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Proceedings Paper

Metal artifact suppression in megavoltage computed tomography
Author(s): L. John Schreiner; Myron Rogers; Greg Salomons; Andrew Kerr
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Paper Abstract

There has been considerable interest in megavoltage CT (MVCT) imaging associated with the development of image guided radiation therapy. It is clear that MVCT can provide good image quality for patient setup verification with soft tissue contrast much better than noted in conventional megavoltage portal imaging. In addition, it has been observed that MVCT images exhibit considerably reduced artifacts surrounding metal implants (e.g., surgical clips, hip implants, dental fillings) compared to conventional diagnostic CT images (kVCT). When encountered, these artifacts greatly limit the usefulness of kVCT images, and a variety of solutions have been proposed to remove the artifacts, but these have met with only partial success. In this paper, we investigate the potential for CT imaging in regions surrounding metal implants using high-energy photons from a Cobalt-60 source and from a 4 MV linear accelerator. MVCT and kVCT images of contrast phantoms and a phantom containing a hip prosthesis are compared and analysed. We show that MVCT scans provide good fidelity for CT number quantification in the high-density regions of the images, and in the regions immediately adjacent to the metal implants. They also provide structural details within the high-density inserts and implants. Calculations will show that practical clinical MVCT imaging, able to detect 3% contrast objects, should be achievable with doses of about 2.5cGy. This suggests that MVCT not only has a role in radiotherapy treatment planning and guidance, but may also be indicated for surgical guidance and follow-up in regions where metal implants cannot be avoided.

Paper Details

Date Published: 20 April 2005
PDF: 9 pages
Proc. SPIE 5745, Medical Imaging 2005: Physics of Medical Imaging, (20 April 2005); doi: 10.1117/12.596020
Show Author Affiliations
L. John Schreiner, Cancer Ctr. of Southeastern Ontario (Canada)
Queen's Univ. (Canada)
Myron Rogers, Cancer Ctr. of Southeastern Ontario (Canada)
Greg Salomons, Cancer Ctr. of Southeastern Ontario (Canada)
Queen's Univ. (Canada)
Andrew Kerr, Cancer Ctr. of Southeastern Ontario (Canada)
Queen's Univ. (Canada)

Published in SPIE Proceedings Vol. 5745:
Medical Imaging 2005: Physics of Medical Imaging
Michael J. Flynn, Editor(s)

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