Primum Non Nocere (First Do No Harm): The Safe and Efficient Performance of Cardiac Imaging The application of strong magnetic fields and radiation requires optimal technique applications. Abada and colleagues [1] offer reduced cardiac CT angiography (CTA) patient radiation dose by applying an automatic modulation technique (ECG-pulsed tube current modulation) at a reduced kilovoltage setting (80 kV) for coronary CT. Radiation dose exposure can be reduced by up to 88% for slim patients without impairing image quality. Abada et al. estimate that this ECG-pulsed tube current modulation technique produces a reduced radiation exposure of 2 mSV, which is similar to or less than that of conventional coronary angiography [2]. Cardiac imagers administer a variety of pharmacologic interventional agents before and during imaging. These range from the harmless radiopharmaceuticals and gadolinium chelates to the tricky but relatively safe βblockers, dipyridamole, adenosine, and nitroglycerine, and to the more challenging dobutamine. In spite of all of the potential side effects of these agents, the most treacherous cardiac imaging intervention—the iodinated contrast agent—is well known to radiologists. Just as radiologists have developed a relative comfort level with iodinated contrast agents, so must we learn to work with adenosine and β-blockers [3]. Pannu et al. [4] tell us how radiologists can implement a protocol so that β−blockers can be safely given, orally or IV, to most patients to lower the heart rate for cardiac CT. Patients can be screened for certain contraindications: heart rate less than 60 bpm, systolic blood pressure less than 100 mm Hg, decompensated cardiac failure, allergy to β-blockers, asthma or chronic obstructive pulmonary disease (COPD) using a β2-agonist inhaler, active bronchospasm, and secondor third-degree atrioventricular block. Perhaps the authors might have added a potential option for patients with COPD, active bronchospasm, or β-blocker allergy: 60–90 mg of diltiazem orally 1 hour before scanning can be a safe and efficacious alternative to βblockers [5]. Pannu et al. go on to add [4]: