X-Ray DOSIMETER Choice
As has been stated already in this thread, correct procedures and equipment are important when operating X-Ray equipment. With this in mind I did a review of my dosimeters to ensure that they were appropriate for use with the Faxitron and Mail scanner.
The sad truth is that most Geiger Muller based dosimeters are pretty much useless when used with X-Ray energies of less than 30KeV and even that level is too low for many meters. It should be understood that a meter with a detection capability of >50keV will not provide any meaningful reading when exposed to a 30keV X-Ray field. Always look for the keV capability rather than just the uSv specification !
My dosimeters are right on the edge of detection at 30keV, so I decided it was time for something better that matches my Faxitron's output.
Some research pointed me in the direction of the Thermo EPD MK2 range of dosimeters. The standard version is designed to detect and measure Gamma, Beta and X-Ray radiation at energies as low as 15 keV, which is perfect for use with the Faxitron. Various tests by official bodies have proven the EPD Mk2 unit to be very effective at low keV levels, unlike many other brands of unit. It uses three special pin diodes as the detectors rather than an ionisation chamber or Geiger Muller tube.
There are two down sides to the Thermo EPD however......
1. Price. They cost around $1000 each new.
2. Software configuration - the software costs $1000
Those prices are not hobbyist friendly but it is a health and safety device and such tend to be expensive.
I managed to find a new unit on ebay and negotiated a price of £200 which is still quite a sum but what value your health eh ?
Now to the software issue........ The Thermo EPD is quite a sophisticated device that can work stand-alone or as part of a monitored collection of units as in a team situation. The software contains a database and graphing software showing dose readings over time. Pretty useful but not cheap at $1000. The other issue is that the software can configure the dosimeter and disable some menu options to prevent tampering. That is all very well until you buy a used unit that has had its menus disabled ! As standard, the EPD can be configured using its built in menus, if these have been disabled to prevent tampering, the unit is basically locked to a specific configuration.
The EPD Mk2 communicates with a PC vis an IRDA interface so hopefully that part of the software control is not a problem. My unit should come in standard unlocked condition but just in case it doesn't, I have managed to obtain the EPD software.
Once the unit arrives I will advise on the Thermo EPD performance and whether I can access it via the software version that I have. Watch this space.
If anyone is thinking of buying a decent low keV capable Dosimeter, look out for the Thermo EPD Mk2 and NOT the Mk1 which is an old Siemens version that is a nightmare to control.
Aurora