Schematic diagram of the Vero4DRT.
Schematic diagram of IRmarker-based dynamic tumor-tracking irradiation (IR tracking). In the 4D-modeling phase, the mean and standard deviation of the absolute 4D-modeling error, as well as the peak-to-peak amplitude of the target motion, are shown on the screen of the Vero4DRT. The right four groups of waves, from top to bottom, show variations in the IR markers’ positions in the AP direction and the target positions in the LR, CC, and AP directions, respectively. In the graphs of the target position, dark-colored waves show the detected target position and light-colored waves show the predicted target position. During beam delivery, the future 3D target position is calculated from the displacements of the IR markers using the 4D model, and then the corresponding tracking orientation is transferred continuously to the gimbaled x-ray head.
Photograph of the experimental system for (a) dosimetric and positional verification of IR marker-based dynamic tumor-tracking (IR tracking) of 1D sinusoidal patterns, (b) positional verification of 1D phase-shifted sinusoidal patterns, and (c) positional verification of the 3D respiratory patterns of six patients with lung cancer.
(a) Dose profile of a 50 × 50 mm2 field under stationary, tracking, and nontracking states and (b) variations in the tracked and measured positions of the target for the sinusoidal pattern with a peak-to-peak amplitude of 40 mm and breathing period of 2 s.
Variations in the target position along the CC direction for the respiratory pattern of the first patient who underwent IR tracking (Patient no. 3). Square symbols indicate the detected positions of the target, solid lines with round symbols indicate the tracked positions of the target, and dotted lines show positional tracking errors.
Accumulated probability histogram (a) as a function of the 95th percentile of the positional tracking error ( ) and (b) as a function of the tracking efficiency, defined as the ratio of twice the 95th percentile of the positional tracking error ( ) to the peak-to-peak amplitude (A), in the LR, CC, and AP directions under gantry angles of 0° (G0deg) and 90° (G90deg).
, , and under nontracking and tracking states for sinusoidal patterns.
, , and of phase-shifted sinusoidal patterns with a peak-to-peak amplitude of 20 mm and breathing period of 4 s.
, , and of respiratory patterns.
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