## 6 Challenges and Perspectives  
Even though numerous studies in the MSU have shown promising results in terms of bringing prehospital diagnosis and treatment to stroke patients within the golden hour, a number of challenges remain that need to be addressed in order to facilitate the development of the MSU, in particular within the Air-MSU, where the need is greatest for regional and remote locations in Australia.  
The major challenge persists in finding an optimal balance between minimizing the weight while maximizing the structural integrity of the support structure. The support structure must be designed to withstand the static weight of the CT scanner, the rotational force induced by the rotating drum when it is spinning during scanning, and the vibrations induced by the helicopter floor during flight. One such property that is important to ensure is that there are no severe stress concentrations located on the profile of the support structure and that it demonstrates sufficient structural strength. Hence, topology optimization, which is a mathematical method that optimizes material distribution within a given design space, would allow us to optimize the support structure by maximizing its stiffness-to-weight ratio and removing underutilized material where possible to reduce the weight of the structure.  
In addressing the impact of vibration, an initial component of a successful impact assessment procedure is to start by reviewing the 3D design early in the design process, then conducting the virtual realization, which consists of computer modelling and simulation to identify the sources of vibration, which may be of concern for the integration of the proposed CT scanner into an aircraft. The level of vibration in terms of the fundamental resonant frequency, damping, amplitude, and mode shape will be determined with the spaces and layouts of a given aircraft design. The simulated data will then be shared and reviewed with the equipment suppliers or manufacturers to check the specification criteria and vibration responses for their specific lines of CT scanners. This will assist the design team to devise some typical base strategies that can be implemented or considered in working to mitigate the vibration impact on the proposed CT scanner. A mitigation solution may involve reinforcing the aircraft floor and incorporating vibration suppression and stabilization for the CT scanner system.  
Medical device manufacturers face countless challenges that require them to be flexible to make a decision on 'go' or 'no-go' and modify the project plan to meet the required quality, safety, and performance standards while ensuring the traceability of information and intellectual property throughout the development process. To address such challenges, we need to look beyond the constraints of the existing norms and practices, as well as the biomedical domain of expertise. Thus, the proposed 'V' model of the system engineering approach, which allows for virtual analysis, testing, and validation, and in parallel connecting to the physical assets, is considered as the most promising choice.  
Any modification to the existing CT scanner may lead to manufacturers and users to question the overall safety while maintaining good-quality images of the newly modified lightweight CT scanner. This question could be addressed systematically by following standardized protocols to equip the modified lightweight CT scanner with safeguards and shielding. This certainly requires the collaboration and development in partnership with the medical device manufacturers, where validation and verification will be carried out in collaboration with aircraft solutions companies and CT scanner manufacturers in accordance with the specifications and quality attributes listed in TGA and CASA guidelines.