The main objective of this study is to evaluate the dose efficiency of coronary CT angiography (CTA) using a photon counting detector CT (PCD-CT) with the dose efficiency of coronary CT angiography of prior CT generations. 100 patients with a clinical indication for coronary CT angiography will be prospectively enrolled and undergo coronary CTA on a PCD-CT. For comparison, a matched retrospective cohort of 100 patients will be created who had undergone on a prior scanner generation (retrospective cohort).

Inclusion Criteria:

• indication for coronary CTA confirmed by board-certified radiologist ('justified indication' according to German/European radiation protection law) AND
• patient (is able to give informed consent and) has given informed consent.

Exclusion Criteria:

• contraindications to (iodine based) iv contrast material: known allergy to iodine-based iv contrast, acute or high-grade chronic kidney insufficiency with an estimated glomerular filtration rate < 30 ml/min/1.73 m², latent or manifest hyperthyroidism
• known or suspected pregnancy
• lactating mothers

Patients who are at least 18 years of age with a clincially indication for a coronary CTA scan. Indication ('justified indication' according to German/European radiation protection law) must be confirmed by a board-certified radiologist.

We plan to share individual participant data upon request (pending final approval by the data protection officer of the university hospital).

Requests for sharing individual participant data will be considered at the time of publication of the first manuscript containing result data.

We plan to share data on request at this point in time.