Investigation of effect of pitch change on radiation dose in head and abdominal computed tomography scans: A phantom study

The aim of the study was to examine the pitch value, which is one of the parameters affecting the radiation dose. In both adult and pediatric head and abdominal Computed Tomography (CT) examination protocols, CTDIvol and DLP values were obtained at different pitch values using a phantom. The pitch values determined automatically by the CT device for adult head, child head, adult abdomen and child abdomen scans were recorded as 0.35, 0.6, 1.25 and 1.20, respectively. Then, scans were taken at pitch values of 0.6, 0.8, 1.0, 1.2, and 1.5 for adult head and abdomen. Statistical analyses were performed using OriginPro and SPSS statistical programs. According to the PCA (Principal Component Analysis) method, PC1 (Principal Component) was obtained as 58.93 %, PC2 (Principal Component) as 29.41 %, and the sum of both PCs was observed to constitute 88.34 % of the total variance. In the K-Means cluster analysis, two different classes were obtained. According to the CTDIvol and DLP measurements, it was observed that the measurement with the highest PC1 score was the adult abdominal CT scan with a pitch value of 1.5. According to the results obtained, it can be said that changing the pitch value affects the CTDIvol and DLP values, which are radiation dose indicators and found on the dose page. In addition, it can be said that it would be advantageous to use PCA and k-means cluster analysis, which are Unsupervised Machine Learning methods, on data obtained from computer-aided imaging devices such as CT.