# Advancing Phantom Fabrication: Exploring 3D-Printed Solutions for Abdominal Imaging Research
## 3 Results  
This study investigated the impact of various scanning and reconstruction parameters on the image quality of phantom abdominal scans. Table 2 summarizes the utilized settings, including the tube voltage (kV), tube current (mA), rotation time, pitch, slice thickness, computed tomography air kerma index (CTDI\({}_{\text{vol}}\)), and convolution kernel. Automatic tube current modulation (ATCM) was employed during scanning. The CT scanner's ATCM system utilizes standard deviation (SD) as an image quality metric, with a pre-defined threshold of 12.5 in this study. This resulted in a dynamic anode current range of 50 mA to 300 mA, adapting to each layer within the ROI (as shown in Table 2). To assess reproducibility, specific series were scanned multiple times. The FC18 convolution kernel, known for its noise reduction and smooth image generation, was used as the standard  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \begin{tabular}{c} **U** \\ **(kV)** \\ \end{tabular}  & \begin{tabular}{c} **I** \\ **(mA)** \\ \end{tabular}  & \begin{tabular}{c} **t** \\ **(ms)** \\ \end{tabular}  & \begin{tabular}{c} **p** \\ **(mm)** \\ \end{tabular}  & \begin{tabular}{c} **T** \\ **(mGy)** \\ \end{tabular}  & \ \begin{tabular}{c} **CTDI** \\ **(mGy)** \\ \end{tabular}  & \begin{tabular}{c} **Kernel** \\ **Kernel** \\ \end{tabular}  \\ \hline Series & 1 & 80 & 300 & 750 & 0.816 & 0.5 & 3.9 & FC18 \\  & 2 & 100 & 153 & 750 & 0.816 & 0.5 & 4.9 & FC18 \\  & 3 & 120 & 87 & 750 & 0.816 & 0.5 & 6.0 & FC18 \\  & 4 & 135 & 80 & 750 & 0.816 & 0.5 & 7.6 & FC18 \\  & 5 & 80 & 300 & 750 & 0 kernel. Conversely, the FC08 kernel was employed for scenarios requiring enhanced sharpness and higher resolution. The evaluation results of the visualization of the appendix simulation obtained by non-linear fitting, described through parameters \(C\), \(D\), and \(\sigma\), are presented in Table 3. Figure 4 shows how the contrast, that is, parameter \(C\), changes depending on the anode voltage. Contrast (\(C\)), defined as the difference between the mean values of the CT numbers in the selected object (the simulation of the appendix) and the background (the simulation of the soft tissue in the abdomen), is an indicator in assessing the ability of the system to distinguish objects from the background. It can be observed that there is a significant positive correlation between the two variables. The mean value of parameter \(C\) at 80 kV is 818 HU, while at other values of the anode voltage, it is significantly higher. Thus, at 120 kV, which is a value often used in common scanning protocols, \(C\) has a mean value of 881 HU. This dependence on the anode voltage is expected, considering that the general definition of Hounsfield units depends on the radiation energy and thus on the anode voltage. Also, the possible dependence of the parameter \(C\) on the convolution kernel was examined, but no significant difference between the FC18 and FC08 kernels was observed (Mann-Whitney \(U\) test, \(p=0.594\)). The sharpness of the appendix display, that is, the value of the parameter \(\sigma\), did not depend on the tube voltage. A significant correlation cannot be observed in Figure 5. Also, there is no significant difference between the value of \(\sigma\) obtained using different convolutional kernels in image reconstruction (Mann-Whitney \(U\) test, \(p=1.000\)). The third parameter of interest, which is related to the visualization of the appendix, is the diameter of the visible object (\(D\)). No significant difference was expected between the different series of scans, which was confirmed by the correlation test between \(U\) and \(D\) (\(p=0.357\)) as well as by the comparison between different convolutional kernels (Mann-Whitney \(U\) test, \(p=1.000\)), which is also observed in Figure 6.  
The 3D-printed phantom exhibited excellent morphological similarity to both a human abdomen and a commercially available phantom, as confirmed by the HU values of CT imaging.