Catalan to English Medical Medical (general) Radiology

This is from a medical report in Catalan, directly under the heading "Procediments" it says "RX TÒRAX 1-2 PROJECCIONS (F I P)". The patient has a cough resulting from virosis with respiratory superinfection.

I know it's "CHEST X-RAY with 1–2 PROJECTIONS" but I can't find what F I P (probably F y P in Spanish) is.

It's listed on price lists and medical code guides (e.g., http://80.33.165.27/DemoECAP/umi_1/sisap-umi.eines.portalics... but I've not been able to identify the meaning anywhere.

I did find "Front & Inverted Posterior" i.e. posteroanterior (PA) and lateral, which could be something like "frontal i posterior invertit" but it doesn't feel right.

Does anyone know?