CTPA protocol optimisation audit: challenges of dose reduction with maintained image quality.

•DLP for CTPA examination was found high in a large teaching hospital.•We carried out a multiparametric multicentre analysis of patients undergone CTPA as well as experiments on phantom models.•We optimised scanner parameters based on the analysis done which led to a significant dose reduction.•Image quality, assessed independently by three cardiothoracic consultant radiologists, was maintained.