Schematic showing the contouring process and data transfer. Refer to Sec. 1.5 for details. Large arrows show progression of steps.
(Left) Coronal slice of CT image of the T-shaped phantom used to test the contouring accuracy. Endoscope positions of the test images are identified. (Middle) 3D rendering based on a CT image of the T-shaped tube phantom used to test the contouring accuracy. X-marks are visible at the T-position and along one of the short arms. The white outline on the X-mark positioned at the T-position was contoured in the TPS using the CT threshold value. (Right) Sample endoscope image of the X-mark taken from the Close position as described in the text.
Screen shot of contouring software. Lower left is endoscope image, lower right is rendered CT image from same camera position. Contour of features drawn in real endoscope image [black line with blue points; set of points (u,v) S ) has been transferred over to rendered (set of points (u,v)CT). The generated mesh within contour (green points) has been projected from a 2D perspective (u,v)CT Mesh onto a 3D perspective [(x, y, z)Mesh].
Orthogonal images from radiation treatment planning software showing 2D contour from Fig. 3 in red imported in the treatment planning software. High CT-contrast region is from the phantom lesion soaked in CT contrast agent. The contour from the TPS based on CT threshold value is in cyan.
Example of improved accuracy following image-based registration. Left: endoscopic image. Middle: virtual endoscopic image-based on em tracking alone. Right: virtual endoscopic image after image-based correction.
Endoscopic contours for three clinical cases. Cases are depicted horizontally with the real endoscopic image and contour on the right, followed by the virtual image plus contour, axial and sagittal images showing clinical GTV contoured in TPS (red) and endoscopic contours (green).
Comparison of contouring accuracy of X-shape.
Registration error (mm) for registration based on em tracking alone, image-based registration and employing perpendicular distance between rays.
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