Ace the Nuclear Cardiology Boards 2026 – Radiate Confidence and Success!

Gamma camera collimators work by only allowing photons that travel nearly parallel to the holes to reach the detector, so the surrounding material must strongly attenuate photons coming from other directions. Lead is the material of choice because its high atomic number and density provide very efficient gamma-ray attenuation, allowing relatively thin walls to block unwanted photons while preserving the holes through which desired photons pass. This balance is especially important for common nuclear medicine energies, like 140 keV from technetium-99m, where lead walls can be designed to optimize image quality without making the collimator impractically heavy or thick. Aluminum, steel, and plastic don’t attenuate gamma rays as effectively, so they either require much thicker sections or would produce higher background and poorer resolution. While other dense materials like tungsten exist, lead remains the standard due to its combination of attenuation efficiency, workability, and cost.