Ionizing radiation has a number of harmful effects in humans. The most important among these is the induction of cancer. It is assumed that damage to DNA in the nucleus of a single cell can induce cancer. Among the different types of lesions inducted, DNA double-strand breaks (DSBs) are considered to be the most relevant effects that can initiate carcinogenesis.

The investigators are already conducting several other studies to prospectively compare the inducted DSBs by coronary CT-angiography and conventional coronary angiography. Extending these examinations to investigate the induced DSBs by myocardial scintigraphy allows a comparison of all three relevant imaging methods of the heart that incorporate ionizing radiation.

To evaluate this, the investigators are planning to examine patients who are scheduled for a clinically indicated myocardial scintigraphy. These examinations are routinely done by the Department of Nuclear Medicine in either a 1-day or a 2-day protocol according to the diagnostic reference values of the Federal Department for Radiological Protection. Blood samples will be taken from these patients at predefined time steps before and after the examination and DNA double-strand breaks will be determined from these blood samples specifically considering the applied activity of the tracer and the exposition kinetics.

Inclusion Criteria:

• myocardial SPECT clinically indicated

Exclusion Criteria:

• acute leukaemia or lymphoma
• radiation or chemotherapy in the last 6 months
• x-ray or scintigraphy within the last 3 days
• age below 18 years
• eGFR of below 60 ml/min

Patients clinically indicated to undergo myocardial SPECT.