In this study, bone tumor cells were treated with a type of radiation called ^153Sm-EDTMP. By using electron microscopy, scientists saw changes in the cells that suggest they were undergoing a process called apoptosis, which is like programmed cell death. The cells showed clumping of genetic material, breaking up of the genetic material, and the formation of small structures called apoptotic bodies. When the researchers checked the DNA in the cells, they found that it was breaking into smaller pieces more as the radiation treatment continued. This shows that the radiation treatment could make bone tumor cells go through apoptosis, which is a way of disposing of damaged cells.