Experimental 1 MV X-ray machine installed by Philips

Millionair kelder met Hoed en Wassink.jpg 

Daniel den Hoed (l) and Willem Wassink in an inspection trolley up at the ceiling of the cellar, next to the 1 MV X-ray tube. Photo Philips Company Archives. 

In 1939, Wassink and Den Hoed set up a new collaboration with Philips. Under the leadership of Dr. Albert Bouwers, the X-ray group in the Philips research laboratories (known as the "NatLab") developed a machine with a maximum acceleration voltage of 1.2 million volts. The machine is installed in the Netherlands Cancer Institute (NKI) [32]. 

The Philips Research Laboratory built  a variety of these machines. A 400 kV radiotherapy machine is installed at the university hospital in Groningen, and 1.25 MV and 2 MV experimental machines are installed in the Cavendish Laboratory in Cambridge, England [33, 34]. These latter machines are used for physics research in connection with the development of nuclear bombs in the second World War when the team of Professor Rutherford in the Cavendish Laboratory cooperated with the laboratory at Los Alamos in the USA.

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Sketch of the setup of the "Millionaire" as it was called, in the NKI in the Sarphatistraat. Photo Philips Technisch Tijdschrift.

In the cellar stand two cascade rectifiers each of around 600 kV.  They are connected to a 1.2 MV X-ray tube which is installed up at the ceiling.  The machine produced beams in three directions simultaneously through openings in the floor above, so that several patients could be treated at the same time.  The positioning of the beams coming up through the floor was particularly difficult and inaccurate.

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Photo: Dr. Daniel den Hoed discharges a 600 kV cascade generator in the cellar of the NKI.Spaarnestad Photo

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Below: Control panel of the "Millionaire" with radiation therapist Lyda Wallach-Elte, a photo from 1953 immediately before the decommissioning of the machine. Photo Mrs. Wallach-Elte

Running along the floor underneath the control panel, rails disappear behind the movable shielding panel. Originally, these rails carried the prepared patient on the treatment bed into the radiation room (see the sketch above). On the right, three levers operate the lead trapdoors through which the radiation beams are directed. In this way, the treatment time for an individual patient could be determined. The output was small, about 20 r/min, which made the irradiation time long. During the irradiation, the high voltage was checked using a small telescope (see this hanging at far right) to look at the meter through a small hole in the floor.

The radiation therapist in the photo is Lyda Wallach-Elte.  In 2008, Henk van der Gugten interviewed her about the radiotherapy department during the period 1950 to 1960.  A family friend of the Wallachs, the photographer Sem Presser, made a photographical report on the work and equipment of the Radiotherapy Department that provides us today with clear pictures.


Bronnen & Publicaties

  • [32] Philips Technisch Tijdschrift (Philips Technical Journal), jg4, nr6, juni 1939: Een röntgenbuis voor 1 millioen volt, door J. H. van der Tuuk. ,
  • [33] Philips Technisch Tijdschrift (Philips Technical Journal), jg2, nr6, juni 1937: Een generator voor zeer hoge gelijkspanning, door A. Kuntke. ,
  • [34] Notes Rec. Royal Society London, 35 (1), p 121-134 (1999): The Cavendish High-Voltage Laboratory 1935-39. Bij W E Burcham. ,