Program Information
Investigational Study of a Dynamic Dual-Layer Flat Panel Detector Prototype for Soft Tissue Motion Tracking
M Lu*, J Steiger , R Aufrichtig , PerkinElmer Medical Imaging, Santa Clara, CA
Presentations
WE-AB-601-8 (Wednesday, August 2, 2017) 7:30 AM - 9:30 AM Room: 601
Purpose: : A dual-layer dynamic flat panel detector (FPD) prototype is investigated for its potential use in a real-time soft tissue motion tracking application for radiotherapy.
Methods: A chest phantom is imaged to investigate the feasibility of using a dual-layered dynamic a-Si FPD prototype for real time soft tissue motion tracking. The chest phantom incorporates lung-equivalent nylon nodules, 10mm in diameter and 5-15mm in thickness. To simulate ribs, two 3mm and 6mm thick aluminum bars cover the lung nodules. The chest phantom is positioned on a rotating table spinning at 5 degree per second to simulate nodule motion. The FPD prototype is built using a PerkinElmer XRD 4343RF detector by adding a second (top) a-Si panel, which is separated from the bottom panel by a 1mm copper filter. The top and bottom layers are optimized by changing scintillator thicknesses and gain settings for various X-ray exposures. More than 300 frames are acquired at 15 fps at 300µm pixel resolution.
Results: Image registration is performed to ensure alignment of the low and high energy image sequences from the top and bottom layers, respectively. Soft-tissue only images are created by removing the aluminum bars with a weighted log subtraction technique. Soft tissue motion is tracked through a full rotation cycle. The tracking error is estimated to be 1.6pixels or 0.5mm (1 standard deviation).
Conclusion: The feasibility of using a dual-layer dynamic FPD for soft tissue motion tracking is investigated. The study indicates that a soft tissue motion tracking accuracy of less than 1mm can be achieved, even in the presence of bony structures. Further investigation will be performed with an improved detector prototype and a more realistic lung motion phantom.
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