[ RadSafe ] Re: attn. Landauer Customers

[Sandy Perle]

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