The photo shows the radiotherapy treatment room in the Netherlands Cancer Institute at Keizersgracht 706, Amsterdam. The treatment machine has been transferred from the teachning hospital in Amsterdam, the Binnen Gasthuis, where Dr. Gaarenstroom used it from 1914. The machine is an "Apex-Spezial-Röntgenapparat für Intensiv-Tiefenbestrahlungen" manufactured by Reiniger Gebbert & Schall of Berlin (D). The tube voltage is estimated to be 100 kV.
The high voltage range for the x-ray tube was 80 to 140 kV. The only direct "measuring equipment" for this was a so-called spark gap: a discharge passed between a sharp point and a plate when the required voltage was reached. After adjustment of the distance between these two points to approximately 26 cm, the high voltage was increased until the spark was produced. The spark gap is mounted on the two insulators to the right on top of the high voltage cabinet. On the right hand insulator an adjustable pin with pointed tip is attached, barely visible here. On this insulator, there is also a mA meter for measurement of the tube current. On the left hand insulator the metal disc of the spark gap is attached. A hardness meter of the Bauer-system* type is hanging from the ceiling. The double cathode insulators to the left of the cabinet show that the unit has been converted for the use of Coolidge type X-ray tubes and is fitted with a filament supply. But for the majority of treatments in 1915 the ion gas tubes were still used.
The high voltage was connected to the tube with unshielded cables which the physician had to manipulate with great care. The equipment was barely shielded and the radiation exited from the X-ray tube in many directions. The physician, who stayed next to the patient during the treatment to operate the machine, also received a small dose.
Besides an X-ray unit, the NKI also has 100 mg of radium, divided over various applicators. In particular, so-called plaques and tubes were used. Radium plaques with a radiation strength of 2.5, 5 or 10 mg of radium were placed on the area to be treated (the drawing of the plaque is kept in the Historad archive of the Department of Radotherapy; the two photos are examples from other locations.
Neck mould in which radium sources are placed for a neck irradiation
* see the item "Measurement and Control of X-rays"