For computational efficiency or mere simplicity, it is common to approximate a multidimensional radioactive system with an "equivalent" one-dimensional spherical system. Uncollided decay gamma-ray leakages and neutron-induced gamma-ray leakages from simple multidimensional source/shield systems were compared with those from similar spherically symmetric systems. Maintaining the location and thickness of a flat or cylindrical shield, but making it a sphere, leads to large errors when the shield is close to the source. The spherical shell at the same location as the multidimensional one that was most equivalent, in terms of providing the best match to the line leakages, was up to 23% thinner (decay gamma rays) or 50% thicker (neutron-induced gamma rays).