Boyeol Yoo, Presenter: Nothing to Disclose

Hyekyun Chung, Abstract Co-Author: Nothing to Disclose

Rizza Pua, Abstract Co-Author: Nothing to Disclose

Jin Sung Kim PHD, Abstract Co-Author: Nothing to Disclose

Seungryong Cho MS, Abstract Co-Author: Nothing to Disclose

To reduce imaging radiation dose in cone-beam CT through an intensity-weighted region-of-interest imaging technique for image-guided radiation therapy.

A copper filter was mounted in place of a bowtie filter on the X-ray tube unit of an on-board imager for CBCT scan to purposely generate two regions with different X-ray intensities, resulting in an inner ROI and outer ROI. Since a half-fan full-scan mode is widely used for most treatment sites due to its enlarged field-of-view (FOV), the filter design and a reconstruction algorithm were accordingly implemented in this study. A half-fan based rebinned backprojection-filtration algorithm was implemented and used for its potential robustness against data truncation in various ROI imaging situations. Both experimental and numerical studies were conducted to demonstrate the feasibility of our proposed approach. We applied a penalized-weighted least squares (PWLS) method to reduce noise in the projection data in the outer ROI. A film dosimetry was performed to compare relative dose quantitatively in the experimental study.

Radiation dose to the phantom was reduced up to more than 30% in the IWROI scan than in a conventional scan. The ratio of noise in the outer ROI to the inner ROI was 1.8, but it was decreased to 1.4 after denoising by using the PWLS algorithm.

A half-fan based IWROI CT imaging with a denoising algorithm can be useful for reduction of imaging radiation dose and successful registration in IGRT applications.

It may help reducing imaging radiation dose during image-guided radiation therapy

Yoo, B, Chung, H, Pua, R, Kim, J, Cho, S, Low-dose Intensity-weighted Region-of-Interest (ROI) CT Technique for Image-guided Radiation Therapy.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12026422.html