Complex Matter

Problem Statement

Our client asked us to design and implement an application that complies with radiation protection requirements and supports quality management for nuclear medicine and radiochemical equipment.
Within the framework of the “Landesprogramm Wirtschaft”, the project was also funded by the European Union.

Inspection of Medical Devices

In nuclear medicine facilities, instruments are used to measure radioactive radiation. To ensure they provide correct values, they are regularly checked with so-called test sources. The measurement results must fall within defined tolerance ranges to confirm usability.

Documentation and Regulations

The inspections must be documented, evaluated, archived, and made accessible to the responsible authorities in accordance with the Radiation Protection in Medicine Guideline and DIN 6855-11.
Previously, this was done with Office documents, paper, email, and fax – a manual process prone to errors.

Additional Requirements

In addition to the inspection of measuring devices, work instructions, regulations, and approvals must be available, and operational incidents documented. Smartarchivo integrates all these requirements into one central system.

Goal Definition

Based on the requirements, an application was created that digitizes the entire documentation and inspection process:

• a server-side web application for administration, reports, and documentation

• a native tablet app for recording measurements and accessing instructions and operating logs

Challenging Conditions

The solution had to meet strict authentication procedures for reporting while also being offline-capable, since many measurements take place without internet access.
A major challenge lay in the modeling: over 20 different data structures had to be mapped in a generic, polymorphic schema.

Technical challenge

The biggest technical hurdle was to understand the physical relationships of the different device types and measurement methods and to transfer them into a homogeneous modeling and implementation. In the process, more than 20 similar but not identical data structures were identified. In order to express the series types and limit value calculations, which are based on radioactive decay on the one hand and on continuity on the other, in a generally valid model, a generic schema was designed whose expressions were enabled to map the required polymorphisms with the aid of single-table inheritance.

Product Design

The product was designed to provide users with a clear, intuitive interface despite complex processes.

• Reduction of the UI to context-relevant options

• User flows as a basis for consistent processes

• Granular, configurable role and permission management

In order to be able to reduce the interfaces for operating the application as much as possible, we have planned an extremely fine-grained role and rights management. With the help of this, the range of functions - and thus also the options of the interfaces - can be minimally configured for each individual user according to requirements.

In order to define the individual views required on the basis of the planned product features, wireframes were created for the majority of the complex use cases, anticipating future implementation. Based on the wireframes, we created a foundation at an early stage of the product development that allowed us and our client to ensure functional correctness, technical feasibility and optimal usability.

User Interface Design

The interfaces of the tablet app and web application were implemented as modular libraries following the principles of Atomic Design. As a result, they are consistent, extendable, and efficient in further development.

To accommodate the different device-immanent operating concepts of the tablet and web application, the two component libraries differ significantly. Operation with the help of a pointing device - such as a mouse - has different requirements than operation by touch input. Thus, there is a great deal of agreement in the general product-specific style, but significant differences in the individual UI elements relevant to operation, such as buttons, input or navigation elements.

Tablet application

The Android app enables convenient recording of measurements, documentation of incidents, and access to instructions.
An integrated calculation logic checks values in real-time against tolerance limits and immediately provides plausibility feedback.

Server-side application

The web application is based on the Propeller Framework and uses RESTful JSON APIs with JWT authentication. Persistence is provided by PostgreSQL.

The UI kit delivers consistent components for future extensions. Reports can be created on a tenant-specific basis and securely forwarded to authorities via UUID-based URLs.

At the API level, RESTful JSON is used as the protocol. We chose JSON web tokens as the authentication method. Statelessness at the protocol level makes it easy to solve some of the issues that arise from offline requests.

API endpoints are routed directly to controller implementations, which perform authorization checks and data plausibility at instantiation. This ensures that unauthorized or invalid accesses are rejected even before controller methods are executed.

A PostgreSQL database is used as persistence system.

The API documentation is provided directly by the framework, including sample requests, which greatly simplifies the development of API clients.

Reporting

The reporting of the measurement series documentation can be configured using the web application in such a way that the relevant measurement series for selected devices and a specific time period are summarized in a report. The report is supplemented by an extract from the logbook for the selected period.

For each report, a non-guessable URL is generated based on UUIDs and assigned an access key. This information can then be passed on to the relevant supervisory authority. The content and preparation of the report data has been fine-tuned to ensure that it is accepted by the authorities.

Testing and distribution

In order to be able to continuously maintain and develop the product without jeopardizing the stability and performance of the existing functionality, test scenarios were designed for all API endpoints and the required tests were defined. In this way, both function and performance can be tested automatically as part of black-box tests. This involves running the test scenarios for an appropriately prepared client and validating the results at the protocol and response level, as well as checking them against performance budgets.

The tests are performed when each new version is transferred to the version control system. Only after passing all test scenarios can the respective version be released to the staging or production environment. Thus, different versions are available at different stages.

All commissioning actions, such as build, testing and stage-based distribution, are configured, versioned and executed within the CI/CD functionality of the version control system.

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