Do a search for "MightyOhm Geiger Counter Kit Bundle" and you will find a stand alone version of the same circuit along with photos. Although the PCB has a "High Voltage" label, it is powered by 2 X AAA batteries which are might be very lethal if ingested.\s
Powered by 2x AAA batteries != not high voltage. Boost converters can reach high voltages pretty easily. That's why you can get USB powered nixie clocks, for example.
You can shock the hell out of yourself with the capacitors for the flash in a disposable camera, so the AAA battery source isn't exactly exculpatory...
