Fig 1.
A. the sensor attachment and the viewpoint of the observer B. axes for the accelerometer. ax,y is the acceleration measured by the accelerometer and θaccel is the rotational angle calculated from the accelerometer data. C. axes for the gyrosensor. rz is the angular velocity measured by the gyrosensor and θgyro is the rotational angle calculated from the gyrosensor data.
Fig 2.
Schematic diagram of the image orientation correction system.
rz is the angular velocity measured by the gyrosensor; ax,y is the acceleration measured by the accelerometer; θgyro and θaccel are the rotational angles calculated from the gyrosensor and accelerometer data, respectively; θKalman is the rotational angle after the Kalman filter; and θ postproc is the final rotational angle used for image rotation. Gyro., gyrosensor; Accel., accelerometer.
Fig 3.
Experimental design of the clinical utility test.
Participants reported numbers printed on papers at the left main, right main, and right upper bronchi of the airway model for both exams with and without using the image orientation correction system. The numbers inside the airway model were reset for each test. A, computer; B, charged-coupled device (CCD) camera; C, sensor; D, handle of the endoscope; and E, airway model with numbered papers at the left main, right main, and right upper bronchi.
Table 1.
Error of rotational angle with different combinations of sensors, connections, and processing.
Error was defined as the difference between the measured rotational angle and the optical rotational angle. RMS, root mean square; Kalman, Kalman filtering.
Fig 4.
Results of the measured and optical rotational angles from 25 to 30 seconds after beginning the experiments.
A, wired connection; B, wireless connection.
Fig 5.
Images before and after orientation correction in various clinical situations.
A. With flexible endoscopy, changing the direction requires axial rotation of the endoscope. The gravitational distortion due to the rotation can be corrected by the orientation correction system. The procedure is also easier because the direction of the endoscope tip coincides with the spatial orientation of the endoscopist. This image was captured using the orientation correction system used in this study. B. With ultrasound-guided catheter insertion, the image orientation correction system can help to match the spatial orientation of the image and the operator. This image was captured using the orientation correction system used in this study. C. With conventional transesophageal echocardiography, the direction of gravity is upward. Therefore, air bubbles come down from the top of the image. D. In colonoscopy, the location of the mass can be accurately described even when there is no structural landmark. The upper direction of the raw image is indicated by a thick white arrow and the direction of gravity is indicated by a dashed line.