Optimization of MV-kV dual-energy CT imaging for tomographic therapy

Giavanna Jadick; Patrick La Rivière

doi:10.1117/12.2653674

7 April 2023 Optimization of MV-kV dual-energy CT imaging for tomographic therapy

Proceedings Volume 12463, Medical Imaging 2023: Physics of Medical Imaging; 124632L (2023) https://doi.org/10.1117/12.2653674
Event: SPIE Medical Imaging, 2023, San Diego, California, United States

Conference Poster

Abstract

Computed tomography (CT) imaging is a key element of effective radiation therapy treatment, providing a threedimensional patient model for treatment planning dose calculations and precise patient positioning at the time of treatment. For radiotherapy, CT images are acquired using either an additional kilovoltage (kV) x-ray source mounted onto the treatment system or the system’s intrinsic megavoltage (MV) source. With beam geometry similar to fan-beam CT, tomographic therapy systems have unique potential for performing MV-kV dual-energy CT (DECT) imaging. This work was undertaken to quantify the prospects of MV-kV DECT. Six MV-kV and three kV-kV spectral combinations were considered. Single ray signal-to-noise ratios (SNRs) were calculated for a two-material object using estimation theory in the context of basis-material decomposition. Maximum-achievable SNR and optimal dose allocation were compared across spectral combinations and object thicknesses. Basis material images of the XCAT phantom were simulated using 140kV-80kV and DetunedMV-80kV spectral pairs, using both optimized and equal dose distributions. Results demonstrated that optimal SNR is achieved with >80% dose allocated to the MV spectrum (1-cm bone, 40-cm tissue object). SNR improved by as much as 31.5% by optimizing the dose allocation. This yielded 26% noise reduction and 23% SNR improvement in the XCAT basis material images. Peak SNR and optimal dose distribution varied considerably for different object thicknesses, suggesting MV-kV DECT protocol should be carefully chosen for a given imaging task. This study demonstrates the potential for enhanced contrast with MV-kV DECT imaging and warrants further investigation into its practical implementation in radiotherapy settings.

Citation Download Citation

Giavanna Jadick and Patrick La Rivière "Optimization of MV-kV dual-energy CT imaging for tomographic therapy", Proc. SPIE 12463, Medical Imaging 2023: Physics of Medical Imaging, 124632L (7 April 2023); https://doi.org/10.1117/12.2653674

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