# Dose Mapping - How to relate back to Routine Monitoring Position

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#### CarlyH

Hi All,

I recently submitted a Dose Mapping study to an Auditor and have a query back from them:

"The calculation on page 8 of the Dose Mapping Study used addition and subtraction to calculate the maximum and minimum doses. This is a proportional calculation and should be presented as such.
> Please recalculate the routine dose based on proportional calculation."

The way we had calculated it was like this:

Difference between routine position (D1) and minimum dose (A3) = 31.9 kGy ? 30.7 kGy = 1.2 kGy
Therefore minimum dose accepted at routine position (D1) = 25 kGy + 1.2 kGy = 26.2 kGy
Difference between maximum recorded dose (C5) and routine position (D1) = 39.3 kGy ? 31.9 kGy
= 7.4 kGy
Therefore maximum dose accepted at routine position (D1) = 50 kGy (max allowed dose) ? 7.4
kGy = 42.6 kGy

Can anyone please comment on how we should be presenting this information?

thanks in advance, we are a bit stumped!

#### Stijloor

Staff member
Super Moderator
A Quick Bump!

Can someone help??

Thank you very much!

#### pkost

Trusted Information Resource
Please bear in mind I'm in no way an expert (or probably even a beginner) when it comes to gamma irradiation:

I believe that the dose difference will be directly proportional to the dose at the routine position dose. I think the auditor is asking you to consider this in your calculations...i.e. 1.2kGy will need to be reduced and the 7.4kGy will need to be increased.

Your maximum dose calulation at the moment risks an overdose of some areas.

C

#### CarlyH

hello pkost,
thanks for the reply. That was the intention of our original calculation, it turns out that there is a standard that exists for how to present proportional calculations but the auditor didn't tell us this.

We ended up re-calculating it based upon a ratio estimator as per a standard for dosimetry calculations as that was what we could find.

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