P008: The OPTICA (OPTImised CTPA In Pregnancy) study: rationale and design of a prospective trial assessing the quality and safety of an optimised CTPA protocol in pregnancy. Issue 175 (March 2019) - Gillespie, C.D.; Foley, S.; Ewins, K.; Rowan, M.; NiAinle, F.; MacMahon, P.J.