In 2006, more than 30000 percutaneous coronary interventions (PCIs) were performed in Taiwan, In the past decade, improvement of PCI technology and radiography equipment have resulted lower pocedure time and radiation dose. But the patients' weight, the experience of the operator and the complexity of the procedure still possible make the dose higher. The knowledge of radiation dose maybe help the cardiologists to implement radiation sparing procedure eventually minimizing patients and operators radiation hazards in interventional cardiology.