Described herein are liposome-based nanocarriers that selectively target bone marrow, minimize tumor delivery, and maintain high drug concentrations in bone marrow when compared to conventional systemic delivery. The composition of the liposome-based nanocarriers may also be tuned to selectively target lymph nodes and other reticuloendothelial system organs (e.g., spleen, e.g., liver). Also described herein are methods of imaging and mapping the bone marrow and/or other reticuloendothelial system organs using the described liposome-based nanocarriers. These methods provide high resolution non-invasive and quantitative imaging via PET, which offers advantages over conventional imaging/tracking methods. Furthermore, in certain embodiments, the liposome-based carriers are used to stabilize and deliver radioprotectant/free radical scavenger drugs to the bone marrow, thereby protecting the bone marrow from subsequent radiation exposure, thereby limiting the adverse impact of radiation exposure on the individual.