Effect of x-ray tube voltage variation to value of contrast to noise ratio (CNR) on computed tomography (CT) Scan at RSUD Bali Mandara

Research has been conducted on the effect of variations in X-ray tube voltage to value of Contrast to Noise Ratio (CNR) on CT Scan at Bali Mandara Hospital using a phantom as a patient replacement. This research aims to determine the effect of X-ray tube voltage to the CNR value. Exposure factors used are X-ray tube voltage with variations of 80, 110, 120 and 135 kV, constant X-ray tube current of 150 mA and constant exposure time of 1 s. The readings of Io, Ib, and sb values in phantom images were performed using RadiAnt DICOM Viewer software (64 bit) and analysis of the effect X-ray tube voltage on CNR values was determined by regression test. The results of the analysis show that the variation of the X-ray tube voltage has a significant effect on the CNR value, where the greater X-ray tube voltage, the greater the CNR value. When the X-ray tube voltage is adjusted to 135 kV, the optimal CNR values are 113.52 for air, 35.06 for derlin, 13.93 for acrylic, 10.44 for nylon and 12.19 for polypropylene.