The Isotope menu controls all aspects of the use of isotopes.

• Use I-125... - opens the inventory dialog with I-125 as the default filter. Other isotopes can be selected from the dialog.
• Use Ru-106... - opens the inventory dialog with Ru-106 as the default filter. Other isotopes can be selected from the dialog.
• Select Inventory File - select the active isotope inventory file.
• Create New Inventory - creates a new, empty, untitled inventory.
• Save XXX.invy as... - save the current inventory as a disk file.