Andrew M Davis1,2, Erik A Pearson1, Xiaochuan Pan3, Charles A Pelizzari1, Hania Al-Hallaq1. 1. Department of Radiation and Cellular Oncology, University of Chicago, Chicago. 2. Department of Biomedical Engineering, Johns Hopkins University, Baltimore. 3. Department of Radiology, University of Chicago, Chicago.
Abstract
BACKGROUND: Some patients cannot be imaged with cone-beam CT for image-guided radiation therapy because their size, pose, or fixation devices cause collisions with the machine. OBJECTIVE: To investigate imaging trajectories that avoid such collisions by using virtual isocenter and variable magnification during acquisition while yielding comparable image quality. METHODS: The machine components most likely to collide are the gantry and kV detector. A virtual isocenter trajectory continuously moves the patient during gantry rotation to maintain an increased separation between the two. With dynamic magnification, the kV detector is dynamically moved to increase clearance for an angular range around the potential collision point while acquiring sufficient data to maintain the field-of-view. Both strategies were used independently and jointly with the resultant image quality evaluated against the standard circular acquisition. RESULTS: Collision avoiding trajectories show comparable contrast and resolution to standard techniques. For an anthropomorphic phantom, the RMSE is <7×10- 4, multi-scale structural similarity index is >0.97, and visual image fidelity is >0.96 for all trajectories when compared to a standard circular scan. CONCLUSIONS: The proposed trajectories avoid machine-patient collisions while providing comparable image quality to the current standard thereby enabling CBCT imaging for patients that could not otherwise be scanned.
BACKGROUND: Some patients cannot be imaged with cone-beam CT for image-guided radiation therapy because their size, pose, or fixation devices cause collisions with the machine. OBJECTIVE: To investigate imaging trajectories that avoid such collisions by using virtual isocenter and variable magnification during acquisition while yielding comparable image quality. METHODS: The machine components most likely to collide are the gantry and kV detector. A virtual isocenter trajectory continuously moves the patient during gantry rotation to maintain an increased separation between the two. With dynamic magnification, the kV detector is dynamically moved to increase clearance for an angular range around the potential collision point while acquiring sufficient data to maintain the field-of-view. Both strategies were used independently and jointly with the resultant image quality evaluated against the standard circular acquisition. RESULTS: Collision avoiding trajectories show comparable contrast and resolution to standard techniques. For an anthropomorphic phantom, the RMSE is <7×10- 4, multi-scale structural similarity index is >0.97, and visual image fidelity is >0.96 for all trajectories when compared to a standard circular scan. CONCLUSIONS: The proposed trajectories avoid machine-patient collisions while providing comparable image quality to the current standard thereby enabling CBCT imaging for patients that could not otherwise be scanned.
Authors: Sepideh Hatamikia; Ander Biguri; Gernot Kronreif; Michael Figl; Tom Russ; Joachim Kettenbach; Martin Buschmann; Wolfgang Birkfellner Journal: PLoS One Date: 2021-02-09 Impact factor: 3.240
Authors: Hania A Al-Hallaq; Laura Cerviño; Alonso N Gutierrez; Amanda Havnen-Smith; Susan A Higgins; Malin Kügele; Laura Padilla; Todd Pawlicki; Nicholas Remmes; Koren Smith; Xiaoli Tang; Wolfgang A Tomé Journal: Med Phys Date: 2022-03-15 Impact factor: 4.506
Authors: Sepideh Hatamikia; Ander Biguri; Gernot Kronreif; Joachim Kettenbach; Tom Russ; Hugo Furtado; Lalith Kumar Shiyam Sundar; Martin Buschmann; Ewald Unger; Michael Figl; Dietmar Georg; Wolfgang Birkfellner Journal: Med Phys Date: 2020-08-29 Impact factor: 4.071