In 1917 at the Nat Lab (Physics Laboratory) Philips begin to repair x-ray tubes. One year later the first Philips x-ray tube is demonstrated. From 1919 onwards small series of these tubes are manufactured in the Nat Lab.
In 1920 Albert Bouwers start to work on x-ray technology at the Nat Lab. Since then, he and his group have had an enormous contribution to the development and application of x-ray technology. Bouwers left Philips in 1941 to become the first director of Oude Delft (Old Delft).
It is Bouwers group that developed the first x-ray tube which is shielded for unwanted radiation. The cylindrical tube envelope consists partly of glass and a ferrochrome alloy. The Metalix x-ray tube is introduced in 1925.
The next step to take is to develop a x-ray tube which is also electrical safe. In 1928 the Metalix Junior is introduced. It is the first x-ray apparatus fully protected for high voltages and unwanted x-ray radiation.
Because of fast movements of the lungs, short x-ray exposure times are needed to become sharp x-ray images for diagnosis of tuberculosis of the lungs. Therefore the load of the focal spot has to be increased. To accomplish this, the Rotalix Metalix is introduced by Philips in 1929. It is the first x-ray tube with a rotating anode. All current x-ray tubes do have a rotating anode.
Also dentists start to apply x-rays for diagnosis. Especially for this kind of applications ease of use is very important. In 1947 the Oralix dental unit is introduced by Philips. At that time the smallest x-ray unit. For years it is the standard for this application.
The invention of the x-ray image intensifier is a major breakthrough in x-ray technology. The increased brightness of the x-ray image opens the way to new applications. In 1952 the first 5” image intensifier in Europe is introduced by Philips.
After the introduction of the image intensifier, all kind of new applications were looked for. In 1954 the BV20 is introduced by Philips, a complete new dedicated x-ray apparatus for use in operation theaters.
Dr. Albert Bouwers (1893-1972).
He has written four books and a large number of articles about x-ray technology, high voltage technology and optics. His name is on more than 200 patents and he received a number of very important scientific awards.
The Metalix D tube with a water cooled anode and inserted in a tube housing. The middle part (ferrochrome alloy) of the tube envelope is covered with a lead layer in a chrome cylinder. The glass parts of the tube envelope are covered with cylinders made from Philite, a very good electrical insulator. The x-rays can leave the tube via a small glass window in the ferrochrome cylinder of the tube envelope. The Metalix Junior apparatus is a Metalix D tube with air cooling, connected with fully electrical shielded high voltage cables to a small high voltage generator. The apparatus has a fixed high tension of 60 kV and a fixed tube current of 5 mA. The size of the focal spot is 1,5 mm.
A Rotalix Metalix x-ray tube inserted in a tube housing. The anode is made of a cylindrical copper block with a disc encased with spiral shaped tungsten for the focal track. It is powered with an induction motor rotating with a speed of 2800 revolutions/min. The focal spot load is increased with 4 to 6 times. A first prototype of the Oralix is shown in 1937 in Chicago. Because of design problems and the second world war it takes until 1947 the delivery of the unit start. In the unit a very small (6 cm long) x-ray tube is used. The wires used in the transformer do have a diameter of only 30 micro meter. That is why the unit is very small and has a weight of only 4,5 kg.
The first Philips x-ray image intensifier. The diameter of the entrance screen is 5”. Electrons released by photo emission in the entrance screen are accelerated and focused on the smaller phosphor output screen, resulting in a much brighter x-ray image. To view the image at the output screen, optical means are used . A few years later a television camera is coupled to the output screen. The First BV 20 (BildVerstärker, image intensifier; 20 mA). It is a revolutionary design and it takes until 1959 for other companies to come up with such a system. The first system is equipped with an optical viewer, which will be replaced by a x-ray television camera a few years later.