###### Abstract
A significant number of medical centers and physicians currently use freehand examinations for breast diagnosis, performed with more versatile conventional B-mode ultrasound (HHUS) scanners. Thus, there is a rationale and a market need to design a less expensive and more versatile system for the three-dimensional visualization of the structure of the entire breast system that is capable of working with any B-mode scanner and ultrasound probe. It may be expected that the availability of non-expensive primary or secondary screening techniques enabling 3D ultrasound imaging can widen the accessibility of screening tests supported by more comprehensive 3D breast structure reconstruction for women and increase their sensitivity accompanying MMG. Multi-angle conventional ultrasound imaging (MACUI) aims to fit into this area. The system has previously been proposed and evaluated by the authors of this paper [36]. Recently, a similar approach has been presented and tested by [PERSON] et al. [37]. Existing and developing models and prototypes of MACUI devices assume the use of linear ultrasound transducers mounted strictly horizontally under the breast tank in such a way that their rotation is performed accurately around the first piezoelectric element of the multi-element array B-mode probe. The novelty and essence of the MACUI system developed by the authors of this paper is to increase the volume scanning area of the breast, as well as to improve the quality and resolution of 3D ultrasound imaging of the breast structure by appropriately tilting the mid-length ultrasound B-mode probe relative to the horizontal plane and placed outside the rotation axis (Figure 1a). This can be motivated by the widening imaging area, which can cover entire transversal and sagittal sections, even for a large size. Additionally, the free space on the rotation axis surrounding leaves the space for the breast holder used for the stretching the female breast submerged in water and stabilizing the position during scanning [38]. The tilt of the probe allows for improved contrast and imaging resolution by using a method of superimposing and averaging images over a large area (compound imaging-CI) that are acquired at opposite angles (Figure 1a). In this way, it is possible to use somewhat lower ultrasound frequencies in order to increase the range without significant deterioration of the imaging quality. The spatial CI method is also used as an additional imaging modality in conventional HHUS, in the configuration shown in Figure 1b [39]. The essence of CI is to acquire multiple image frames at different angles, which are then digitally superimposed in accordance with the angle of scanning, e.g., by the proper averaging of pixels. The ultrasound beam is steered by a different set of predetermined angles (usually between three and seven), typically within 20 degrees of the perpendicular. The significant advantages of CI imaging include [40] the following: reduction in spots and noise (speckles), which improves tissue differentiation and increases the clarity of low contrast pathological changes; reduction in multiple reflections affecting the clear visualization of cyst content, better detection of microcalcifications, increasing the depth at which useful data are visualized; continuity of structures reflecting the ultrasonic wave affecting the highlighting of the outlines of cysts, canals, and connective tissue, better visualization of systems of linear striations in fat and muscles, improved presentation of the internal architecture of hard lesions; keeping the central acoustic shadow and acoustic amplification behind shading structures enabling the recognized diagnostic criteria for cysts and nodules; reduction in refractive shadows enabling rapid identification of suspicious shadows and improving the visibility of structures located, for example, behind the ligaments. With all of these advantages, CI imaging can be very useful for detecting and distinguishing between malignant and benign lesions in breast tissue in women.