SU‐CC‐ValA‐10: Cone‐Beam CT for Radiation Therapy with Reverse Helical Trajectory

Purpose: To propose and study a novel scanning trajectory, named reverse helical trajectory, for a cone‐beam CT (CBCT) imager mounted on a linear accelerator (LINAC) treatment system by applying an exact 3D backprojection filtration (BPF) algorithm. Method and Materials: A numerical study using 3D S...

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Bibliographic Details
Published in:Medical Physics 2006-06, Vol.33 (6), p.1984-1984
Main Authors: Cho, S, Pelizzari, C, Pan, X
Format: Article
Language:English
Subjects:
Computed tomography
Cone beam computed tomography
Image reconstruction
Linear accelerators
Medical image reconstruction
Medical imaging
Numerical modeling
Radiation therapy
Radiation treatment
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Summary:Purpose: To propose and study a novel scanning trajectory, named reverse helical trajectory, for a cone‐beam CT (CBCT) imager mounted on a linear accelerator (LINAC) treatment system by applying an exact 3D backprojection filtration (BPF) algorithm. Method and Materials: A numerical study using 3D Shepp‐Logan phantom was performed. We applied the PI‐line‐based BPF algorithm to reconstruct exact 3D image from data acquired numerically for a reverse helical trajectory. It was revealed that there is a middle gap in the reconstructed image which is due to lack of PI‐lines passing through the gap. Application of a chord‐based BPF algorithm showed a reduction in the middle gap. Two kinds of line plus reverse helical trajectories were proposed and tested to reduce the middle gap further. One of them is a reverse helical trajectory with a short line segment between two helices separated apart. The other one is a reverse helical trajectory with a long line segment connecting the end points of the revere helices. Results: The middle gap in the reconstructed image was reduced by employing a chord‐based BPF algorithm. The gap was reduced further when we modified the scanning trajectory by inserting a line segment between two helices. The gap was removed completely when we used a reverse helical trajectory with a long line segment connecting the end points of the revere helices. Conclusion: A novel scanning geometry for a LINAC‐mounted CBCT imager was proposed, and a preliminary numerical study was performed. The middle gap in the reconstructed image obtained by PI‐line‐based BPF algorithm was effectively eliminated by using a chord‐based BPF algorithm with a line plus reverse helical trajectory.
ISSN:0094-2405
2473-4209
DOI:10.1118/1.2240128