[ RadSafe ] Re: attn. Landauer Customers

[Dale Boyce]

We concur, though our language may fool everyone else.

Dale
----- Original Message ----- 
From: "Sandy Perle" <sandyfl at earthlink.net>
To: <sandyfl at earthlink.net>; "Dale Boyce" <daleboyce at charter.net>
Cc: <radsafe at radlab.nl>
Sent: Wednesday, August 24, 2005 8:28 PM
Subject: Re: [ RadSafe ] Re: attn. Landauer Customers


> Hi Dale,
> 
> A few comments provided below:
> 
> On 24 Aug 2005 at 20:14, Dale Boyce wrote:
> 
>> Hi Sandy,
>> 
>> Of course I understand that geometry is part of it, but take a box
>> with very small dimensions, and a radioactive shipment with dose rates
>> high enough to expose the badges.  The radioactive shipment will
>> always have dimensions large compared to the  small box. Even if the
>> badge box was sitting on the shipment the dose rate across the small
>> box should not vary much.
> 
> This still depends on what the source is, what's between the source 
> and the box of dosimeters, the angle, the self-shielding within the 
> box of dosimeters, the orientation of each dosimeter in the box, etc. 
> Recall that the various elemental values are run through an 
> algorithm. If the pattern is "reasonable" then a dose is usually 
> assigned. It is not my accountability to second guess whether or not 
> a dose is "appropriate". What is my accountability is to inform a 
> client whether or not it "appears" that there was an inadvertent 
> irradiation of the shipment, and whether or not an assessment can be 
> made.
> 
>> However, the main point is how can one make a reasonable correction to
>> the report?  Assume a facility where the expected dose is next to
>> nothing, but that some people really do get exposures.  It is awfully
>> hard to justify either zeroing out the people that are likely to have
>> received the dose, or to believe the ones that shouldn't have had the
>> exposure.  Something that an automated process at the vendor would
>> have more trouble dealing with (possibly) than the vendor.
> 
> One should never zero out an exposure. As I stated above, the 
> responsibility for one's dose remains with the individual, and not 
> the processor. If we note the Controls have been irradiated, we don't 
> use them for subtracting elemental responses from the individual's 
> dosimeter elemental responses. We provide information on the report 
> that states that the controls were irradiated and what process we 
> used to provide for some subtraction. However, the individual needs 
> to accept, reject or provide a written estimate as to what they want 
> used for a dose for the respective period in question. I as a 
> processor will not make that determination.
> 
>> Probably the best solution if this occurs is to treat all the badges
>> as damaged/lost and to replace them with estimated doses, except in
>> the cases where the badges receive dose significantly higher than the
>> typical "in transit" exposure.
> 
> If all of the controls have an equal irradiation, and the spare 
> badges show the same elemental responses, on could consider using 
> those values as a subtraction for each element. Then the individual 
> assesses whether or not the result is valid. If there is variation 
> across the shipment, and nothing is statistically equivalent, then 
> the results should be rejected and an estimate be provide din lieu of 
> the dosimeter for that period. That is what we did in the power 
> reactor in that we had secondary electronic dosimetry worn. In that 
> most do not in the medical community or university environment, there 
> are other acceptable methods to derive an estimated dose.
> 
> Regards,
> 
> Sandy
> 
>> Dale
>> ----- Original Message ----- 
>> From: "Sandy Perle" <sandyfl at earthlink.net>
>> To: "Dale Boyce" <daleboyce at charter.net>
>> Cc: <radsafe at radlab.nl>
>> Sent: Wednesday, August 24, 2005 6:21 PM
>> Subject: Re: [ RadSafe ] Re: attn. Landauer Customers
>> 
>> 
>> > Hi Dale,
>> >
>> > This all has to do with source geometry, is it a point source,
>> > several point sources, or more like a line source. location of
>> > source(s), distance, angle, etc. This is not an unusual observation.
>> >
>> > Regards,
>> >
>> > Sandy
>> >
>> >
>> > On 24 Aug 2005 at 18:01, Dale Boyce wrote:
>> >
>> >> John's point is definitely a real one. While I have personally seen
>> >> doses as high as 300 mrem from intransit, I have seen a report come
>> >> back for a couple of thousand badges, several hundred of which had
>> >> exposures reported between 10 and 50 mrem with most in the 20 to 30
>> >> mrem category.
>> >>
>> >> Since these films were all shipped in the same box, one wonders why
>> >> the spread in reported exposure. Even though it is a lot of badges
>> >> when shipped as the film only the box is pretty small.
>> >>
>> >> Also, what correction could be applied in such a case if the
>> >> control showed 0, 10, 20, 30, 40, or 50 mrem?
>> >>
>> >> I guess one solution is to not use carriers that also handle
>> >> isotopes. The second best would be to not use the same carrier(s)
>> >> that deliver isotopes to your facility, since the most probable
>> >> place for the badges to be placed near a source in transit is
>> >> during final delivery. However, in the case mentioned different
>> >> carriers were used, but the one delivering the badges also does or
>> >> at least did transport RAM.
>> >>
>> >> Dale
>> >>
>> >>
>> >> ----- Original Message ----- 
>> >> From: "Wright, Will (DHS-PSB)" <WWright2 at dhs.ca.gov>
>> >> To: "Flood, John" <FloodJR at nv.doe.gov>; <sandyfl at earthlink.net>;
>> >> <jblute at NITON.com>; <radsafe at radlab.nl>; "Neill Stanford"
>> >> <stanford at stanforddosimetry.com> Sent: Wednesday, August 24, 2005
>> >> 5:03 PM Subject: RE: [ RadSafe ] Re: attn. Landauer Customers
>> >>
>> >>
>> >> i believe i deleted the initial strings, could someone briefly
>> >> describe the issue or was this simply a discussion about the
>> >> inconvenience of maintaining a control. controls are critical as
>> >> indicated in all objective science endeavors/ bench top science as
>> >> well as others will teach this the hard way.
>> >>
>> >> -----Original Message-----
>> >> From: radsafe-bounces at radlab.nl
>> >> [mailto:radsafe-bounces at radlab.nl]On Behalf Of Flood, John Sent:
>> >> Wednesday, August 24, 2005 2:52 PM To: 'sandyfl at earthlink.net';
>> >> jblute at NITON.com; radsafe at radlab.nl; Neill Stanford Subject: RE: [
>> >> RadSafe ] Re: attn. Landauer Customers
>> >>
>> >>
>> >> Perhaps I missed a post on this subject, but the discussion seems
>> >> to be overlooking the in-transit exposure that a control dosimeter
>> >> also monitors. There is no doubt that accurate background
>> >> subtraction is important to low dose measurements, but the absence
>> >> of background measurements can be a horrifying experience if every
>> >> dosimeter in the shipment to the processor shows a few hundred mrem
>> >> from irradiation in-transit.  This is a very real, modern problem -
>> >> if your dosimeters sit next to some clinic's radionuclide shipment
>> >> on the truck or in the warehouse, expect to see 50-300 mrem on
>> >> every dosimeter (how would I know this?).  Without control
>> >> dosimeters, life certainly gets more complicated.
>> >>
>> >> Bob Flood
>> >> Nevada Test Site
>