I’ve bought an affordable geiger counter board that fits on a Raspberry pi zero (https://www.tindie.com/products/granzscientific/raspberry-pi-zero-iot-geiger-counter/).  I’ve modified original software and added some scripts to send radiation readings to the APRS network. I’ve also added a Munin plugin. Go to the github project site for instructions: https://github.com/s55ma/granzscientific-geiger-counter-APRS