A new statistical reconstruction method with rebinning as a technique for reducing the dose in CT scanners utilizing a flying focal spot.

BACKGROUND AND OBJECTIVE

In this paper, we present an original concept for image reconstruction in spiral CT scanners, incorporating Flying Focal Spot technology. The primary goal of this work is to explore the feasibility of using Model-Based Iterative Reconstruction methods for CT scanners with the Flying Focal Spot technique, aiming to reduce the X-ray dose absorbed by patients during examinations. The geometry of the projection lines in these scanners significantly impedes the use of traditional reconstruction methods, as well as the application of statistical approaches that rely on a discrete-to-discrete data model. This challenge is the primary motivation for our proposed reconstruction method, which is based on a rebinning strategy and a continuous-to-continuous data model.

METHODS

Experiments performed using artificial data revealed that, at different noise levels, our approach outperforms the traditional reference method in terms of objective measures of image quality. Similarly, for physical projections acquired from a commercial scanner, we conducted a comparative study of our method with a traditional filtration algorithm, using objective quality measures for quarter-dose projections. Finally, a practical assessment by a highly experienced radiologist was conducted to verify the usefulness of our innovative approach in reducing the dose absorbed by patients, supported by objective classification measures.

RESULTS

The experiments demonstrate that our approach addresses the drawbacks of traditional methods in terms of image quality and offers the potential to significantly reduce the X-ray dose required for completing examination procedures. Thanks to the statistical underpinnings of our approach, the X-ray dose absorbed by patients during examinations can be reduced by up to 75% compared to the full-dose procedure.

CONCLUSION

Our original method combines a rebinning strategy with a novel statistical iterative reconstruction procedure. This approach enables a significant reduction in the dose absorbed by patients. Additionally, our reconstruction algorithm is extremely fast, taking approximately 26 s for all operations on a mid-range GPU. This efficiency is primarily due to the implementation of an FFT algorithm during the most computationally demanding calculations (convolutions) involved in the iterative reconstruction procedure. This feature is particularly valuable in ambulatory diagnostics.