The definition of gantry and O-ring rotation in the Vero4DRT. The Vero4DRT can separately rotate the gantry along an O-shaped guide-lane and the O-ring along its vertical axis.
Projection images under the condition of (a) overlapping of the gold markers and (b) a low intensity ratio of gold markers. The upper right image within (a) shows enlarged views of the overlapped gold markers. These images are displayed with the same window level and width. The gold markers were surrounded by white squares. The gold markers cannot be automatically detected under these conditions.
A schematic view for calculating the intensity ratio of a gold marker to its surroundings on a fluoroscopic image. The central position of the gold marker was detected automatically by utilizing its high contrast to its surroundings. The intensity ratio of the gold marker to its surroundings was calculated as I s/I m, where I m is the intensity of a pixel (x, y), which denotes the center position of the gold marker, and I s is the intensity of the pixel with the third lowest intensity acquired among the pixels located at positions (x ± 5, y ± 5), (x ± 5, y ∓ 5), (x, y ± 5), and (x ± 5, y).
The intensity ratio of the fiducial marker to its surroundings as the function of the WEPL. Negative strong correlation was observed between the WEPL and the intensity ratio (R = −0.88, p < 0.01, 95% confidence interval: −0.85 to −0.90).
The intra- and interfractional variations in the minimum intensity ratio of the gold marker for each patient.
Multiplanner reconstruction images obtained from CT images at the level presenting the maximum intra- and interfractional decreases in the intensity ratio of the gold marker. (a) 4D-CTEI and (b) 4D-CTEE from session 2 for patient 1, and 4D-CTEE from (c) session 1 and (d) session 2 for patient 4. The upper left images within (c) and (d) show enlarged views of the aortic calcification.
Fluoroscopic images acquired at the optimal monitoring angle for patient 10. The gold markers are surrounded by black squares. The minimum intensity ratios of gold markers were 2.97 and 2.49 on the right and left images, respectively.
The scout images at (a) session 1, (b) session 2, and (c) session 3 for patient 6. The stable gold markers are surrounded by white squares, and the dislocated gold marker is surrounded by a white circle. For this patient, the gold marker was displaced after the CTS date and dropped out during the course of treatment.
Patient characteristics and the number of implanted gold markers on the first day of treatment.
The optimal gantry and O-ring angles and the minimum intensity ratio that were estimated from the WEPLs during the course of treatment.
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