In 1946, Dunmore Dunk and Zed Atlee co founded Dunlee. The title Dunlee is a separation of the names of two founders, along with their respective resources and advantages. They successfully developed and manufactured radiation imaging tubes, and successfully entered the high-end CT tube market until today.

In 1994, Dunlee's headquarters moved from Bellwood, Illinois to Aurora, Illinois, which also has a 162000 square foot design and manufacturing center.

In 1998, Dunlee pioneered the CT tube replacement market and produced the industry's first 1.0 MHU CT exchange tube, which was also a CT replacement tube.

In the past, the CT replacement tube used to cover up the products of major manufacturers such as GE, Philips, Siemens, Canon, etc.

In 2001, Dunlee was bought by Philips. Philips Medical's CT replacement tube is a guide in the field of medical imaging, especially in X-ray tube technology. As early as 1895, Philips manufactured the first commercial X-ray tube. Afterwards, Philips achieved many technological achievements in the field of ball tubes, such as the liquid metal bearing technology created in 1990, which made X-ray ball tubes used in cardiovascular and CT equipment almost noiseless and would not fail due to traditional ball bearing wear.

After buying Dunlee, Philips Medical consumes over 12000 tubes annually.