Calibration certificate of a radium preparation delivered to the Netherlands Cancer Institute in 1915, tested in the Institut du Radium in Paris and signed by M. Curie
In 1915, 100 mg of radium was delivered to the Netherlands Cancer Institute in the form of plaques and needles. A detailed listing of the cost is missing from the NKI archives. However, the calibration certificates from the laboratory of Marie Curie in Paris have been kept. Historical prices of radium are listed in an item in 1911 on this timeline. The price of 100 mg of radium in 1914 can be estimated at US$ 16,000. The conversion US$ to Dutch guilders in 1914 is 1:2.46 . On the basis of this information, the price of 100 mg radium in 1915 is approximately ƒ39,360
From the annual financial report of the Netherlands Cancer Institute (NKI) in 1915 , it appears that the actual price of the radium must have been lower. This is not clearly mentioned, but for an amount of ƒ30,500 both the radium and the X-ray unit were purchased and the operating theatre was equipped. The purchase of the radium was certainly the most costly item of the equipment of the clinic in 1915. In the NKI, 100 mg radium in 1914 did not cost much less than the running costs of the clinic and the laboratory together over the whole year. The budget mentions salaries at ƒ18,697, housekeeping ƒ13,402, instrumentation, chemicals and dressings ƒ3,207 and general costs ƒ1,168 for a total cost of ƒ37,074.
In comparison to this, the cost of the X-ray unit which was bought by the NKI in 1914 was low. In the catalogue of manufacturer Reiniger Gebbert & Schall  the price of the X-ray unit in German gold marks was 2,350. The value of the German gold mark in 1914 was 0.5775 Dutch guilders .
In 1914 the historical price of the first x-ray apparatus in the NKI was about ƒ1,357, so the purchase of 100 mg radium in 1915 was a very large investment. This underlines the importance of radium which, during the first years of radiation therapy, was the principal means for the irradiation of tumours.
Radium contamination on a certificate signed by Marie Curie in 1914, shown by autoradiogram
The radium that was ordered by the NKI in 1914, was checked before delivery for purity and concentration by the laboratory of Marie Curie in Paris. The certificate is still (2013) kept in the Antoni van Leeuwenhoek hospital.
In 1995, physicist Harm Meertens discovered that the certificates of 1914, which were signed by Marie Curie herself, are contaminated with radium. For his test he used a so called autoradiogram. The document has been placed for a long period on an X-ray film. The fingerprints (upper half of the paper) and palm (right below) of Marie Curie are visible from when she rested her hands on the certificate while signing. It can be assumed that her body was contaminated, which was not surprising during the early years when primitive measuring equipment could probably not detect a slight radium contamination. This contamination is strong enough to expose the film after 100 years. With a mass spectrograph it has been confirmed that this is indeed radium contamination.