# MIDOM--A DICOM-Based Medical Image Communication System
## 1 Introduction  
The volume of medical data (mostly multi-dimensional, such as images, videos, and volumes) in modern hospital information systems (HIS) can easily exceed dozens of terabytes. Utilizing efficient compression techniques in these environments brings benefits from both a financial and functional perspective. In addition to reducing storage costs, exchanging medical data in distributed environments of connected and mobile devices is also required to increase efficiency and reduce communication costs (bandwidth, latency), battery consumption, user experience, etc. Lossless compression techniques are used in medical applications even though they result in a modest compression ratio compared to lossy compression. However, the reversibility of lossless compression is vital in remote diagnostic consultancy and diagnostic data archival since it does not introduce artifacts into stored data and provides perfect reconstruction of medical images when acquired from the underlying PACS (Picture Archiving and Communication System). The European Union's General Data Protection Regulation (GDPR) came into effect on 25 May 2018, as a piece of data protection legislation within the EU and had much impact onthe global technology development [1]. It is important to stress that GDPR considers health data as a particular category for data protection, together with its US counterpart, named the Health Insurance Portability and Accountability Act (HIPAA). These data protection laws even inspired some researchers to work on de-identification techniques to additionally protect the identity of subjects [2]. As GDPR applies only to EU health data and HIPAA covers the USA, patients' health data are not protected worldwide. Results of a study by [PERSON] et al. [3] analyze the use of instant messaging apps showing these are still in use. One example is Botswana, where doctors use instant messaging apps such as WhatsApp for telepathology [4] even though WhatsApp does not comply with GDPR, which is further confirmed by the EU's second-largest GDPR fine of EUR 225m directly to WhatsApp [5]. As DICOM (**D**igital **I**maging and **C**ommunications in **M**edicine) contains health data, its access is usually limited only inside the institution's network. There are several ways to make these data remotely available, such as the use of virtual private networks (VPN), sharing the images using CDs or online services, or using cloud PACS. There are several issues with these; a VPN requires configuration or even software installation on computers that users use to connect to the PACS; sharing the images using the CD or public online services usually does not provide enough privacy protection. Cloud PACS stores the private health data on other companies' servers which may be contrary to the laws such as GDPR or HIPAA. Privacy is not the only issue when accessing the DICOM files remotely. Downloading a 1 GB file which a modern CT scanner produces using a typical download speed for 2G (EDGE) of 0.1 Mbit/s will take more than 22 h; using a 3G (HSPA+) at 4 Mbit/s will take 44 min; using a 4G (LTE cat 4) at 15 Mbit/s will take 3 min; while on 5G at 150 Mbit/s will take less than one minute. With no size reduction in such files and using a slow network speed, such as a 2G or 3G network, it will take too long to download them for fast analysis. Such network types are still the most common in some relatively underdeveloped parts of the world, where doctors use instant messaging apps for data sharing [6]. As instant messaging apps automatically use lossy image compression to decrease upload and download time, shared images are losing information, which may result in an incorrect diagnosis. This paper demonstrates MIDOM, **M**edical **I**maging and **D**iagnostics **o**n the **M**ove, a complex system used for the efficient and secure exchange of medical images over a broad spectrum of connection profiles and devices.