microSTAR®ii User Manual v1.3 66
If you are experiencing an issue with the sensitivity of your nanoDots, contact LANDAUER for
assistance (See section 12.1 for contact information).
The Sensitivity Assessment tab features are used to assess the sensitivity for each nanoDot in a test
population that has been exposed to a precisely known dose. The re-computed sensitivity is referred
to as the Measured Sensitivity (S
m
) or Adjusted Sensitivity (S
corr
) and is given by S
m
= S
adj
= S
lab
* SAF,
where SAF is the Sensitivity Adjustment Factor (SAF).
The SAF is the conversion factor, which when multiplied with the labeled sensitivity value results in
a corrected sensitivity. From the assessment, a new SAF can be saved.
By default the microSTARii system operates with a SAF value of 1.0 for each dosimeter using a Linear
dose calculation formula that shows a default SAF value of 1.0. The SAF for each dosimeter in a
population can be evaluated computationally, and a report can be generated without modifying the
existing SAF value stored in the database.
9.4.1 Test Conditions
For a valid sensitivity assessment, the test must be run in the following conditions:
• Prior to running the assessment, the reader performance stability must be established. The
reader must be recently calibrated using calibrates that have been exposed under the same
conditions as those in the test population of nanoDots.
• The exposure or dose level should be known to a very high degree of accuracy, ideally within
1%. The population of test nanoDots can include one or more dosimeters, but for best results
at least ten dosimeters.
• If dosimeters are exposed in separate groups, it is recommended that an ionization detector is
used to confirm consistent exposure levels between groupings.
• Each dosimeter should be read at least four times on the reading screen under the same
conditions (using the same calibration selection, beam mode, etc.).
• A new Process ID for the population should be entered for all dosimeter readings obtained in
order to identify the population.
• The exposure should exceed 100 rad to ensure good counting statistics.
9.4.2 Sensitivity Assessment Test Calculations
The Sensitivity Assessment Test averages a set of dose measurements and compares that information
to the known dose level to determine how closely they match. The accuracy rate increases as the
number of dosimeters in the set increases. If 4-5 readings of each dosimeter in the set were averaged
to obtain the dose of the nanoDot, and the readings were very reproducible (low CV), the reading and
known dose should closely match.
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