Theta radiation, also known as theta-band emissions, is a radiation emitted by contaminated antimatter byproducts. Theta radiation poisoning is extremely dangerous to the health of humanoids. One of the first symptoms is hallucinations. The final stages of theta radiation poisoning involve the degradation of major body organs.

Theta radiation in small doses can be used to destroy microorganisms, and was used in decontamination chambers.

Theta radiation can impede sensor scans. High enough concentrations can disrupt subspace, collapsing the warp fields of nearby starships.