Optimal tube potential and tube current for radiation dose reduction in routine adult head computed tomography scanning

ABSTRACT

We proposed a new, optimised scanning parameter that can reduce the patient’s radiation dose while maintaining image quality in a head computed tomography (CT) scan. We evaluated the clinical CT scan parameters (tube voltage, tube current, slice thickness pitch, scan range, rotation time, and CT dose index) for brain CT examination in a total of 52 multi-detector row spiral CTs (SOMATOM Definition AS+, Siemens Healthcare, Germany). The data were analysed, and the range of valid scan parameters was determined clinically using quartile distribution within the 95% confidence interval. The American Association of Physicists in Medicine performance evaluation phantom was used to acquire images using these scan parameters, and new, optimised CT scan parameters were proposed by analysing CT number accuracy, noise, uniformity, spatial resolution, and contrast resolution. The new CT scan parameters proposed were determined as tube voltage 100?kVp and tube current 300?mAs. Compared with conventional clinical scan parameters, tube voltage was reduced by 16.7% and tube current was decreased by 33.3%. Loss in imaging accuracy and uniformity of CT number was less than 20%, loss in noise was less than 40%, and no change in resolution was observed. Conversely, the CT dose index and effective dose was 20%–50%. A new systematic method for clinically assessing the optimised CT scan parameters were proposed, and the effective dose was decreased, with changing exposure conditions.