The following screen shot shows the raw data (on and off-peak) for a monazite grain (courtesy of Julien Allaz- Univ of Colorado) for U, Th, Pb, Y and La:
(https://smf.probesoftware.com/oldpics/i42.tinypic.com/15hgbqv.jpg)
Note the "hot spots" in the Pb Ma high off-peak image from sulfur ka, which illustrates the necessity of the multi-point background method of Jercinovic and Allaz, which can dynamically avoid such off-peak interferences from unexpected elements. See this paper for further details:
http://probesoftware.com/download/BoT&A_Jercinovic.pdf
and here for more technical information on using multi-point backgrounds in Probe for EPMA:
http://smf.probesoftware.com/index.php?topic=56.0
After processing in CalcImage for background, matrix and interference (Y and La on Pb) corrections we obtain the following quantitative images:
(https://smf.probesoftware.com/oldpics/i44.tinypic.com/264s5cg.jpg)
Note that the Z values are in elemental weight percent values. By applying the method of Montel (from Allaz) we can calculate the chemical ages using this menu in CalcImage:
(https://smf.probesoftware.com/oldpics/i44.tinypic.com/ejiy4p.jpg)
We then obtain the U-Th-Pb age images as seen here:
(https://smf.probesoftware.com/oldpics/i42.tinypic.com/21ms021.jpg)
which reveal the chemical age (lower right), Pb from U (upper left), Pb from Th (lower left) and calculated Pb (upper right). The presentation output from the Project menu is seen here:
(https://smf.probesoftware.com/oldpics/i40.tinypic.com/nqdboo.jpg)
For some excellent discussion on quantification of monazite chemistry, please see this topic by Julien Allaz:
http://smf.probesoftware.com/index.php?topic=186.0
I should note that there are various terms for dating of monazites by EPMA but one term that seems appropriate is Chem Age. I sort of like EPMA Dating.