Program Information
Development of Direct Triple On-Board Imaging in a Small-Animal Radiation Therapy Platform
H Wang*, Y Kuang , University of Nevada, Las Vegas, Las Vegas, NV
Presentations
MO-DE-605-2 (Monday, July 31, 2017) 1:45 PM - 3:45 PM Room: 605
Purpose: To demonstrate the feasibility of using a single pixelated semiconductor imager to realize triple on-board imaging including routine CBCT, energy-resolving spectral CT and SPECT in a small-animal radiation therapy (SART) platform.
Methods: The SART platform with the capability of on-board triple-modality image guidance was designed using Gate Monte Carlo software. A single energy x-ray tube was used both for imaging at a low tube current and for radiation therapy purpose at a high tube current. A single photon-counting CZT imager was used to detect both x-ray photons and gamma photons for reconstruction of spectral-CT/CBCT and SPECT images of small animals, respectively. The imaging performance of the designed system was evaluated with different phantoms. A PMMA phantom with iodine (I), gadolinium (Gd), and isotope ⁹⁹ᵐTc inserts was mainly used. To reconstruct spectral CT images, the K-edge imaging and the optimal image-based weighting imaging methods were used to achieve contrast element differentiation and mono-energetic decomposition.
Results: The intrinsic spatial resolution of the pixelated CZT imager was measured to be 8.6 lp/mm at 10% modulation transfer function (MTF). The spatial resolution of CBCT and SPECT imaging of the system was estimated to be 4.5 lp/mm at 10% MTF and 1.2 mm, respectively. The I and Gd inserts were clearly differentiated from each other in the reconstructed spectral CT images of the PMMA phantom. The reconstructed radioactivity distribution of the isotope ⁹⁹ᵐTc in the phantom agreed well with the actual inserts, which can be seen from the fused SPECT/CBCT image of the phantom.
Conclusion: This study investigated a novel SART platform with high-quality on-board SPECT/spectral-CT/CT imaging of small animals, which provides comprehensive anatomical, functional and molecular image guidance for radiation beam delivery. The architecture investigated could also shed lights on the routine procedure of RT, from dose calculation, organ characterization, to IGRT process.
Funding Support, Disclosures, and Conflict of Interest: Funding Suppot: NIH/NIGMS P20GM103440; Disclosures and Conflict of Interest: None.
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