Evaluation of radiation damage effects of low-energy Auger and conversion electrons emitted by 134Ce decay using a Monte Carlo method

Abstract

Abstract Targeted radionuclide therapy (TRT) is a cancer treatment method that delivers radiation to specific tumor cells, enabling efficient tumor cell killing. Radionuclides emitting short-range beta or alpha particles have previously been the primary focus. TRT approaches utilizing low-energy electrons, such as Auger and internal conversion electrons, have attracted interest because of their highly localized tumor-killing potential. 134 Ce is an imaging surrogate in the form of a 134 Ce/ 134 La pair for positron emission tomography (PET) imaging in 225 Ac targeted alpha therapy, and it has recently exhibited promising therapeutic properties. This study employs TOPAS-nBio, a Monte Carlo simulation tool, to investigate the radiation damage effects of 134 Ce from dosimetric and DNA-scale perspectives. The DNA damage yield analysis incorporates both physical and chemical processes. In the water sphere geometry, the overall dose contribution of 134 Ce shows patterns generally similar to those of other Auger-emitting radionuclides, and 134 Ce shows damage yields per decay close to those of 161 Tb on the DNA scale. Although 134 Ce induces fewer DNA double-strand breaks per decay in the nucleus than 125 I and 161 Tb, it exhibits a higher double-strand break yield when normalized to absorbed dose. Such damage outcome predictions suggest that further research on radionuclide therapy using 134 Ce is worthwhile.