The TLD gives a measurement of dose absorbed in the
TLD (in mGy) with an accuracy of about
10%. However what we need to know is not the absorbed
dose in the badge, but the deep equivalent dose
(in mSv) in tissue. Remember that
is the equivalent dose at a depth
of 
or more in tissue.
There are many uncertainties involved in this assessment . Also, dosimeters worn on the surface of the body can at best be regarded as a statistical sampling device which provides a record of the dose received by one part of your body surface during your movements around the site.
When these factors are allowed for, we can expect an accuracy of about
50% in assessing
from a measurement of absorbed dose in a TLD.