This retrospective study evaluated whether combining automated tube voltage selection (ATVS) with personalized contrast injection (P3T software) can optimize coronary CT angiography (CCTA) protocols while preserving diagnostic image quality. A total of 378 patients undergoing CCTA were grouped according to tube voltage (70, 80 or 90 kV) and acquisition mode (sequential or spiral). Radiation dose, contrast medium volume, and objective and subjective image quality were assessed. Signal-to-noise ratio was comparable across groups, with only minor differences in subjective image quality. Higher body weight was associated with higher tube voltage, contrast medium volume, and radiation dose. At the same tube voltage, sequential scanning resulted in lower radiation exposure than spiral scanning. Overall, combining ATVS and P3T enables patient-specific CCTA protocols while maintaining adequate diagnostic image quality and optimizing radiation and contrast doses.