I just pre-production released on GitHub my NIST XCOM based java library to compute Compton, Raleigh, photoelectric and pair production cross sections.GitHub
It’s not a plugin or a macro so I’m not sure how else to share it. I used it mainly in ImageJ for modeling beam hardening in microCT images acquired with conventional x-ray sources.
The jar file, JavaDocs and a sample plugin are available on Google Drive
I hope this is helpful to the community. Since it’s the first time in the wild, if any one is interested in testing, your feedback will be much appreciated.