Gallium-68

Ga-68 decays with a 68-minute half-life, which means the entire radiolytic dose is delivered as a short, intense burst rather than a slow release. The positron is fairly energetic, comparable to Y-90's beta, but at the PET-imaging activity Ga-68 is used at, the absolute hydrogen-peroxide concentration a vial reaches stays low, on the micromolar scale.

That short half-life is exactly what makes Ga-68 the hard case for any clearance-based approach. The peroxide arrives faster than an enzyme layer can fully remove it, so the modeled coated and uncoated curves stay much closer together than they do for the multi-day therapeutics. Ga-68 is front-loaded and brief: a burst, not a burden that lingers.

DuraRad lines the vial wall with a sol-gel coating that holds immobilized manganese superoxide dismutase and catalase. The enzymes stay bound to the wall rather than dissolving into the dose, so they act as a distributed sink: the superoxide and hydrogen peroxide generated by radiolysis throughout the solution are consumed as they diffuse to the coating, with SOD converting superoxide to peroxide and catalase decomposing peroxide to water and oxygen. This clears the superoxide and peroxide as they form, keeping their concentration low and lowering the oxidative burden on the tracer. It is the same clearance mechanism modeled for the long-lived therapeutics, here run against Ga-68's fast 68-minute burst.

Consumption at the wall works on a timescale of minutes, which matters most when an isotope releases its dose over days and the peroxide concentration has time to build toward a steady level the sink can hold down. Ga-68 is the opposite case: its 68-minute half-life front-loads the entire radiolytic dose into a short, low-LET positron burst, and at PET-imaging activity the peroxide a vial reaches stays on the micromolar scale. Because that dose arrives inside roughly one half-life, the peroxide accumulates faster than the wall can draw it down, so the modeled coated and uncoated curves sit closer together than for any other isotope in the roster. The suppression the model shows for Ga-68 is real but the smallest we report, and this is exactly the edge case the Q4 2026 radioactive validation at Washington University in St. Louis is designed to measure. These figures are modeled and not yet experimentally confirmed.