Abstract
MATERIALS AND METHODS
Image datasets from the Adaptive 4DCBCT (ADAPT) clinical trial (ACTRN12618001440213), which included 30 patients treated for lung cancer, were analyzed. Two scan types were assessed: fast adaptive 4DCBCT (200 projections acquired over 20 breathing cycles, approximately 60-80s) and conventional 4DCBCT (1320 projections acquired over approximately 80 breathing cycles, 4 min). Two radiation oncologists and four radiation therapists, blinded to the image acquisition technique, independently rated the clinical utility of each scan using a two-question survey. Tumor visibility was rated on a three-point scale, and overall image quality was rated on a ten-point scale. A paired t-test was used to compare scores across acquisition techniques.
CONCLUSION
Fast adaptive 4DCBCT achieved similar image quality scores to conventional 4DCBCT while requiring only 15% of the imaging dose and 25% of the scan time. This study confirms the clinical feasibility of adaptive scanning protocols for use in radiation therapy for lung cancer.
RESULTS
Fast adaptive 4DCBCT showed a mean tumor visibility score of 2.3 ± 0.8, compared to conventional 4DCBCT (2.4 ± 0.7). For general image quality, fast adaptive 4DCBCT achieved a mean score of 4.1 ± 1.3, compared to conventional 4DCBCT, which had a mean score of 4.3 ± 1.2. There were no statistically significant differences in tumor visibility or image quality scores between fast adaptive 4DCBCT and conventional 4DCBCT scans.
BACKGROUND AND PURPOSE
Adaptive Four-Dimensional Cone-Beam Computed Tomography (4DCBCT) can reduce scan time and imaging dose in radiotherapy. This is achieved by modulating the projection acquisition rate and gantry rotation speed in response to real-time changes in patient breathing, together with motion-compensated image reconstruction. This study aimed to evaluate the clinical image quality of a fast adaptive 4DCBCT acquisition compared with conventional 4DCBCT in the treatment of lung cancer.