932512A / 0114
ORTEC
®
EASY-NIM
™
928 Suite
27
Factor
Correction
*
Time
Live
Counts
*
c
b
a
MDA
Figure 32. MDA Preset Tab.
The MDA presets are implemented in the MCB; that is, the entries you make on this screen are saved in the MCB
memory and have no direct link to MDA methods selected in the analysis options for applications such as
GammaVision, ScintiVision
™
, ISOTOPIC, etc. The MDA preset calculation uses the following formula:
where:
a
,
b
, and
c
are determined by the MDA criteria you choose.
Counts
is the gross counts in an ROI that is 2.5×FWHM around the target peak energy.
Live Time
is evaluated in 40 second intervals for the MDA presets.
Correction Factor
is the product of the calibration efficiency at the specified peak energy and the peak’s branching
ratio (yield) as listed in the working (active) library.
●
To add an MDA preset, enter the preset value in the
MDA
or
Correction
field; select the
Nuclide
and
Energy
;
enter the desired values for coefficients
a
,
b
, and
c
; then click
Add New
.
●
To edit an existing preset, click to highlight it in the table. This will load its
Nuclide
,
Energy
, and coefficients in
the lower sections of the dialog. Change as needed, then click
Update
.
●
To remove a preset, click to highlight it in the table, then click
Delete
.
NOTE
MAESTRO does not support efficiency calibration. The efficiency component in the
Correction Factor
is
set to 1.0; the preset field is labeled
Correction
instead of
MDA
; and the preset is based on counting
activity (cA) instead of becquerels). You can enter the MDA preset either in counts; or corrected for
factors such as sample volume, attenuation, or calculated efficiency. For example, if you manually
calculate the efficiency for a peak, you can enter a corrected MDA target value by multiplying the desired
MDA value times the calculated efficiency, and entering the product as the
Correction
.
