Many Nobel Prizes are awaiting good research to understand and explain the many mysteries of our bodies, such as the basic mechanism of memory or imagination.
When I entered medical physics in 1958 there were fewer than 100 in the U.S. and I could see many opportunities to apply my knowledge of nuclear physics.
Nuclear physics is interesting but it is unlikely to help society.
In 1970 I realized that there was negligible risk from x-rays but many radiographs had poor image quality so that the risk from a false negative was significant.
In some cases radiation reduces the incidence of cancer.
We developed simple test tools to optimize imaging parameters. No company was interested in our idea.