Which process involves projecting ray sum data back onto a matrix in iterative reconstruction algorithms?

Back projection is a fundamental process used in iterative reconstruction algorithms in computed tomography (CT). In this process, the raw data collected from the detector after the X-ray beams have passed through the patient is mathematically projected back onto a two-dimensional matrix. This step is essential in forming an initial image reconstruction.

The term refers to the method of taking the ray sum data collected during the scan and spreading it back across the pixel grid, effectively reversing the initial projection of the data. This initial back projection creates a basic representation of the image, which can then undergo additional processing and refinement through iterative algorithms to improve image quality, reduce noise, and enhance contrast.

Iterative reconstruction utilizes this back projection technique combined with repeated cycles of image adjustments, allowing for a more accurate final image. This process ultimately helps in reducing artifacts and improving diagnostic quality while allowing for lower doses of radiation compared to traditional reconstruction methods.