Investigation of cone-beam CT image quality trade-off for image-guided radiation therapy Journal Article

Authors: Bian, J.; Sharp, G. C.; Park, Y. K.; Ouyang, J.; Bortfeld, T.; El Fakhri, G.
Article Title: Investigation of cone-beam CT image quality trade-off for image-guided radiation therapy
Abstract: It is well-known that projections acquired over an angular range slightly over 180 degrees (so-called short scan) are sufficient for fan-beam reconstruction. However, due to practical imaging conditions (projection data and reconstruction image discretization, physical factors, and data noise), the short-scan reconstructions may have different appearances and properties from the full-scan (scans over 360 degrees ) reconstructions. Nevertheless, short-scan configurations have been used in applications such as cone-beam CT (CBCT) for head-neck-cancer image-guided radiation therapy (IGRT) that only requires a small field of view due to the potential reduced imaging time and dose. In this work, we studied the image quality trade-off for full, short, and full/short scan configurations with both conventional filtered-backprojection (FBP) reconstruction and iterative reconstruction algorithms based on total-variation (TV) minimization for head-neck-cancer IGRT. Anthropomorphic and Catphan phantoms were scanned at different exposure levels with a clinical scanner used in IGRT. Both visualization- and numerical-metric-based evaluation studies were performed. The results indicate that the optimal exposure level and number of views are in the middle range for both FBP and TV-based iterative algorithms and the optimization is object-dependent and task-dependent. The optimal view numbers decrease with the total exposure levels for both FBP and TV-based algorithms. The results also indicate there are slight differences between FBP and TV-based iterative algorithms for the image quality trade-off: FBP seems to be more in favor of larger number of views while the TV-based algorithm is more robust to different data conditions (number of views and exposure levels) than the FBP algorithm. The studies can provide a general guideline for image-quality optimization for CBCT used in IGRT and other applications.
Journal Title: Physics in Medicine and Biology
Volume: 61
Issue: 9
ISSN: 1361-6560; 0031-9155
Publisher: Unknown  
Journal Place: England
Date Published: 2016
Start Page: 3317
End Page: 3346
Language: eng
Notes: JID: 0401220; 2016/04/01 [aheadofprint]; ppublish