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Session: Multi-Disciplinary General ePoster Viewing [Return to Session]

Clinical Detectability of MR Suitable Prostate Fiducial Markers Utilizing the TrueBeam Advanced Imaging Package During VMAT Prostate Treatment in Phantom

M Klem*, K Jones, J Turian, Rush University Medical Center, Chicago, IL


PO-GePV-M-163 (Sunday, 7/25/2021)   [Eastern Time (GMT-4)]

Purpose: We study the detection of MR suitable fiducial markers (FM) in an anthropomorphic phantom. We report the clinical detection rate, angular dependence, and optimized detection algorithm choice for fiducial marker tracking during VMAT prostate treatment on the Varian TrueBeam.

Methods: A Rando phantom, holding a beefsteak prostate phantom seeded with 1, Platinum-coil (0.35x10mm) and 2, Platinum-coil (0.35x20mm) FM’s, was used. The phantom received a (VMAT) treatment utilizing on-board kV imaging and our clinical FM SOP. In each image, the Varian software found and located each marker within a 3mm radius of its planned location. Treatment was repeated 22 times using all available marker detection settings (MDS), collecting 913 images.

Results: The “GoldSeed_1_3x3_3” MDS was optimal for identifying the platinum-coil (0.35x10mm) marker, finding it in 100% of the projection images. The platinum-coil (0.35x20mm) marker was much more robust to MDS selection, where eight different settings each identified the marker in 100% of the projection images. Little projection-angle dependence was observed, with an association only appearing when the worst performing MDS’s were selected. The mean and standard deviation of the distance from the recognized marker position to the expected position in the projection images was found to be 1.25mm and 0.2mm respectively for the (0.35x20mm) marker and 1.5mm and 1.2mm respectively for the (0.35x10mm) marker using optimized MDS’s.

Conclusion: The TrueBeam Advanced Imaging Package was used during a VMAT treatment of a prostate phantom housed in an anthropomorphic pelvis phantom. The clinical detectability of two MR suitable FM’s was assessed. The longer platinum markers show improved detectability. Currently, marker detection accuracy is being studied and will be compared to prior measurements of markers from the same and different vendors.

Funding Support, Disclosures, and Conflict of Interest: Financial support from IZI Medical Products, OWINGS MILLS, MARYLAND 21117



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