What is the Difference Between a Cone Beam CT and a Regular CT scan

When it comes to medical imaging, CT (Computed Tomography) technology has revolutionised how we diagnose and treat various medical conditions. Two prominent types of CT scanning technologies – Cone Beam CT (CBCT) and conventional CT scans – serve different purposes in modern healthcare.

In this comprehensive guide, we’ll explore their differences, applications, and benefits to help you understand which technology might be more suitable for specific medical needs.

What is a CT scan?

The Computed Tomography scan is a widely recognised and commonly used imaging technique in healthcare. A regular CT scan utilises X-rays to create detailed cross-sectional images of the body.  

As the scanner rotates around the patient, X-ray beams capture images from multiple angles, which are then compiled by a computer to generate a series of slices or cross-sections of the body. This allows clinicians to examine internal structures layer by layer. 

CT scans are particularly effective in visualising complex structures within the body, such as: 

• Soft tissues (e.g., muscles, blood vessels, organs) 

• Bones 

• Blood clots and internal bleeding 

• Tumours and abnormalities 

Applications of CT scans

CT scans are known for their versatility and are frequently employed to diagnose a wide range of conditions, including cancers, cardiovascular diseases, and infections. They are used in emergency settings to quickly assess trauma patients, providing fast and clear images that help detect life-threatening conditions. 

What is a Cone Beam CT?

While the CT scan focuses on capturing detailed slices of larger body areas, CBCT is a specialised imaging technology primarily used in dental and maxillofacial imaging. Unlike the regular CT scan, CBCT uses a cone-shaped X-ray beam to capture the target area in a single rotation, creating a 3D image with remarkable detail. 

CBCT technology allows clinicians to capture fine details in smaller areas, such as: 

• Dental structures (teeth, roots, and jawbone) 

• Ear structures (ENT evaluations) 

• Orthopaedic assessments of extremities 

Applications of CBCT

Due to its ability to produce precise 3D images with lower radiation exposure, CBCT is highly valued in fields like: 

• Dentistry and orthodontics: For root canal evaluations, implant planning, and orthodontic assessments. 

• ENT (Ear, Nose, and Throat): For assessing sinus and ear structures. 

• Orthopaedics: For evaluating certain bones and joints, especially in the extremities. 

Key Differences Between CT and CBCT Scans 

Though both CT and CBCT scans utilise X-ray radiation, they differ fundamentally in their scanning mechanisms, image resolution, radiation levels, and clinical applications. Let’s examine these distinctions in more detail.  

1. Scanning Mechanism and Beam Shape

The primary technical difference between CT and CBCT scans lies in the beam shape and scanning mechanism: 

• CT scans: CT scans utilise a fan-shaped X-ray beam that moves in a spiral (or helical) motion around the body. This continuous rotation captures high-resolution images as the table on which the patient lies moves through the scanner. Multiple cross-sections are then compiled to produce 2D or 3D images. 

• CBCT Scans: In contrast, CBCT uses a cone-shaped beam that requires only a single rotation around the patient. This approach creates a 3D image with a lower radiation dose and faster capture time, making it ideal for focused imaging in areas such as the jaw or teeth. 

2. Resolution and Image Detail

Resolution differences are also notable: 

• CT scans: Known for high-resolution images that capture minute details, CT scans are suited for imaging complex structures, such as internal organs, blood vessels, and tumours. This makes CT ideal for diagnostic purposes requiring a high level of detail across varied body regions. 

• CBCT Scans: CBCT provides excellent detail, especially for smaller, high-density structures. However, its resolution is lower compared to that of a standard CT scan. CBCT’s strengths lie in producing clear images of bony structures rather than soft tissues, which is why it’s highly effective in fields like dentistry and maxillofacial imaging. 

3. Radiation Exposure and Patient Safety

When it comes to radiation exposure, safety is paramount in any imaging procedure. CT scans and CBCT differ significantly in this regard: 

• CT scans: To obtain high-resolution images, CT scans often require a higher dose of radiation. While they are safe for limited use, they may not be ideal for patients who need multiple scans or those particularly vulnerable to radiation exposure. 

• CBCT Scans: CBCT uses a lower radiation dose compared to traditional CT. This lower dose is advantageous for dental patients or those undergoing repeated scans in specific small regions, minimising long-term radiation risks. 

4. Clinical Applications and Use Cases

CT and CBCT scans serve distinct purposes within medical and dental settings: 

• CT scans: Broadly used across the medical field, CT scans are the preferred choice for diagnosing soft tissue injuries, head trauma, chest or abdominal pain, and bone fractures. Their high resolution and comprehensive imaging capabilities make them invaluable in emergency medicine, oncology, and cardiology. 

• CBCT Scans: CBCT is often the go-to technology for dental and ENT imaging due to its lower radiation, detailed 3D images, and ability to capture intricate bone structures. Dental professionals use CBCT for treatment planning in orthodontics, implantology, and maxillofacial surgery.

Advantages of CT scans

CT scans come with several distinct advantages: 

• High Resolution for Soft Tissues: With its ability to differentiate between soft tissues and organs, CT is ideal for viewing internal organs and diagnosing conditions like tumours or infections. 

• Fast and Effective in Emergencies: The spiral motion of a CT scan makes it quick and efficient, an essential quality in emergencies where rapid diagnostics are crucial. 

Advantages of CBCT Scans 

CBCT offers unique benefits that make it indispensable in dental and maxillofacial fields: 

• Lower Radiation Dose: Especially important for dental patients or children, the reduced radiation exposure of CBCT helps minimise risks associated with repeated imaging. 

• Precise 3D Imaging for Targeted Areas: CBCT is excellent for small, dense structures, allowing dentists and maxillofacial surgeons to visualise the jaw, teeth roots, and surrounding structures in 3D. 

Limitations of CT scans 

While CT scans are highly versatile, they also have limitations: 

• Higher Radiation Levels: Due to the fan-beam technology and high resolution, CT scans typically expose patients to more radiation, which may be concerning for patients needing multiple scans. 

• Less Detailed for Bone Structures in Dental Work: For dental evaluations, CT scans might lack the precision required for intricate bone structures and tooth root analyses. 

Limitations of CBCT Scans 

CBCT scans are also not without limitations: 

• Limited Use for Soft Tissue Imaging: CBCT’s lower resolution for soft tissues makes it unsuitable for general body scans or evaluating organs, where detailed soft tissue images are essential. 

• Restricted to Head and Neck Regions: Most CBCT scanners are designed specifically for head and neck imaging, making them less suitable for imaging larger body areas. 

Choosing Between CT and CBCT: What Matters Most 

Deciding between a CT and CBCT scan depends on the patient’s needs and the specific area requiring imaging: 

• CT scans are the preferred option for imaging larger body areas, particularly when a high-resolution view of soft tissues is needed. They’re ideal in emergency situations where fast and detailed images are critical for accurate diagnosis. 

• CBCT Scans are optimal for cases requiring 3D imaging of smaller, dense structures like teeth or the jaw. They provide excellent detail for planning dental implants, orthodontic assessments, and minor ENT-related procedures with a lower dose of radiation. 

When considering CT or CBCT scans, it’s always a good idea to consult with radiologists or imaging professionals. They can guide you on which scan is best suited for your needs, ensuring safe and effective imaging tailored to your medical requirements. 

How Can RIS Help? 

RIS is a leading provider of diagnostic imaging services in Australia, offering a comprehensive range of CT, CBCT, MRI, and other imaging modalities. Our team of highly qualified radiologists and technologists provide our patients with the most advanced and accurate imaging available.  

We are committed to patient safety and comfort, offering the latest technology in a welcoming and professional environment.

If you require any imaging solutions and are in Australia, please visit our website or contact us to schedule an appointment.