Chapter 3: Mathematics of Nuclear Decay

The previous chapter discussed the physical processes of the nuclear decay of unstable isotopes, including electron capture, beta-minus decay, beta-plus decay, and other decay modes. This chapter considers a mathematical description of that decay. To appreciate why this is important, consider the decay of 125I into tellurium (Te), which occurs via electron capture. This isotope is used in low-dose rate brachytherapy treatments for prostate cancer and other applications. To calculate the dose in such an application, one needs to know the amount of radioactive 125I that is present after a certain amount of time (more material results in a higher dose rate). This chapter presents a mathematical framework for understanding this.