Automated Slice Thickness Measurement on the Nessoft CT QA Phantom

Purpose: This study proposes a method for automatically measuring slice thickness on image of the Neusoft CT quality assurance (QA) phantom. Method: The Neusoft CT QA phantom was scanned by a Neuviz 16-slice Neusoft CT Scanner. Automated measurement was implemented using IndoQCT software, while manual measurement was conducted using MicroDicom viewer as comparison. The system was evaluated on images with variations of slice thickness (i.e 1.25, 2.5, 3, 5, and 10 mm), tube voltage (i.e. 80,100,120, and 140 kV), and tube current (i.e. 77, 154, 231, and 233 mA). Results: The results of automated slice thickness method for slice thicknesses of 1.25, 2.5, 3, 5, and 10 mm were 1.47 + 0.17, 2.67 + 0.08, 3.21 + 0.17, 5.21 + 0.13, and 10.95 + 0.28 mm, respectively. By comparison, the results of manual slice thickness method were 2.91 + 0.17, 3.28 + 0.29, 3.56 + 0.29, 4.72 + 0.27, and 11.35 + 2.03, respectively (p-value 0.009, 0.002, 0.047, 0.008, and 0.714). The results of automated method for tube voltages of 80,100,120, and 140 kV were 5.61 + 0.34, 5.12 + 0.23, 5.08 + 0.23, and 4.98 + 0.28 mm. By comparison, the manual slice thickness method results were 4.71 + 0.39, 4.82 + 0.54, 4.89 + 0.50, and 4.79 + 0.43 mm (p-value 0.005, 0.291, 0.473, 0.452). The results of automated method for tube currents of 77, 154, 231, and 233 mA were 5.19 + 0.26, 4.98 + 0.28, 5.06 + 0.41, and 4.96 + 0.13 mm. By comparison, the results of manual slice thickness method were 4.42 + 0.34, 4.92 + 0.11, 4.72 + 0.37, and 4.80 + 0.46 mm (p-value 0.004, 0.642, 0.22, 0.75). Conclusions: An automated slice thickness measurement on Neusoft CT the QA phantom image was successfully developed. The measurement results of the automated method are closer to the set thickness than the manual method. The results of automatic slice thickness method are accurate for tube voltage, and tube current variations.