Program Information
The Feasibility of Simultaneous CBCT, Spectral CT and SPECT Online Imaging Using a Novel Linac Gantry-Based On-Board Imager
H Wang*, Y Kuang , University of Nevada, Las Vegas, Las Vegas, NV
Presentations
TU-H-605-6 (Tuesday, August 1, 2017) 4:30 PM - 6:00 PM Room: 605
Purpose: To investigate the feasibility of a novel Linac gantry-based On-Board Imager (OBI) for routine CBCT, energy-resolving spectral CT and SPECT online imaging through outfitting an MV-beam Linac with a single kV-beam source and a single photon-counting detector panel sharing the same coordinate system and isocenter of the MV beam in the Linac.
Methods: A kV-beam source and a pixelated CZT detector panel, positioning orthogonally to the MV beam direction, were mounted to a Linac in the treatment room. The system performance was evaluated by phantoms using GATE Monte Carlo software. The spatial resolutions of SPECT and CT within a single OBI were estimated using a hot insert phantom and oversampling a tungsten wire. The concurrent differentiated imaging performance from the triple modalities was tested by a phantom with inserts filled with gadolinium (Gd), gold (Au), calcium (Ca), and radioactive ⁹⁹ᵐTc. Moreover, the dual-isotope SPECT imaging was also examined by a phantom with inserts filled with ⁹⁹ᵐTc and ¹²³I.
Results: The spatial resolutions of SPECT and CT imaging of the system were estimated to be 4.8 mm and 0.66 mm, respectively. In spectral CT images of the phantom with the four kinds of inserts, the Au and Gd inserts can be differentiated well from each other using both K-edge imaging and optimal image-based weighting imaging methods. The reconstructed distribution of radiation activity of ⁹⁹ᵐTc agreed well with the CBCT image of the phantom. The reconstructed distributions of two isotopes of ⁹⁹ᵐTc and ¹²³I can be separated clearly based on their different photon peaks of emitted gamma photons.
Conclusion: This study demonstrated a new OBI architecture by integrating triple modalities, CBCT, spectral CT and SPECT into Linacs, which would open multiple opportunities to be implemented in RT that could improve the accuracy of various aspects of the workflow in the future.
Funding Support, Disclosures, and Conflict of Interest: Funding Suppot: NIH/NIGMS P20GM103440; Disclosures and Conflict of Interest: None.
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