## 2 Three-Dimensional Visualization Methods for Radiologists  
The rendering of two-dimensional images is discussed as a possible solution to this issue [1; 13]. Namely, cross-sectional images can be fused into a three-dimensional representation of data, for instance, in virtual reality (VR) [14; 15], augmented reality (AR) [15; 16], on stereoscopic displays [17; 18], or on volumetric displays [19; 20]. With the advent of modern imaging technologies, it was quickly apparent that traditional visualization methods do not facilitate visual search through vast datasets. The increasing demand for high-quality three-dimensional images in radiology was comprehensively outlined in the review by [PERSON] et al. [1]. This review pointed out that three-dimensional visualization systems, some of which were broadly implemented in the entertainment and gaming industries, had great potential to both display complex results from medical imaging examinations, such as computer tomography and magnetic resonance imaging results, and enhance the ergonomics of radiologists, in terms of the visualization and navigation through overwhelmingly large datasets. In this regard, the stereoscopic visualization of information has been one of the earliest proposed approaches. More than ten years ago, improved diagnostic accuracy was experimentally proven in digital mammography when stereoscopic displays were employed, compared to standard ones [17]. However, since then, the method has not been adapted in a clinical environment, and its benefits have been further studied in recent work [18]. Recently, the possible implementation of mobile stereoscopic systems (VR and AR) was discussed for education and training in diagnostic and interventional radiology [15], however, further confirmatory studies are required to prove the efficiency of the proposed methods. The first experimental assessment of VR's implementation in diagnostic radiology was conducted by [PERSON] et al. [14]. As no significant differences were demonstrated in lung nodule detection sensitivity, the findings indicated that the VR system might be as suitable as a traditional radiology monitor in the case of the detection of lung nodules. However, most radiologists reported the presence of physical and mental stress due to the VR system. The prolonged use of stereoscopic displays provokes discomfort, which occurs due to the mismatch between accommodation and vergence [21]. It is believed that the symptoms related to stereoscopic viewing can be eliminated in the foreseeable future by improving the resolution and sampling rate of the visualization system [14] or by utilizing a multifocal architecture for the optical element, which has originally been applied in volumetric displays within a wearable display [22]. With improvements in viewing conditions, stereoscopic visualization is expected to become acceptable for long-term use on a daily basis for the purpose of medical image reading. Compared with the stereoscopic visualization approach, the volumetric visualization of information is considerably less studied in terms of its possible application in the three-dimensional visualization of complex medical information. In contrast to stereoscopic viewing, for which the three-dimensional image rendering is required to be computed separately for each eye, the volumetric visualization system provides both eyes with the entire image. As a result, the accommodation and vergence are stimulated in a manner, which mimics natural viewing conditions [23], and no discomfort is experienced [21]. The capability of volumetric imaging systems to be implemented in medical diagnostics was highlighted recently [20], however, no results of professional users' performance have been reported. We believe that three-dimensional visualization systems can be used extensively in medicine. There is a wide range of potential applications, including teaching anatomy, facilitating visual search through multi-slice images, and communicating with patients [24].