The objective of this study was to quantify the radiation dose reduction without impairing image quality, using 100 and 120 kiloVolts acquisition protocols. We analyzed 37 non-obese patients in a private hospital in Santiago, Chile, of which 20 were obtained with a protocol of 120 kiloVolts and the remaining 17 with low energy protocol. The quality of the image was evaluated quantitatively and qualitatively. The average image quality score for the 120 and 100 kiloVolts groups was 3.25 ± 0.8 and 3.41 ± 0.7 respectively, demonstrating an improvement in the image quality, although at a non-significant value (p= 0.58). In the images obtained with the 100 kiloVolts protocol, a reduction of 41.99% in the radiation dose was demonstrated in addition to a significant increase of the intensity of the signal and the noise. It was possible to demonstrate a decrease of the radiation dose without detriment in the diagnostic image quality in coronary angiography using computed tomography.