## 1 Introduction  
This study aimed to optimize the common iliac artery sonography images and avoid their misinterpretation, thus improving the diagnostic accuracy. The current ultrasound technique is subjective and strongly dependent on operator qualification during the examination's acquisition and interpretation phases. Thus, maintaining high-quality characteristics and reproducibility in routine protocols is challenging in the clinical field. Some limited data for the optimization of sonography images can be provided by available commercial liquid (water, gelatin, etc.) phantoms containing several compartments simulating human body parts [1; 2; 3; 4]. In particular, liquid phantoms with a quantified scale are instrumental in routine quality assurance in clinical surveys. Thus, [PERSON] et al. proposed a customized heart phantom to effectively evaluate myocardial perfusion [5]. [PERSON] et al. applied a simple liquid phantom to optimize the artifact or uniformity in material and claimed its wide flexibility and low cost [6]. [PERSON] et al. developed a homemade gelatin phantom to simulate the abscess of soft tissues [7]. The water phantom previously proposed by several coauthors of this study provided a clinically confirmed optimization of the left anterior oblique caudal imaging in coronary angiography using [PERSON]'s method [8]. This study extends the above approach by designing a unique water phantom, which is precisely assembled to simulate real common iliac artery stenosis in clinical examination. Furthermore, every specific factor of the water phantom can be adjusted or replaced to fulfill the researcher's demands. Its application combined with the Taguchi analysis allows one to optimize the performance of sonography imaging.  
Most relevant works provide such optimization by a single factor related to one specific quality characteristic. For instance, [PERSON] et al. listed all the possible factors dominating sonographic imaging quality and compared them one by one in optimizing the quality [9], [PERSON] et al. and [PERSON] et al. tried to adopt a deep learning-based system to optimize the imaging quality from postprocessing of acquired images [10; 11], and [PERSON] et al. claimed that the clutter filtering technique can improve the sensitivity and specificity of power Doppler imaging [12]. In contrast, [PERSON]'s method, as proposed in this study, provides a robust multifactor analysis on the basis of a conventional setting in routine examination.  
The five main factors influencing the sonography image quality are the angle of the probe, water depth, sonography preset frame rate, amplitude gain, and imaging compression ratio. These factors are optimized in this study via the above approach. The assembled water phantom contained two major compartments and properly functioned in controlling the physical characteristics to simulate the bloodstream along the common iliac artery and environmental setting. The analog model representing a clinical syndrome of artifacts in sonography imaging was realized as artificial stenosis with a diameter of 8 mm inside a silicon pipe with a diameter of 19 mm.  
[PERSON]'s methodology and the related calculations were described in the materials and methods, whereas the unique signal-to-noise ratio as a quantified index of quality characteristics was also involved. The dataset from the original sonography multiple scans was processed and discussed in detail. Accordingly, [PERSON]'s analysis was successfully applied to improve the performance of common iliac artery sonography imaging. The benefit of adopting the acquired area rather than the diameter in the clinical cardiac examination was also analyzed and confirmed.