Version 4 of the 3D Slicer application, created and supported by NAC for nearly two decades, has surpassed the 260,000 download milestone since it was released in 2011. The most recent version 4.6.2 has been downloaded at a rate of over 290 downloads per day in the first two and a half months of 2017, with a clear trend toward steadily a steadily increasing download rate. These download statistics are evidence of the worldwide impact of the free and open source 3D Slicer software and the valuable part it plays in enabling science and clinical research across a range of...