AbstractA new approach is applied to correlate different phases of the HeLa cell S-3 with mean lethal ionising radiation dose (Do) along with nuclear magnetic resonance water-proton spin-lattice relaxation time (T1). This information can be used to pin-point the mitotic phase of the cells in vivo. This enables us to apply ionising radiation treatment at that particular time. This will increase the efficacy of radiation treatment in cancer patients.