Intraoperative Cone-Beam CT Scanners: A Guide for Robotic Spine Surgeons

In the ever-evolving world of spine surgery, precision and real-time imaging have become paramount. The advent of intraoperative Cone-Beam CT (CBCT) scanners, particularly those integrated with robotic systems, has revolutionized the way surgeons approach complex spinal procedures. These advanced imaging technologies offer detailed 3D visualizations of the spine, helping surgeons navigate with greater accuracy, plan trajectories, and make adjustments in real-time. Among the most prominent CBCT systems used in spine surgery are the O-arm 2000 by Medtronic, Airo TruCT by Stryker, and LoopX by Brainlab. In this guide, we will explore these systems and their unique features, with a focus on their applications for robotic spine surgery.

O-arm 2000 (Medtronic)

The O-arm 2000 is one of the most widely used intraoperative imaging systems in spine surgery. It employs a flat-panel detector to produce high-resolution images, a major improvement over traditional fluoroscopy. This technology reduces image distortion and provides surgeons with clearer, more detailed visuals of the spine during procedures.

Key Features:

• Flat-Panel Detector: Unlike conventional fluoroscopes, the O-arm uses a flat-panel detector, which minimizes distortion and offers more accurate imaging.

• Field of View (FOV): The O-arm’s FOV can be adjusted between 20 cm and 40 cm. The smaller 20 cm view is typically used for cervical and thoracolumbar pedicle screw placements, while the 40 cm view is beneficial for S2 alar iliac screw and iliosacral screw insertion.

• Radiation Dose Management: The O-arm offers three settings for radiation dose—Low, Standard, and High—allowing surgeons to optimize radiation exposure according to the procedure's needs. Low Dose Mode, for example, reduces radiation by 50%, adhering to the “As Low As Reasonably Achievable” (ALARA) principle.

• Post-Processing: Post-processing technology enhances the image quality, providing ultra-high-resolution 30-inch images for more accurate visualization during surgery.

  

Applications in Spine Surgery: The O-arm 2000’s real-time 3D imaging capabilities allow for precise screw placement and other instrumentation guidance during surgery. It is particularly useful for spine surgeons performing robotic-assisted procedures, as it helps to verify anatomy and alignment before and after each step of the surgery.

The O-arm has 3 options for adjusting the radiation dose:

• The  Low Dose Mode reduces radiation by approximately 50% compared to standard mode. 

• This helps achieve As Low As Reasonably Achievable principle of radiation exposure.

• The Standard Mode is used as baseline for comparison with other modes, and the average radiation dose per vertebra: 601 cGy/cm².

• The High Dose Mode is reserved for cases requiring higher image quality.

Radiation Pattern:

• During image acquisition, the radiation spreads outward in the shape of a

• butterfly.

• Those directly in front or behind the gantry receive lower dose of radiation.

• During 2D image acquisition, we try to stay in the area of least radiation, directly behind the console.

• During the 3D scan, surgeons and OR Staff can stay outside the operating room.

Challenges:

• Obese Patients: One of the challenges with the O-arm system is obtaining clear images in patients with higher body mass indexes (BMI). Increased soft tissue can obscure the anatomy, necessitating higher radiation doses and longer scan times. Surgeons may also face equipment weight limitations in these cases.

  

• Patient Orientation: Proper patient positioning is critical to ensure optimal imaging. The O-arm offers four positioning options: prone, supine, left lateral, and right lateral. Incorrect positioning may lead to lateral inversion of images, complicating surgical navigation.

  

Airo TruCT (Stryker)

The Airo TruCT system, developed by Stryker, is mounted on rails and features an integrated operating table. This system is designed for intraoperative imaging, providing real-time 3D imaging to enhance surgical accuracy and precision.

Key Features:

• Rail-Mounted Design: Unlike the mobile O-arm, the Airo TruCT is fixed to rails, which ensures stable imaging during surgery without the need for repositioning the system.

• Real-Time 3D Imaging: The Airo TruCT enables surgeons to capture detailed 3D images during the procedure, allowing for precise visualization of the spine and any implanted devices.

• Space Efficiency: This rail-mounted system is designed to minimize space requirements, making it a suitable choice for operating rooms with limited floor space.

LoopX (Brainlab)

The LoopX system by Brainlab is another advanced intraoperative CBCT system that provides high-quality imaging during spinal surgeries. Its compact and flexible design makes it a versatile option for a wide range of spine procedures.

Key Features:

• Compact and Flexible: The LoopX system is designed for both mobile and fixed use, allowing surgeons to adapt the system to various operating room layouts.

• High-Resolution Imaging: Like the O-arm and Airo TruCT, the LoopX offers detailed, high-resolution 3D imaging that assists in precise surgical navigation.

• Streamlined Workflow: The LoopX integrates seamlessly with other surgical tools, improving workflow efficiency and reducing the need for multiple imaging modalities.

Conclusion

Intraoperative Cone-Beam CT scanners, including the O-arm 2000, Airo TruCT, and LoopX, have revolutionized spinal surgery by offering real-time, high-quality 3D imaging. These systems provide critical visual information that enhances surgical precision, improves patient safety, and allows for better decision-making during complex spinal procedures.