## 2 Materials and Methods
### Qualitative Image Analysis  
On the denoised sparse-sampling CT of 50 test cases, the normal and abnormal lesions were visually evaluated. For the qualitative evaluation, four radiologists were participated, two performing visual assessments as readers and the other two defining and extracting lesions to be assessed. The two groups were independent of each other. As readers, two board-certified radiologists (with 17 and 10 years of experience, respectively) independently evaluated the denoised CT images and referred to the original images on 3D Slicer (version 4.10.2, [[https://www.slicer.org/](https://www.slicer.org/)]([https://www.slicer.org/](https://www.slicer.org/))) [24]. For all visual evaluations described in the following section, we used a five-point scale as follows: (1) Unacceptable, (2) Poor, (3) Moderate, (4) Good, and (5) Excellent. The definition of each score and detail procedure of qualitative evaluation is shown in Tables 1-3 and Appendix B, respectively. The image quality evaluation of the entire CT and the normal local lesions were evaluated. For the entire CT image quality, (A) Overall image quality and (B) Noise and artifacts were evaluated. The overall image quality represented a comprehensive evaluation, including noise, artifacts, and visibility of anatomical structures. As an evaluation of the normal local lesions, the visibility of the iliac artery (the common iliac artery, internal iliac artery, and external iliac artery) was evaluated. A score was given on whether or not the diameter could be reliably measured at each of the three points of the common iliac artery, internal iliac artery, and external iliac artery. Peritoneal dissemination, liver metastasis, and lymph node metastasis were visually evaluated as abnormal lesions by the two radiologists. The abnormal lesions were determined by the consensus of two other independent board-certified radiologists (6 and 14 years of experience, respectively) on the original CT image based on the following criteria. Peritoneal dissemination was defined as previously established as either 1) an isolated mass or 2) subtle soft tissue infiltration and reticulonodular lesions [25]. Lymph node metastasis was defined as short axis \(\geq\)10 mm. With reference to RESIST v1.1, we defined peritoneal dissemination and liver metastasis as follows: peritoneal dissemination for non-measurable or measurable (long axis \(\geq\) 10 mm); liver metastasis (long axis \(\geq\) 10 mm) [26]. The measurable lesions of peritoneal dissemination were further subdivided into long axis \(\leq\) 20 and \(>\) 20 mm because the staging of FIGO 2014 differs depending on the size [27]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Score** & & \\ \hline
1 & Unacceptable & non-diagnostic \\
2 & Poor & poor visualization, heavily blurred appearance of structures \\
3 & Moderate & moderate visualization, moderate blurring \\
4 & Good & good delineation, slight blurring \\
5 & Excellent & excellent visualization, sharp delineation (equivalent to or better compared \\  & & with the original image) \\ \hline \hline
**Score** & & \\ \hline
1 & Unacceptable & heavily noise and artifacts, structures are not visible on entire CT image \\
2 & Poor & heavily noise and artifacts, structures are not visible on most parts of CT image \\
3 & Moderate & moderate noise and artifacts, but acceptable for clinical evaluation \\
4 & Good & minor, but slight noticeable noise and artifacts are found compared with the original image \\
5 & Excellent & noise and artifacts levels are equivalent to or better compared with the original image \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Score criteria for entire CT image quality.