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Donald W. Baker

Donald W. Baker was born in Skagway, Alaska in 1932. From 1951, he served for 4 years in the United States Air Force in the Korean War. He spent 2 years working at the Air Force Cambridge Research Center investigating the detection of low-flying aircrafts and airborne bombers basing on returned radar signals. During his Service he was able to acquire knowledge on various electronic applications and in particular those concerning the different types of radar devices. Discharged from the Air force in 1955, Baker entered the University of Washington, Seattle and graduated BScE from the Electrical Engineering Department in 1960.

The continuous wave doppler method, however, did not provide explicit information about the distance between the ultrasonic transducer and the moving target. Baker saw an article on the study of the motion of snow and raindrops in the clouds using a pulsed-doppler radar which inspired him to start working on pulsed-doppler instrumentations. The initial device was of a phased-coherent pulsed-doppler design with a reference frequency transmitting a sample of the doppler signal into the target tissue and comparing the relative phase to give a phased-modulated signal at a particular depth of the vessel that can be range-gated to obtain flow and positional information at that particular sample volume. Baker published the landmark articles: "A phase coherent pulse Doppler system for cardiovascular measurement" in 1967 followed by "Pulsed Ultrasonic Blood Flow Sensing" in 1969.

Between 1973 and 1974 Baker effected a technology transfer of the doppler instruments to a newly-founded (1969) Seattle company ATL (Advanced Technology Laboratories, Bellevue, WA). Howard Suskin, founder of the United Control Corporation was the entrepreneur behind the business venture, the technology being introduced to him and his engineer partner Ralph Astengo by Baker and his wife Joan, who was a sonographer. "Technology transfer", rather then simple transfer or licensing of 'patents' included a range of formal and informal co-operations between the technology developer and commercial enterprise. In addition, technology transfer involved the transfer of knowledge and technical know-how as well as physical devices and equipment. By agreement, the University of Washington also received from ATL® a sum of money each year for a number of years, basing on sales revenue.

ATL® started with 3 engineers and the first ATL pulsed doppler scanner appeared in the fall of 1974. The Mark I was soon commercially available in 1975. The 400B pulsed-doppler developed slightly later became part of the well-known ATL Mark V duplex scanner which debuted in 1978. Duplex doppler was in fact way ahead of its time and most physicians did not know what to do with it. A lot of ground data would need to be built. Baker realized that in order to sell the duplex doppler to the cardiovascular physicians they would need a better M-mode in their instruments. This was done after bringing in new engineers in applied physics and ATL soon boasted in their machines some of the best M-mode functions and traces that was available at that time.

Baker travelled extensively around the world in 1980 to hold seminars and to promote the duplex devices. ATL produced the Mk 300 and 500 in '80 and '81 respectively (followed by the MK 600 in '82 and the MK 100 in '83). The Mk 500 and 600 had probably the best real time duplex doppler at that time.

In 1970, Donald Baker was married to Joan Baker, who was founder & first president of the Society of Diagnostic Medical Sonographers ( SDMS) in the same year and first chair of the American Registry of Diagnostic Medical Sonographers (ARDMS). Donald Baker retired from the University of Washington in 1979 and subsequently was out of the Ultrasound field in 1984. Prior to that, he was a full-time consultant to Squibb Medical Systems®, the International division of ATL and had taught in numerus seminars on the application of doppler ultrasound. Among other accolaides he was given the Pioneer award from the AIUM in 1987 and the Pioneer Award from the Society of Vascular Technology in 2000. Baker holds a number of important patents and has authored over 30 articles and book chapters on Ultrasonic Instrumentations. A few of his original continuous wave doppler and the pulsed-doppler devices are now exhibited in the Smithsonian Museum of American Medical History.

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