Isotope profile
Lead-212
Pb-212 · Lead
Lead-212 works as an in-vivo alpha generator: a beta-emitting parent that feeds a high-energy alpha chain, packing mixed-LET radiolysis into a 10.6-hour half-life.
Public data & model inputs
Mixed chain- Half-life
- 10.6 hours
- Decay mode
- β⁻ → α chain
- Charged-particle energy per decay
- 7.69 MeV
- G(H₂O₂) yield
- 0.98
- Clinical use
- Targeted alpha therapy (TAT)
The radiolytic profile
Why Pb-212 is hard
Pb-212 works as an in-vivo alpha generator: the parent decays by beta, but its short-lived daughters deliver high-energy alphas, so the charged-particle energy per decay is dominated by that alpha chain. The mix of beta and alpha emission gives it a mixed-LET profile and a radiolytic yield above a pure beta's, dense alpha tracks and diffuse beta tracks in the same vial.
All of that is concentrated into a 10.6-hour half-life. At early-clinical activity the absolute peroxide burden is high: higher than At-211's, and second only to Ac-225 among the alpha-bearing isotopes modeled here. It builds fast while the source is live, and the source itself decays away within a day. The Pb-212 signature is mixed-LET intensity packed into a sub-day clock.
The modeled run
One clinical scenario, uncoated vs DuraRad
The run below models a representative Pb-212 targeted-alpha vial across two half-lives: uncoated, then with a DuraRad coating on the same geometry.
Scenario: 175 MBq Pb-212 · 10R/5 mL vial · 21.3 hours window (two half-lives)
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Modeled reduction in cumulative peroxide exposure
98.6%
Not a measure of drug protected
- Uncoated peak (upper bound)
- 181.6 µM
- DuraRad peak [H₂O₂]
- 2.75 µM
- Cumulative exposure (AUC)
- 2.37 mM·h → 0.033 mM·h −98.6% modeled
- Modeled peak reduction
- −98.5% 66x lower peak peroxide
Modeled from measured peroxide clearance in DuraRad vials and literature radiolysis yields. Radioactive validation designed and scheduled for Q4 2026 at Washington University in St. Louis.
Model & validation detail
Pseudo-first-order H₂O₂ clearance, k = 0.107 min⁻¹ (Batch 2, 6R / 3.0 mL). Generation from literature G-values. Performance under continuous irradiation not yet validated.
The DuraRad answer
How DuraRad protects this product
DuraRad lines the vial wall with a sol-gel coating holding immobilized manganese SOD and catalase. Radiolysis of water generates superoxide and peroxide throughout the solution; the fraction that diffuses to the wall meets the coating, where Mn SOD converts superoxide to hydrogen peroxide and catalase breaks that peroxide down to water and oxygen. Acting as a distributed sink at the wall, the coating lowers the steady-state concentration of superoxide and peroxide in the vial. The enzymes are immobilized in the coating rather than dissolved into the formulation, so they are not an ingredient in the dose. Clearing that superoxide and peroxide at the wall keeps their concentration low in the vial and lowers the oxidative burden on the drug.
Because Mn SOD and catalase turn over on a minutes timescale while Pb-212 stays live for many hours, the coating re-clears the vial many times across the source's active life, and in the model it holds peroxide well below the uncoated level. The alpha-dominated track structure drives a high per-decay peroxide yield, exactly the burden a wall sink is suited to draw down. This behavior is modeled, not yet measured; the Q4 2026 radioactive validation at Washington University in St. Louis is designed to confirm it.
Where it's going
Every Pb-212 dose is headed for a scanner or a treatment room, where arriving intact is the whole point.
Data & sources
Sources for this isotope
- Pastina & LaVerne, J. Phys. Chem. A (1999) LET dependence of hydrogen-peroxide yield in water radiolysis.
The full nuclear-data citation list for the roster is on the isotope index.
Keep exploring
More of the roster
Model Lead-212 against your own dose.
Open the simulator pre-loaded with Pb-212 and adjust activity, vial format, and fill volume, reserve coated vials to test on your own bench, or talk to us about your product.