Today I will write about the modern ages, from WWII until 2000's with the focus on the development of molecular biology methods as well. Considering the radium, until recently, the logic was "wack them all".
Cell cultures became popular somewhere between 1940 and 1950 thus at the time it was easier to work with the whole animals.

Plus we should keep in mind that the radium and the radioactivity at that time was a bit "hype".

I tried to find when the MTT (cytotoxicity) test was discovered but it came after radioactive-based assays, thus it also must be after WWII. Probably they intentionally tried with something that kills all the cells. And they tried to "localize" the effect by using those needles.

Part II will be much more interesting.

Thanks for support! :)