Methods and software for self-gating a set of images. In exemplary embodiments, a fundamental heart frequency of the patient can be measured without the use of an ECG signal. In one method, the fundamental heart frequency can be determined by analyzing the size of the heart in the images. In another method, the fundamental heart frequency can be determined by applying a Fourier Transform. The measured fundamental heart frequency can thereafter be used to select slice images from the image scan for creation of a sagittal or coronal projection image. In exemplary embodiments, the resultant projection image can be used for coronary calcium detection and scoring.