Technegas was the name coined in November 1984 to describe what we now know to be a specialised sub-set of nano-encapsulated carbon composites. Technegas is inhaled as the ventilation component of a two part, Ventilation/Perfusion, (V/P or V/Q), radio-diagnostic test for blood clots that have lodged in the lung - Pulmonary Embolism (PE or PTE).

Technegas, as produced in a purpose-built apparatus, consists of hexagonal flat crystals of Technetium metal cocooned in multiple layers of graphite sheets, now known as ‘Graphene’,  completely isolating the metal from the external environment.  Created in an inert atmosphere of Argon, it is inhaled in a few breaths, prior to imaging its distribution in the lung.