Rh123 is used for only cell viability/live or dead as in sperm and big cell such as cervical cancer cells. For detecting or quantitative measurement of ROS accumulated in the cells, use DC-FDA fluorescent dye. The binding of each dye differs.
I agree with Sand Ho Lee. To use Rhodamin 123 is possible but we have made much better experince with H2DCF-DA. See http://www.sciencedirect.com/science/article/pii/S2211124712003452?via%3Dihub