What component of the CT scan determines the amount of data used in reconstruction?

The correct choice refers to raw data, which is the foundational information collected during the CT scanning process. This raw data consists of unprocessed measurements taken by the CT scanner's detectors as it captures the X-ray attenuation profiles of the scanned object.

In CT imaging, the raw data includes the various attenuation values detected from each angle around the body, and it serves as the primary input for the reconstruction algorithms used to create the final images. These values are crucial because they contain all the necessary information regarding the density and structure of tissues, which are later processed to produce the diagnostic images that radiologists interpret.

Processed images and post-processed data sets are derived from this raw data, meaning they have undergone filtering, enhancement, or other manipulations. While these contribute to the visual quality and interpretability of the final images, they do not directly determine the initial data used for reconstruction. Beam attenuation factors relate more to the physics of how X-rays interact with different tissues rather than to the data handling aspect in the context of CT reconstruction. Thus, raw data is the correct answer, as it is essential in determining the information that will ultimately be available for image reconstruction.