# Applications of Digital Twin across Industries: A Review
## 4 Healthcare and Medicine  
Healthcare is one of the largest industries in the world and its integration in everyday living is ubiquitous. The DT technology in the healthcare system looks at the hospitals, operational strategies, capacities, staffing, and care models to optimize the care, cost, and performance of the healthcare industry, as well as help in informed and strategic decision making [79]. Besides facilities and infrastructure improvements, it also has applications in mimicking patients' behavior, and thus providing them a customized cure and care. Siemens has developed a DT for the radiology department for a hospital in Dublin, Ireland [80], which was facing challenges with delivering efficient patient care and experience due to rising patient demand, escalating clinical complexity, ageing infrastructure, a lack of space, as well as a longer waiting time, interruptions, and delays. Siemens, along with the hospital, redesigned the layout of the department and tested new operational scenarios by building a 3D computer model of the radiology department and its operations and then applying process optimization using 'Workflow Simulation'. To get a better insight into the department, they conducted a weeklong on-site assessment, which included workshops, interviews of stakeholders, and process observation. Within a few weeks of the implementation of the DT, a significant improvement was seen, resulting in shorter waiting times, a faster patient turnaround, better equipment utilization, and lower staffing costs [81]. In recent years there has been a shift within the industry from 'one size fits all' treatments/medicines towards the 'tailor-made' treatments, as the same disease can develop and affect different people differently based on their socioeconomic and geographic background, genetic make-up, pharmacogenomics, biological gender, age group, family medical history, and lifestyle choices; this is also referred to as personalized/precision medicine. DT technology fits right in the area of precision medicine as the DT outcomes depend entirely on the data fed to it (Figure 4). For personalized treatments, a DT can be conceived for the whole human body, or for just one body system (digestive system, respiratory system, etc. ), for a single body organ (liver, heart, etc. ), for finer body component levels (cellular, subcellular, or molecular levels), for a specific disease or disorder, or for other relevant organisms (e.g., a virus, interacting with one DT of a human body/organ) [82]. Despite this, unlike other industries, it is hard to establish a connection between humans and their DT because humans cannot be embedded with sensors. However, once the DT of humans is developed, it will be able to suggest the right treatment for the patient based on its data [83]. Even though human DT seem like a futuristic dream, digital models of organs and body parts have been developed. The Hewlett Packard Enterprise (HPE) launched the 'Blue Brain Project' to reconstruct and simulate a digital model of brains in order to understand the complexities and brain disorders at different levels [84]. Philips has developed 'HeartModel', which combines the data from the patient and a generic model of the heart to create a personalized 3D model of the heart for the early detection and prediction of cardiovascular diseases [85]. They have also developed a software suite called HeartNavigator, designed to assist with pre-surgery plans and tool selection by merging the Computerized tomography (CT) scan images with heart model and X-ray data. Another company, which is working on developing a DT of the human heart, is Siemens. They have been successful in simulating the physiological processes of a heart using magnetic resonance (MR) images and electrocardiograms (ECG) measurements which were used by cardiologists at the University of Heidelberg to predict the results of the treatment options to select the one with the most chances of success [86].