## 2 Literature Review
### Collaborative Medical Decision-Making and Blockchain
The study proposed 'MedRec', a platform that works on PoW to manage EHR transparently. The study [64] rewarded miners unwanted access to EHR. Therefore, the study seriously hampered personal information privacy. In comparison to that, the proposed PoF protects the complete identity of the participants by restricting the access of third parties. [PERSON] [33] proposed a'modelchain' that used machine learning and blockchain technology to simplify patient-centered outcomes research (PCOR). In one side, the study hid node identity and on the other side proposed inter-institution collaboration with a consortium blockchain. This architecture decreased the trust of the overall system many times. On the contrary, this study (PoF) exposes user identity to the consortium chain. This ensures easy identification of the corrupted node. [PERSON] [34] proposed gene token as a medium of gene information exchange. An off-the-chain and on-the-chain gene data storing platform were proposed by the study [34] that provided a scheme for sharing biological data among third parties. [PERSON] [59] proposed privacy aware health data management with blockchain technology. The study proposed four separate layers under clinical trial. They were: (a) A distributed paradigm with blockchain technology; (b) application information management; (c) secure and anonymous identity management; (d) privacy-preserved trusted information management. However, the study failed to adopt standard blockchain architecture. That is, the lack of coherence among presented components reduced the large-scale implementation scope. On the other hand, PoF based complies with both standard blockchain architecture and existing privacy standards. [PERSON] [28] proposed a 'fast healthcare interoperability resources (FHIR) chain' for collaborative clinical decision-making. The study identified four key challenges of collaborative medical decision-making in healthcare. Security concern, lack of trust, scalability concern, and lack of exchanged data standard are the barriers of collaborative clinical decision-making. The PoF based study successfully responded to all the aforementioned issues to propose an efficient collaboration scheme. [PERSON] [65] proposed EMRs sharing blockchain platform in collaboration with Stony Brook University Hospital. The study used oncology-specific data aggregation from patients and doctors. This study also uses off-chain data storage. However, no concrete consensus gathering was proposed. [PERSON] [66] and [PERSON] [60] analyzed the performance of blockchain-based PHI exchange platforms that preserve privacy. Another study [67] proposed a hierarchy based blockchain wallet called 'Youbase'. As 'Youbase' stores personal information in a tree-like structure with keys (public and private), it can store information separately regardless of data type. Personal data are anonymized to comply with the GDPR. However, consensus gathering time is an issue of this study. Another study [68] had also mentioned that the transaction rate and waiting time may doubt the large-scale use of blockchain. On the contrary, the proposed study successfully addresses those issues by reducing the block size and increasing the transaction rate. Another study [55] explained the need for a new blockchain architecture to overcome existing privacy issues. As aforementioned studies have already questioned the integrity of stakeholders, blockchain, with no central authority, is a possible solution to bring trust to medical collaboration. This study, therefore, finds a valid cause to use blockchain in medical decision-making in support with existing studies previously discussed. Table 3 compares the proposed study with a few other studies [28; 61; 65; 69; 70]. During comparison in Table 3 key contributions of the proposed PoF based medical decision-making system are considered.