Laying the foundation for the new radiotherapy department in 1952. In the muddy soil under Amsterdam this implies driving of many supporting piles down to sandbanks that lie as deep as 15 to 20 meters below the surface.
The construction work for the new building of the radiotherapy department starts in 1951 and on 10 October 1953 the building is formally opened. The construction was carried out in 2 phases. The first phase includes a central waiting area around which separate radiation rooms for the orthovoltage (kilovoltage) equipment and a radium room are built. The second phase includes an isotope laboratory and a megavolt treatment shelter. The building of phase 2 is postponed until the choice for the megavolt equipment is made.
Thanks in part to the help of the Queen Wilhelmina Fund (KWF, the Dutch Cancer Society), granting an amount of f 40.000. - (Guilder, the former Dutch monetary unit), it was possible to construct a new department for radiotherapy, which would be opened on 10 October 1953. Construction and decoration costs amount to f 370,000. -
(From a report of the radiological therapy department)
"The most important events in these years are related to the construction of the new Radiology Department, a job that in fact started in 1946 (the rebuilding of the X-ray diagnostic department). The year 1951 was when the numerous ideas came to fruition; 1952 was the year in which - led by the architect, Mr I. BLOMHERT - the construction work started for the new radiotherapy wing of the department. The design presented us with problems, since at that time, while postponement of construction was not an option as winter was approaching, important information about the radiation equipment was not yet known."
At the end of 1953, the construction of the radiotherapy department is completed. An expansion is realized in which the patients can be received in a pleasant environment, and in which every radiation machine is set up in a separate room. There are also rooms for the isotope laboratory, the physics laboratory, radium room and offices. Two experimental X-ray machines are installed which will be used for dynamic treatment techniques.
1953, floor plan of the new radiotherapy department.
On the left there is a connection to the diagnostic facilities, surgery department , the hospital and the main entrance. On the right the first megavolt treatment shelter which is built in the second phase. It is designed for the new cobalt machine that will come into use in 1961.
Radiotherapy equipment in 1954. In 1954, the equipment for radiotherapy consists of a Philips type TU 1 rotating X-ray machine (dynamic treatment), a Siemens "Konvergenz" converging X-ray machine, a Philips stationary X-ray unit for 250kV/25mA deep-therapy, a Philips contact machine 50 kV, a General Electric Maximar-100 and a Philips Endotherapy 100 kV machine. A Philips universal dosimeter was ordered for the measurement of the dose rate in body cavities.
Physicist Hubertus Wijcker develops a method for the dosimetry of rotation treatment on the Philips TU1 unit. Isocentric rotational treatment was introduced on the TU1 machine on an experimental basis 
Dr. Lokkerbol introduces the central registration of treatment data of each individual irradiation. On the photo are dr Lokkerbol (right), and managing director of the NKI Drs. A. S. L. Spoor.
In the wall panel behind dr Lokkerbol are two recorders which print the setting data (applied high voltages and current, applied filter, radiation time etc.) of every individual treatment on one of the therapy machines in the department. Lokkerbol designed the registration system in cooperation with the physics department of the Netherlands Cancer Institute.