Possible Clues:

• M.D.'s diagnostic tool
• Source of some inside info?
• Oncology procedure
• Source of inside info?
• Foremost types among Centenary Toughie solvers have skill in 'beneath-the-surface' scrutiny
• Hartford market checker's action?
• MRI relative
• Medical imaging proc.
• X-ray computed tomography
• It might reveal more than a simple X-ray