This allows many different views of the same organ or structure and provides much greater detail. The X-ray information is sent to a computer that interprets the X-ray data and displays it in two-dimensional form on a monitor. Newer technology and computer software makes three-dimensional images possible.

CT scans may be performed to help diagnose tumors, investigate internal bleeding, or check for other internal injuries or damage. CT can also be used for a tissue or fluid biopsy.

Why are CT scans sometimes ordered with contrast?

CT scans may be done with or without contrast. Contrast refers to a substance taken by mouth or injected into an IV line that causes the particular organ or tissue under study to be seen more clearly. Contrast examinations may require you to fast for a certain period of time before the procedure. Your doctor will notify you of this prior to the procedure.

You will need to let your doctor know if you have ever had a reaction to any contrast media and/or any kidney problems. A reported seafood allergy is not considered to be a contraindication for iodinated contrast. If you have any medical conditions or recent illnesses, inform your doctor.

How do I prepare for a CT scan?

If you are having a computed tomography angiography (CTA) or a virtual colonoscopy, you will be given specific instructions when you make your appointment.

PRECAUTIONS: If you are pregnant or think you may be pregnant, please check with your doctor before scheduling the exam.

CLOTHING: You may be asked to change into a patient gown. If so, a gown will be provided for you. Please remove all piercings and leave all jewelry and valuables at home.

CONTRAST MEDIA: Contrast may be indicated for your exam. The contrast media improves the radiologist’s ability to find structures that are abnormal and understand normal anatomy better.

• Some patients should not have an iodine-based contrast media. If you have problems with your kidney function, please inform your radiologist in advance. We may be able to perform the scan without the contrast media or find an alternate imaging exam.
• The most common type of CT scan with contrast is the double-contrast study, which will require you to drink a contrast media before your exam begins in addition to the IV contrast. The more contrast you are able to drink, the better the images are for the radiologist to visualize your digestive tract.

ALLERGY: Please inform the access center representative when you schedule your scan if you have had an allergic reaction to any contrast media. IV contrast will not be administered if you have had a severe or anaphylactic reaction to any contrast media in the past. Mild to moderate reactions warrant a plan that includes taking medication prior to the CT examination. These plans will be discussed with you in detail when you schedule your exam. Any known reactions to a contrast media should be discussed with your personal physician.

EAT/DRINK: If your study was ordered without contrast, you can eat, drink and take your prescribed medications prior to your exam.

If your doctor orders a CT scan with contrast, do not eat anything three hours prior to your CT scan. We encourage you to drink clear liquids. You may also take your prescribed medications prior to your exam.

DIABETICS: People with diabetes should eat a light breakfast or lunch three hours prior to the scan time. Depending on your oral medication for diabetes, you may be asked to discontinue use of the medication for 48 hours after the CT examination. Detailed instructions will be given following your examination.

MEDICATION: All patients can take their prescribed medications as usual.

The Newest CT: Faster Than a Heartbeat

A new CT scanner will change the management and outcomes of coronary artery disease. The CT scan captures images of the heart between beats, leading to clearer images to help detect anatomic and functional characteristics of coronary artery disease. This technology can also be used to help replace invasive tests to determine which patients with chest pain need intervention.

Read more

What are the risks of a CT scan?

If you are pregnant or think you may be pregnant, you should notify your health care provider.

The amount of radiation dose used in a CT scan is small. You may want to ask your doctor about the amount of radiation used during the CT procedure and the risks related to your particular situation.

If you are claustrophobic or tend to become anxious easily, tell your doctor ahead of time. You may be prescribed a mild sedative to take before the procedure to make you more comfortable.

What happens during a CT scan?

CT scans may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your physician’s practices. Generally, CT scans follow this process:

• You may be asked to change into a patient gown. If so, a gown will be provided for you. A locker will be provided to secure all personal belongings. Please remove all piercings and leave all jewelry and valuables at home.
• If you are to have a procedure done with contrast, an IV line will be started in the hand or arm for injection of the contrast media. For oral contrast, you will be given a liquid contrast preparation to swallow. In some situations, the contrast may be given rectally.
• You will lie on a scan table that slides into a large, circular opening of the scanning machine.
• The technologist will be in another room where the scanner controls are located. However, you will be in constant sight of the technologist through a window. Speakers inside the scanner will enable the technologist to communicate with and hear you. You may have a call button so that you can let the technologist know if you have any problems during the procedure. The technologist will be watching you at all times and will be in constant communication.
• As the scanner begins to rotate around you, X-rays will pass through the body for short amounts of time. You will hear clicking sounds, which are normal.
• The X-rays absorbed by the body’s tissues will be detected by the scanner and transmitted to the computer. The computer will transform the information into an image to be interpreted by the radiologist.
• It is important that you remain very still during the procedure. You may be asked to hold your breath at various times during the procedure.
• If contrast media is used for your procedure, you may feel some effects when the contrast is injected into the IV line. These effects include a flushing sensation, a salty or metallic taste in the mouth, a brief headache, or nausea and/or vomiting. These effects usually last for a few moments.
• You should notify the technologist if you have any breathing difficulties, sweating, numbness or heart palpitations.
• When the procedure has been completed, you will be removed from the scanner.
• If an IV line was inserted for contrast administration, the line will be removed.
• While the CT procedure itself causes no pain, having to lie still for the length of the procedure might cause some discomfort or pain, particularly in the case of a recent injury or invasive procedure, such as surgery. The technologist will use all possible comfort measures and complete the procedure as quickly as possible to minimize any discomfort or pain.

What happens after a CT scan?

• If contrast media was used during your procedure, you may be monitored for a period of time for any side effects or reactions to the contrast, such as itching, swelling, rash or difficulty breathing.
• If you notice any pain, redness and/or swelling at the IV site after you return home following your procedure, you should notify your doctor, as this could indicate an infection or other type of reaction.
• There is typically no special type of care required after a CT scan. You may resume your usual diet and activities unless your doctor advises you differently.
• Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.

What are some of the advances in CT technology?

Advances in CT technology include:

• High-resolution CT: This type of CT scan uses very thin slices (less than 0. 1 inches), which are effective in providing greater detail in certain conditions, such as lung disease.
• Helical or spiral CT: During this type of CT scan, both the patient and the X-ray beam move continuously, with the X-ray beam circling the patient. The images are obtained much more quickly than with standard CT scans. The resulting images have greater resolution and contrast, providing more detailed information. Multidetector-row helical CT scanners may be used to obtain information about calcium buildup inside the coronary arteries of the heart.
• Ultrafast CT (also called electron beam CT): This type of CT scan produces images very rapidly, thus creating a type of “movie” of moving parts of the body, such as the chambers and valves of the heart. This scan may also be used to obtain information about calcium buildup inside the coronary arteries of the heart, but the helical scanners are much more common.
• Computed tomographic angiography (CTA): Angiography (or arteriography) is an X-ray image of the blood vessels. A CT angiogram uses CT technology rather than standard X-rays or fluoroscopy to obtain images of blood vessels — for example, the coronary arteries of the heart.
• Combined positron emission tomography and CT (PET/CT): The combination of CT and positron emission tomography technologies into a single machine is referred to as PET/CT. PET/CT combines the ability of CT to provide detailed anatomy with that of PET to show cell function and metabolism in order to offer greater accuracy in the diagnosis and treatment of certain types of diseases, particularly cancer. PET/CT may also be used to evaluate conditions such as epilepsy, Alzheimer’s disease and coronary artery disease.

Purpose, Procedure, Risks, Side-Effects, Results

Written by WebMD Editorial Contributors

• How Do CT Scans Work?
• How Are CT Scans Done?
• What Is It Used For?
• What Is a CT Scan with Contrast?
• Are There Any Risks?
• What Are the Side Effects?
• More

A computed tomography (CT or CAT) scan allows doctors to see inside your body. It uses a combination of X-rays and a computer to create pictures of your organs, bones, and other tissues. It shows more detail than a regular X-ray.

You can get a CT scan on any part of your body. The procedure doesn’t take very long, and it’s painless.

They use a narrow X-ray beam that circles around one part of your body. This provides a series of images from many different angles. A computer uses this information to create a cross-sectional picture. Like one piece in a loaf of bread, this two-dimensional (2D) scan shows a “slice” of the inside of your body.

This process is repeated to produce a number of slices. The computer stacks these scans one on top of the other to create a detailed image of your organs, bones, or blood vessels. For example, a surgeon may use this type of scan to look at all sides of a tumor to prepare for an operation.

You’d probably get a scan at a hospital or radiology clinic. Your doctor might tell you not to eat or drink for a few hours before the procedure. You may also need to wear a hospital gown and remove any metal objects, such as jewelry.

A radiology technologist will perform the CT scan. During the test, you’ll lie on a table inside a large, doughnut-shaped CT machine. As the table slowly moves through the scanner, the X-rays rotate around your body. It’s normal to hear a whirring or buzzing noise. Movement can blur the image, so you’ll be asked to stay very still. You may need to hold your breath at times.

How long the scan takes will depend on what parts of your body are being scanned. It can take anywhere from a few minutes to a half-hour. In most cases, you’ll go home the same day.

Doctors order CT scans for a long list of reasons:

• CT scans can detect bone and joint problems, like complex bone fractures and tumors.
• If you have a condition like cancer, heart disease, emphysema, or liver masses, CT scans can spot it or help doctors see any changes.
• They show internal injuries and bleeding, such as those caused by a car accident.
• They can help locate a tumor, blood clot, excess fluid, or infection.
• Doctors use them to guide treatment plans and procedures, such as biopsies, surgeries, and radiation therapy.
• Doctors can compare CT scans to find out if certain treatments are working. For example, scans of a tumor over time can show whether it’s responding to chemotherapy or radiation.

In a CT scan, dense substances like bones are easy to see. But soft tissues don’t show up as well. They may look faint in the image. To help them appear clearly, you may need a special dye called a contrast material. They block the X-rays and appear white on the scan, highlighting blood vessels, organs, or other structures.

Contrast materials are usually made of iodine or barium sulfate. You might receive these drugs in one or more of three ways:

• Injection: The drugs are injected directly into a vein. This is done to help your blood vessels, urinary tract, liver, or gallbladder stand out in the image.
• Orally: Drinking a liquid with the contrast material can enhance scans of your digestive tract, the pathway of food through your body.
• Enema: If your intestines are being scanned, the contrast material can be inserted in your rectum.

After the CT scan, you’ll need to drink plenty of fluids to help your kidneys remove the contrast material from your body.

CT scans use X-rays, which produce ionizing radiation. Research shows that this kind of radiation may damage your DNA and lead to cancer. But the risk is still very small — your chances of developing a fatal cancer because of a CT scan are about 1 in 2,000.

But radiation’s effect adds up over your lifetime. So your risk increases with every CT scan you get. Talk to your doctor about the procedure’s potential dangers and benefits, and ask why the CT scan is necessary.

Ionizing radiation may be more harmful in children. That’s because they’re still growing. They also have more years to get exposed to radiation. Before the procedure, you may want to ask the doctor or technician if the CT machine’s settings have been adjusted for a child.

Tell your physician if you’re pregnant. If you need imaging for your stomach area, your doctor may recommend an exam that doesn’t use radiation, such as an ultrasound.

Some people are allergic to the contrast materials. Most of the time, the reaction is mild. It can lead to itchiness or a rash. In very few cases, the dye may trigger a life-threatening reaction. For this reason, your health care provider may want to monitor you for a short period after your CT scan. Tell your doctor about any allergies you have to medications, seafood, or iodine.

Your doctor should know, too, if you have diabetes and are taking the drug metformin. They’ll let you know if you should stop taking your medication before or after your procedure.

Although it’s rare, contrast materials can lead to kidney problems. Let your doctor know if you have any kidney issues before the CT scan.

Top Picks

Kinematic laser scanning for urban land use and utility infrastructure assessment

Urbanization and the development of megacities pose serious challenges for sustainable but efficient land use around the world. Power lines, pipelines for water, district heating, gas and oil, and other technological systems are critical but often hidden features that make modern life easier. Meanwhile, there is an ongoing need to preserve natural environments and recreational spaces in the world’s cities, despite the need to lay more concrete and asphalt to accommodate the people and businesses flocking to them. This article looks at how kinematic laser scanning can contribute to urban planning and infrastructure management.

The need for more efficient use of the limited urban area is constantly increasing. This is driving the development and use of 3D information systems, such as in cadastre, land-use planning and utility management, as well as in surveying and documentation technologies, to provide high quality 3D and graphical data to meet such needs. Knowing the exact location of infrastructure is important to ensure smooth operation so that you can plan and manage the construction of new pipelines, data cables, power cables, etc., as well as upgrade old systems and maintain and expand urban green spaces. If such data and information systems are accurate and up-to-date, all work can be completed faster, minimizing or eliminating unnecessary disruptions. At the same time, urban space can be used more efficiently to support various utilities, traffic and domestic needs.

Multi-modal (i. e., performed in multiple ways) laser scanning data is increasingly being used for surveying and cartography due to the development and availability of high-performance sensor technologies. Small but powerful laser scanning and imaging systems solve application problems using virtually any platform for laser scanning, from which data are subsequently solved for 3D reconstruction problems. Airborne kinematic laser scanning systems and devices on vehicles, backpacks and portable mapping systems can serve as a means of collecting additional data for various user needs and specifications.

3D point clouds provide a common starting point for automated modeling workflows and the creation of visualization and measurement applications, shaping the future topobase. They are an important asset for business and administration, especially in forestry, infrastructure management, and urban planning. They are also the basis for the development of solutions for future applied problems.

Calibration of a point cloud in an urban environment using a mobile laser scanning system to create a digital twin of the urban environment. In order to convert raw positioning and laser scan data into an accurate point cloud, it is necessary to calibrate the system offsets and sensor rotation axes – in this case, for this, planar elements are used that are automatically found in this survey area.

Kinematic laser scanning

Developments in laser scanning and point cloud processing can provide significant cost savings by automating the processing of data sets with improved output and detail. The collection of kinematic data is provided mainly by two different technologies: GNSS-IMU positioning and simultaneous localization and mapping (SLAM), both of which are means of tracking the movements of geodetic laser scanners during operation. The former provides data in the global geographic coordinate system, while the latter typically provides data in the local coordinate system.

What makes the use of laser scanning in mapping so effective is the ability to take 3D measurements of any object within the line of sight of the laser beam. To obtain information about the coordinates of reflections, the principles of laser ranging are used. The range measurement method consists in transmitting short but powerful laser pulses at high speed towards the subject and collecting the backscatter signal. The signal is then processed to detect objects at various distances within the beam illumination area. With the help of positioning on the trajectory, data synchronization and calibration of the aiming system, the received information is processed into usable three-dimensional data. An important end product of such surveys is a point cloud, where the location of each point is known in a local or geographic coordinate system. Such data enables instant visualization and measurement, but more often the user needs more generalized materials: virtual models and terrain models.

Drone data (suburban areas) can be used to assess land use and update urban planning and cadastre. High-resolution laser reflectance information provides insight into surface materials and helps to separate and identify objects.

Urban land use assessment

Urban land management is becoming increasingly important to ensure sustainable development and promote safe and prosperous communities and environments in ever-growing agglomerations and metropolitan areas. In general, the entire urban space can be divided into residential, business and public areas, transport facilities, parks, recreational and natural environment and communal facilities. All of this needs to be managed somehow.

Modern laser scanning technologies make it possible to map complex urban space in various ways, both from the air and from the ground. In general, airborne laser scanning, often supported by aerial photographs, is a versatile data source for large-scale terrain and building assessments. This allows a variety of tools to be used to detect new buildings and roads, monitor landfills, earthworks, illegal constructions, deforestation and other similar low-detail indicators, typically with an accuracy level of 10-50 cm.

Recreational space around an apartment building mapped using kinematic laser scanning. The data provide an accurate description of land use and construction sites. Dense point cloud data also enables fast visualization.

For more detailed control and especially for planning purposes, higher accuracy and resolution is desirable. For example, a more accurate estimate of backfill/excavation volume before a road or building is constructed can allow contractors to reduce costs, and even more so if they can track the progress of earthworks/excavations in near real time to control excavation and manage a truck fleet. It can also allow you to adjust the design of the final surface on the object after the end of construction (if necessary).

High-resolution laser scan data can be obtained from the air using unmanned aerial vehicles (UAVs or “drones”). Aerial scanning provides easy access to objects with obstacles such as fences, trenches and construction sites, and also allows you to take pictures of the condition of building roofs, power lines, and so on. Typically, instruments also provide more accurate measurements than those used at high altitudes, and data densities typically range from 50 to hundreds of points per square meter. Based on such data, various elements of the urban environment can be examined in detail: streets, curbs, ramps, outlines and heights of buildings, urban green spaces and soil cover, playgrounds, bridges and culverts, and much more.

3D kinematic data not only allows you to quickly document the construction phase, but also allows you to track land use, terrain and drainage height, as well as check the level of the building foundation and the placement of the structure against permits and the city plan.

Aerial (drone) survey data can be supplemented or replaced with ground survey data using Mobile Laser Scanning (MLS) systems. These systems can be moved using wheeled vehicles, and these data typically provide detailed mapping of street sections of interest. In some cases, smaller vehicles can be used to access restricted urban spaces. Alternatively, a backpack or portable tools can be used to obtain the data needed to complete the task at hand. Such data can typically cover interior areas, recreation areas, playgrounds, and parks, and provide a high level of detail in the mass of buildings, walkways, street layouts, and utilities.

Construction monitoring

Monitoring of construction activities is one of the key areas of interest for the city administration. Kinematic laser scanning data allows you to get a complete picture of the placement of the structure, the levels of the foundation, the location of the object in relation to the surrounding area, streets, and drainage systems.

From a builder’s and contractor’s perspective, laser scanning is an excellent tool for documenting construction progress and placing foundations or structural elements before moving on to the next phase of construction. Accurate data allows you to control the dimensions and adapt the design of prefabricated elements, which saves costs and minimizes delays.

From a safety and accessibility point of view, accurate 3D data allows you to plan and manage the use of space on a site to design areas for lifting, storage and movement. This data also makes it possible to document on-site protections such as fences and detours and traffic past the site. Such data can then be passed on to the city or road authority to report on work plans or potential impacts on traffic.

Earthworks and blasting at a construction site with a new building foundation.

Infrastructure documentation

Public and private infrastructure provides settlements with everyday resources (which are often taken for granted in urban life). These are electricity, water and heating, not to mention functional transport systems with roads, streets and related facilities. Maintaining this infrastructure to ensure its smooth operation requires effort and cost, which can be minimized through the use of modern asset management technologies. Up-to-date and accurate databases of 3D objects, supported by geodetic technologies that provide accurate 3D data, help prevent collateral damage during excavation and can be used to share asset information between contractors and other parties involved in any given construction.

Overhead cables are an important feature of any urban landscape as well as electric railways. They occupy space above urban areas, hang over streets and cut through parks and forests. Kinematic laser scanning is particularly suitable for corridor-type surveys, and power lines are well-defined corridor-type objects. Kinematic laser scanning provides ease of deployment and data collection with good accuracy and level of detail for modeling and monitoring of above ground objects. Mapping is not limited to the power line itself, but also provides accurate information about the terrain and vegetation in the immediate vicinity of the line. Off-road, mobile scanning in the desired corridor can be achieved by using all-terrain vehicles or by deploying a special laser scanning system in the form of a backpack with a laser scanner for work in difficult terrain. The main advantages of MLS (Mobile Laser Scanning) over Airborne Laser Scanning (ALS) are higher detail (due to less distance to objects of interest), less need for experienced maintenance personnel, and overall operability in difficult weather conditions (for example, in strong wind or rain).

Installation of underground pipeline for district heating. With kinematic laser scanning, the location of the containment box can be documented for future maintenance and repair planning.

Underground structures such as power cables, water and gas pipes, sewers, drainage pipelines, and district heating pipelines are usually laid underground to increase space efficiency, but often also to improve safety and ensure uninterrupted delivery. However, this poses a risk of damage and destruction if the exact location and depth of the installation is not well documented and new construction needs to be done in the area or, for example, there is a pipeline leak. Such documentation is possible using kinematic laser scanning, and the range of laser scanners does not require the imaging system to be located directly at the excavation zone, which increases the safety of the team and speeds up the process. In one pass, the surveyor can capture the laying object itself (cable, pipe), the surrounding earthworks and the general geometry of the objects of interest with a high degree of detail. Later, back at the office, the current status of the underground facilities, the location of the technical components and the main piping can be transferred to a database for distribution and future use. This application is often found in industrial facilities with complex piping and distribution installations.

A longitudinal section of the pipeline shows the location of the welds and seam insulation, the slope of the pipe and the position in depth relative to the earth backfill.

Output

The application of kinematic laser scanning in urban environments provides detailed information for many purposes related to the management, development and documentation of human activities and interactions with nature and terrain. The collection of kinematic data using laser scanning, whether based on GNSS-IMU or SLAM, allows you to quickly capture the geometry and condition of objects without disrupting operation, and captures precise dimensions and relationships between objects that are not always available using conventional surveying tools. With the help of kinematic laser scanning data, the actual state, construction phase and location of the components of the urban environment can be digitized, or the entire site can be surveyed and documented in 3D. Mapping and documenting the various uses of the urban environment, land cover, landscape features and vegetation are important applications for kinematic laser scanning in urban environments. This allows the use of these materials in the future for more rational planning of urban space and land use.

Railroad structures captured by a portable mobile system form the point cloud needed for asset documentation and modeling. The exact location of rails, supports, portals, wires and insulators, cable ducts and balancers is clearly visible, most objects are identified by an accurate point cloud.

High-resolution laser scanning data from aerial drone surveys of an urban area provide a detailed 3D picture of space usage and update the city plan.

Laser scanning for the preservation of cultural heritage sites and restoration work – Services on vc.ru

There is a huge number of cultural heritage sites. To preserve the appearance of the building, designers and architects must have detailed dimensional drawings of the object, including facades. The absence of a building project and facade drawings is a common situation that needs to be addressed.

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Thanks to 3D laser scanning, architectural measurements and modeling are faster, more accurate and more detailed than ever before. We are excited to bring these industry-changing services to today’s architects, led by a team that has extensive experience in laser scanning, modeling and data management.

Fig. 1 Digital 3d models of buildings on the street. Volkova Kazan

There is a practice of laser scanning of historical and cultural heritage sites for the purpose of preserving digital copies.

The major fire at Notre Dame Cathedral in Paris on April 15, 2019 affected people all over the world. Notre Dame has been documented inside and out using laser scanning to the nearest millimeter. Architectural historian Andrew Tallon, who died in 2018, scanned the cathedral in 2010. The cathedral has been scanned and over a billion data points have been collected, which are an exact 3d replica of the intact church. This data is used to restore the object.

Vladimir Serkov is a professional surveyor, entrepreneur and expert in the field of laser scanning, engaged in similar activities in Kazan.

“During my professional career, I voluntarily scanned several buildings in the city for the purpose of preserving digital copies of objects. The obtained data on laser scanning can be transferred to organize the Digital Archive of copies of buildings and for the purposes of teaching how to work with modern data. Further work on laser scanning of objects is planned”

Fig. 2 Digital 3d model of the building Kazan Family Center

Terrestrial laser scanning is a non-contact technology for determining the spatial coordinates of object surface points using a laser scanner. Due to its versatility and a high degree of automation of measurement processes, a laser scanner is not just a geodetic instrument, a laser scanner is a tool for quickly solving a wide range of applied engineering problems. That is why laser scanning has found its application in the construction industry. It is simply impossible to obtain such a volume of qualitative and quantitative information on a construction site by other methods.

Fig.3. Trimble laser scanner in operation Kazan

Fig. 4. Digital 3d models of buildings on the street. Gogol Kazan

In 2019, together with KSUAE teacher Irina Karpova and students-restorers, laser scanning of the “Officer’s House” of the Gunpowder Plant, located at ul.