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A Comprehensive Dosimetric Evaluation and Performance Validation of the Newly Introduced HyperSight™ Cone-beam
N V N Madhusudhana Sresty1, T Anil Kumar1, V R P Lakshmi1
1Department of Radiotherapy, Basavatarakam Indo American Cancer Hospital and Research Institute, Hyderabad, Telangana, India.
Purpose:
Cone-beam computed tomography (CBCT) is integral to modern adaptive radiotherapy (ART) but is often limited by a small field of view, longer acquisition times, and inferior image quality compared with planning CT. Consequently, ART plan optimization and calculations are typically performed using synthetic CT. HyperSight™ is a recent technological advancement that addresses these limitations through a large-area detector, faster gantry rotation, and improved image quality. This system has been recently introduced in India, and this first Indian study represents the comprehensive, quality assurance (QA)-focused evaluation. In the second phase, its suitability for direct dose optimization and calculation was assessed using standard phantoms.
Materials And Methods:
The study was conducted on a Halcyon equipped with the HyperSight™ CBCT platform. Fan-beam scans were acquired using both big-bore and conventional CT systems. Standard QA tools, along with QUART and Catphan phantoms, were employed. X-ray tube performance tests, Image quality tests, Hounsfield units (HU) accuracy and constancy tests etc., were evaluated in accordance with national and international guidelines. VMAT plans were generated on different CBCT image sets of the phantoms.
Results:
Coefficient of variation in the X-ray output consistency was 0.0012. Slice thickness measured was within the tolerance. Hypersight CBCT proved its equality with CT in low contrast and high contrast resolution, uniformity and noise. HU accuracy and constancy closely matched the expected values in iterative CBCT (iCBCT) Accuros calculations. Target dosimetry between CT and iCBCT Accuros calculations were within 1% in Catphan and gamma analysis demonstrated excellent agreement.
Conclusions:
Overall, dosimetric accuracy and image quality confirm the superiority of this system for image-guided radiotherapy. Phantom results support ART workflows without intermediate steps; however, further clinical studies across treatment sites and improved scatter correction are required.
