Fig. 3

a Retention Z-score for LR₁ in relation to age in patients with a perfectly normal PRMC test (this is defined as a normal PRMC test showing no signs of regional impaired clearance or slow clearance in any part of the lung in combination with no coughing or throat clearing during the 2-h PRMC test). Lower retention Z-scores represent better clearance. b Retention Z-score for LR₂ in relation to age in patients with a perfectly normal PRMC test. Lower retention Z-scores represent better clearance. c PI in relation to age in patients with a perfectly normal PRMC test. Higher PI represents more peripheral initial deposition of the radioaerosol