Inclusion Criteria:  patient is referred for an unenhanced CT OR contrast-enhanced CT of the chest/thorax confirmed by a board-certified radiologist ('justifying indication' according to German/European radiation protection law) AND patient is at least 18 years of age AND patient (is able to give informed consent and) has given informed consent.  Exclusion Criteria:  high degree of medical urgency (i.e. patient cannot be consented for iv contrast according to routine procedures) known or suspected pregnancy, or lactating . contraindications for contrast agent (renal failure, allergy, hyperthyroidism)