Considerations

Risks and Considerations

Technical Risks

The primary technical risk is overburdening the PACS & VNA and causing an adverse impact on the operational performance of these systems.
To mitigate this risk, queries will be managed with a task queue. The system will enforce rate limiting of any commands sent to the PACS & VNA with an adapted token bucket algorithm which can be adjusted at runtime in response to system load. A circuit breaker will wrap the retrieval processes and act as fail-safe. Individual request retries will be subject to an exponential backoff strategy.

Security Considerations

Inbound access to the Cloud Environment in Azure

It is expected that a VPN connection (or ExpressRoute connection) between the on-prem UCLH estate and Azure will not initially be available.
Point-to-point firewall restrictions and Azure access tokens will manage secure communication between PIXL and the DICOM service.

Outbound access

All outbound connections will be over HTTPS. The existing proxy service will be relied upon to manage outbound access from the GAE.