False-colour gamma camera scan of the human kidneys, revealing an infection in the right kidney (right on this posterior incidence image). Gamma camera imaging using the radioisotope Technetium-99m (99mTc) linked to dimercaptosuccinic acid (DMSA), a compound fabsorbed by the kidneys, is used to obtain a comparison of their relative function. In this image, reduced function of the right kidney is indicated by decreased activity, represented in shades of purple, compared with the normal left kidney.