Queen's University, Kingston, ON, Canada.
Int J Comput Assist Radiol Surg. 2010 Jul;5(4):385-91. doi: 10.1007/s11548-010-0415-x. Epub 2010 Apr 10.
Fluoroscopic C-arms are being incorporated in computer-assisted interventions in increasing number. For these applications to work, the relative poses of imaging must be known. To find the pose, tracking methods such as optical cameras, electromagnetic trackers, and radiographic fiducials have been used-all hampered by significant shortcomings.
We propose to recover the rotational pose of the C-arm using the angle-sensing ability of accelerometers, by exploiting the capability of the accelerometer to measure tilt angles. By affixing the accelerometer to a C-arm, the accelerometer tracks the C-arm pose during rotations of the C-arm. To demonstrate this concept, a C-arm analogue was constructed with a webcam device affixed to the C-arm model to mimic X-ray imaging. Then, measuring the offset between the accelerometer angle readings to the webcam pose angle, an angle correction equation (ACE) was created to properly tracking the C-arm rotational pose.
Several tests were performed on the webcam C-arm model using the ACEs to tracking the primary and secondary angle rotations of the model. We evaluated the capability of linear and polynomial ACEs to tracking the webcam C-arm pose angle for different rotational scenarios. The test results showed that the accelerometer could track the pose of the webcam C-arm model with an accuracy of less than 1.0 degree.
The accelerometer was successful in sensing the C-arm's rotation with clinically adequate accuracy in the C-arm webcam model.
越来越多的计算机辅助介入开始采用透视 C 臂。为了实现这些应用，必须了解成像的相对位置。为了找到位置，已经使用了诸如光学相机、电磁跟踪器和放射性基准标记等跟踪方法，但这些方法都受到明显的缺点的限制。
我们提出使用加速度计的角度感应能力来恢复 C 臂的旋转位置，利用加速度计测量倾斜角度的能力。通过将加速度计固定在 C 臂上，在 C 臂旋转过程中，加速度计跟踪 C 臂的位置。为了验证这一概念，我们构建了一个带有摄像头设备的 C 臂模拟装置，以模拟 X 射线成像。然后，通过测量加速度计角度读数与摄像头位置角度之间的偏移量，创建了一个角度校正方程（ACE），以正确跟踪 C 臂的旋转位置。
我们使用 ACE 对摄像头 C 臂模型进行了多次测试，以跟踪模型的主角度和次角度旋转。我们评估了线性和多项式 ACE 跟踪摄像头 C 臂位置角度的能力，用于不同的旋转场景。测试结果表明，加速度计可以跟踪摄像头 C 臂模型的位置，精度小于 1.0 度。
在 C 臂摄像头模型中，加速度计成功地以临床足够的精度感知 C 臂的旋转。
