On Mon, 05 May 2008 12:10:38 -0400, you wrote:
>Quoting Steve Moulding <
fti1983@...>:
>
>> Anyone on the list have experience / knowledge of using PIC microcontrollers
>> which may be exposed to X-ray beams? A customer has an application for use
>> in radiation therapy rooms, and the electronics package will occasionally be
>> in the path of the therapy beam during patient exposure; due to the nature
>> of the package, this is unavoidable. The question is: will this eventually
>> cause the electronics - specifically the microcontrollers - to fail? Some
>> empirical testing done Saturday in a Cancer Center showed that the
>> microcontrollers will eventually fail, but only after extended exposure -
>> approx. 1 1/2 hours in a continuous beam, something that will not happen
>> with a patient. If the package is exposed intermittently, will the
>> radiation effects be cumulative? Tried Microchip & Google with very little
>> useful info uncovered. Thanks,
>> Steve
If things only ahppen after extended exposure, it is reasonable to assume there is a cumulative
effect.
You should certainly implement checks on program memory & eeprom integrity, but the primary defence
should be lead shielding to avoid the exposure in the first place. I'd think that even a relatively
small thickness would provide a substantial improvement over nothing.
You may also want to look at reducing expiosure by suitable orientation - if you can arrange the
electronics to be side-on instead of face-on to the beam, this will reduce the effective dose
substantially.
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