Iterative reconstruction is a computational imaging technique used in medical imaging, particularly in computed tomography (CT) and positron emission tomography (PET) scans. It involves using mathematical algorithms to reconstruct detailed, high-quality images from a series of low-dose or noisy data acquired during the scanning process. Iterative reconstruction algorithms iteratively process the data and refine the image reconstruction with each iteration, leading to improved image resolution, reduced image noise, and lower radiation dose to the patient. This technique allows for better image quality and more accurate diagnosis, while also reducing the potential risks associated with repeated exposure to radiation.