This talk will discuss how Image Guided Technologies (IGT) in Boulder, CO, used ODRPACK to locate significant calibration discrepancies within their coordinate measuring machine. This instrument is employed in the design and manufacture of 3D optical localizers that enable surgeons to track the location of a probe inserted into a patient's skull. The development of novel optical property models was efficiently facilitated by application of ODRPACK, and accuracy testing and certification of new IGT systems are presently performed using procedures based on ODRPACK. Some specific features of ODRPACK that make it especially relevant for high precision measurements and uniquely well-suited for modeling 3D image data will be described.