filtered back projection
Classical CT reconstruction algorithm — analytic single-pass method that filters projection data and back-projects to form the image. The reference reconstruction method for decades; superseded as the clinical default by iterative reconstruction in the mid-2010s and now by deep-learning recon.
Why it matters to buyers: Legacy systems run FBP only. Iterative reconstruction is the upgrade path for dose reduction — a CT without IR / DL licensing runs at the older platform's dose / image-quality curve regardless of chassis age.
Why it matters to engineers: Fast (single-pass) but noisier than IR at equivalent dose. Still used as the reference recon for QA / commissioning measurements (CTDI, DLP) where the underlying physics rather than vendor-specific noise reduction is the relevant metric.