Fig. 4: The evaluation of PIDA as a fiducial marker in robotic SBRT.

a Schematic diagram of robotic SBRT in a clinical setting. b Pictures of the puncture needles (Scale bars: 1 cm), the PIDA marker (Scale bars: 1 mm), and the Au marker used in clinic (Scale bars: 1 mm). c MR image of a rat implanted with an Au marker on Day 7 post the implantation. d Optical image of the resected rat liver tissue containing the Au marker, in which severe edema was observed (yellow arrows). Scale bar: 0.5 cm. e MR image of a rat implanted with a PIDA marker on Day 7 post the implantation. f Optical image of the resected rat liver tissue containing the PIDA marker. Scale bar: 0.5 cm. g CT image of the Beagle implanted with a PIDA marker. White rectangle: PIDA in the Beagle liver; Bottom inset: The Beagle fixed in a memory cushion for SBRT. h Three-dimensional distribution map of planned X-ray radiation for RRT on the Beagle. i X-ray images of the Beagle liver at different phases during the respiratory cycle. Green circles: the positions of the PIDA marker on live X-ray images; Yellow diamonds: the original position of the PIDA marker on the X-ray image simulated from preoperative CT modeling. j Beagle’s respiratory movement during RRT determined by an optical respiratory tracking system. k Plot of the real-time correlation error during RRT. Blue dashed line indicates the threshold limit in clinic. l Plot of the real-time uncertainty during RRT. Red dashed line indicates the threshold limit in clinic. Source data are provided as a Source Data file.