Seungryong Cho MS, Presenter: Nothing to Disclose

Dan Xia BS, Abstract Co-Author: Nothing to Disclose

Charles A. Pelizzari PhD, Abstract Co-Author: Research grant, Varian Medical Systems, Inc

Xiaochuan Pan PhD, Abstract Co-Author: Nothing to Disclose

The proposed reverse helical CBCT can considerably increase volume coverage than the current circular CBCT in IGRT. It, however, poses a significantly challenging image reconstruction task. In this work, we seek to develop and evaluate algorithms for accurate image reconstruction in reverse helical CBCT for IGRT.

Current on-board CBCT scanner on a modern radiation therapy unit uses only a circular scan, which cannot yield data sufficient for reconstructing accurate 3D images, and the reconstructible volume of which is limited by the size of the detector. Diagnostic CT employs the slip-ring technology to achieve a multiple-turn helical scanning configuration for reconstructing 3D volumetric images. The on-board imager, however, can only reverse its rotation after each turn. A reverse helical scanning configuration is, therefore, proposed in this work. Accurate algorithm for image reconstruction for this novel scanning configuration is also proposed. Numerical studies using different phantoms relevant to IGRT were conducted to validate and evaluate the proposed reverse helical configuration and reconstruction algorithm.

We have implemented the algorithm for reconstructing accurate 3D images from reverse helical cone-beam data, and have performed numerical studies to validate and evaluate the proposed algorithm. Shepp-Logan and other phantoms were successfully reconstructed from two-turn reverse helical cone-beam data by use of the proposed algorithm. Results of our numerical studies confirm that the reverse helical scanning configuration can yield sufficient data for accurate 3D reconstruction and that the proposed algorithm can reconstruct accurately 3D images from the reverse helical cone-beam data.

A reverse helical CBCT with the proposed reconstruction algorithm is promising in increasing the reconstructible volume of the image and in improving the accuracy of the image for IGRT.

Cone-beam computed tomography (CBCT) plays an important role in image-guided radiation therapy (IGRT). We investigate and develop an innovative, reverse helical CBCT to benefit IGRT in this work.

Cho, S, Xia, D, Pelizzari, C, Pan, X, Reverse Helical Cone-beam CT and Its Application to Image-guided Radiation Therapy.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5004738.html