Medical chart tracking based on long-range RFID
A paper chart passes from hand to hand — the front desk, doctors, offices, floors. Now you can see where every chart is, who took it and where they carried it.
- C#
- Java
- Android
- Chainway UHF RFID
- Firebird
- Excel/VBA
- IP cameras
A paper medical chart is needed by many people at once. The front desk and doctors work with it, it travels from office to office, from floor to floor, sometimes between buildings. Along the way a chart can end up out of place — and then it has to be found quickly. This is a technological challenge for every healthcare facility that keeps paper charts.
The clinic has 20,000–25,000 paper outpatient charts in active circulation.
A tracking system based on long-range radio-frequency identification (UHF RFID): it follows every chart as it moves around the building.
Tags
Every chart carries a UHF tag. I chose the Alien ALN-9662 (Higgs-3) with a large antenna, about 18 × 75 mm: it reads reliably in packed shelves and far from the reader. About 35,000 tags were purchased.
Readers
5 Chainway UR4 fixed readers and 12 antennas at entrances, exits, corridors and other key points of the building.
Server
A C# program polls the readers over the network around the clock, buffers the tags it reads and writes them to the database in batches. It recovers from lost reader connections on its own.
A photo at the moment of passage
When a chart passes under an antenna, an IP camera takes a picture: the time, the place, who took the chart and where they are heading. The photo is linked to the read by time, so no separate index database is needed — the right frame is found instantly. The photo archive keeps six months and holds its own size within set limits.
Records
The front-desk workstation: register a chart and retire it, send it to the archive, find it, run an audit, view the photo history of any chart's movements.
Archive search
An Android app for the Chainway R6 handheld RFID scanner, which connects to a phone over Bluetooth. A hot-and-cold search: in an archive with about 500 charts per square meter, the scanner narrows the search down to a stack of about 50. Charts that are out of place are found the same way.
The hard parts
Tags age
In their third year, some tags started losing their memory. The app gained a recovery mode for them.
Tags go around in a loop
At the yearly audit, tags are taken off inactive charts, reset and reused.
- C#reader polling server on the Chainway SDK.
- Java, Androidhandheld scanner app on the Chainway SDK.
- Firebirdchart movements.
- Excel/VBAfront-desk workstation.
- HardwareChainway UR4 readers, Chainway R6 handheld scanner, Alien Higgs-3 tags, IP cameras.
The long-range RFID tracking system covers 20,000–25,000 charts: for each one you can see where it is now, who took it and how it has moved. Nobody searches stacks and offices for a chart anymore — the system shows where it is.
Tags don't have to be bought every year — that's 6,000–7,000 a year. A stock of 10,000 will last roughly 10 years of growth.