Medical imaging professionals use CT (Computerised Tomography) scanners to create cross-sectional images of the body. CT scanners accurately show what lies inside a patient’s body using a combination of X-ray technology and computer programs.
The device consists of a large hole or doughnut shaped structure called a gantry. The patient lies on a table that slides through the hole to get placed in the gantry. Once the patient is in the gantry, an X-ray tube rotates around the patient while detectors on the opposite side of the gantry measure the X-rays passing through the patient’s body.
There are many different types of CT scan machines, and they all vary depending on their application and technology. Some of the common types of CT scan machines include:
Conventional CT scans
One of the earliest forms of CT scanners were the traditional CT scanners, more popularly known as spiral or helical CT scanners. They produce a sequence of 2D images of the body through a narrow x-ray beam that is focused, which are then combined by a computer to generate an accurate 3D image. Fundamental features of the traditional CT scanners are:
Quick diagnosis in emergency cases is a need, for which traditional CT scanners are perfect. They are able to scan the entire body in a matter of seconds.
Traditional CT scanners are able to produce high-resolution images so that they can identify small lesions or abnormalities.
Patients undergoing traditional CT scans are allowed to move only slightly during the procedure so that images are not blurred.
Radiation exposure: Older CT scanners emit more radiation than newer versions, which can increase the risk of cancer development.
Limited ability to image certain body parts, such as the lungs and bones, using traditional CT scanners.
Cost-effective: Old-style CT scanners are often less expensive than newer scanners and thus are available to smaller hospitals and clinics.
Most clinics and hospitals have access to traditional CT scanners, which have made them a widespread device for the identification of various medical conditions.
Limited contrast resolution: Because traditional CT scanners have limited contrast resolution, it is difficult to differentiate among different types of soft tissues.
Spiral CT scans
To create precise 3D images of the body, spiral CT scans, which are otherwise known as helical CT scans, employ an advanced type of CT scanner that spirals continuously. With a spiral CT scanner, the scanner continuously spins around the patient, producing a continual flow of pictures that are combined to create a higher-quality 3D image of the body instead of taking separate “slices” of the body like with standard CT scans.
Spiral CT scanners can deliver images much quicker than conventional CT scanners and using less radiation on the patient while generating images of higher quality. They can be employed for more accurate imaging of organs such as the brain and other organs, and are particularly useful for imaging moving organs such as the heart and lungs.
Spiral CT scanners exist in two main forms: multi-slice and single-slice. Multi-slice scanners use multiple rows of detectors to generate better-quality images in a shorter time compared to single-slice scanners using a single row of detectors to create images.
Cancer, cardiovascular, and lung disease are just a few of the diseases most commonly diagnosed and followed up using spiral CT scans. They are also used to plan and guide a variety of medical procedures such as biopsies and radiation therapy.
Dual Energy CT Scanner
Dual-energy CT scanners, also known as spectral CT scanners, are a category of CT equipment that is capable of simultaneously capturing two sets of information at different energy levels. Therefore, the scanner can supply more accurate and detailed images by distinguishing between different kinds of tissue based on their density and composition.
Dual-energy CT scanners possess several major characteristics, including:
Dual-source CT: This scanner simultaneously acquires low- and high-energy information with two x-ray tubes and two detectors. Scanning times can be reduced, and image quality can be enhanced.
Single-source CT: This scanner switches between low- and high-energy scans with one x-ray tube and a specific filter. While it is slower to acquire the desired information, it is a less expensive option.
The capacity to visualize many substances and body structures, like the iodine in contrast agents or bone density, is referred to as spectral imaging.
Virtual non-contrast imaging: The ability can create a “virtual” non-contrast image based on dual-energy data without needing a true non-contrast scan. Besides enhancing patient comfort, this reduces radiation exposure.
Metal artefact reduction: Dual-energy CT scanners can reduce the artefact caused by metallic implants, like those in joint replacement or dental therapy. This allows the tissue around it to be visible more clearly.
Multi-Slice CT scanner
numerous rows of detectors: MSCT scanners have numerous rows of detectors, enabling them to capture more image data with every rotation of the X-ray tubes. Because of this, scan times can be reduced and 3D images created.
MSCT scanners are able to create images with a resolution of sub-millimeters, which enables them to capture extremely fine details in the body.
Lower radiation doses can be employed by MSCT scanners than older versions of CT scanners and still provide images of sufficient quality.
Dynamic scanning: Through quickly taking multiple photos during a single breath-hold, MSCT scanners are capable of imaging moving internal body structures such as the heart or lungs.
Dual-energy ability: Certain MSCT scanners can create images with multiple X-ray energies due to their dual-energy abilities. This can be useful for detecting certain tissue types, like calcium deposits or iodine contrast.
Cone-Beam CT Scanner
Technology: Cone-Beam CT is a refined version of standard CT scanning. The CBCT scanner employs a cone-shaped X-ray beam rotating around the patient rather than a fan-shaped X-ray beam to acquire a series of images and then combine them into a 3D patient volume.
Applications: CBCT scanners can be applied in various facilities such as orthopaedics, radiology, and interventional procedures. They are most commonly utilized in dentistry and maxillofacial imaging, though.
Benefits: CBCT scanners are better than other CT scanners in several aspects. They are faster in scanning and are able to produce 3D images of high quality with low exposure to radiation.
Cons: In contrast to traditional CT scanners, CBCT scanners also have a limited field of view, meaning they are only capable of capturing images of a small area of the body. Second, CBCT image resolution may not be as great as for traditional CT scans.
Some examples of CBCT scanners include the Vatech Pax-i3D Green, Planmeca ProMax 3D Mid, and Carestream CS 9300.
Photon- Counting CT Scanner
More advanced CT scanners referred to as photon-counting CT scanners (PCCT) incorporate advanced detector technology and improve image quality, reduce exposure to radiation, and allow for novel clinical applications.
The PCCT scanners incorporate photon-counting detectors (PCDs), which use the ability to measure the energy of individual x-ray photons to provide higher contrast resolution due to the ability to differentiate between tissues of varying densities and the measurement of the x-ray beam with higher accuracy.
CT scanning can be radically transformed by PCCT technology, particularly in cardiology, cancer, and neurology. PCCT would help in the detection of small lesions at an early stage and help to track disease development since it has the ability to accurately distinguish different tissue types.
By better delineating tumour borders and sparing normal tissue, PCCT would have a major impact on the accuracy of radiation therapy planning.
Portable CT Scanner
Rather than having the patient rolled to the machine, portable CT scanners are small devices that can be carried to the patient site. They are often used in emergency and critical care environments where rapid and easy imaging is needed, as well as in remote or resource-limited areas where a fixed CT scanner might not be present.
Some of the key features of CT scanners are
Lightweight design: Portable CT scanners are designed to be portable and lightweight, which makes it easy to transport them and have them ready in other locations.
Battery-powered: Because most portable CT scanners have batteries integrated into them, they can be operated in areas with no electric outlet available.
The service of rapid imaging can be provided by portable CT scanners with scan times ranging from a few minutes to a few seconds.
Head, chest, abdomen, and extremities are some of the regions of the body that can be imaged via portable CT scanners because they are highly flexible.
Low radiation exposure: Certain mobile CT scanners have the latest imaging technologies that are designed to minimize radiation exposure, and thus these are ideal for use with children and other radiation-vulnerable populations.
