In order to deliver precise radiation treatment to the patient, we installed a cavity chamber inside a phantom. Then, a Cobalt-60 machine was used on the phantom and the measured charge per unit mass was equal to $3.024 \times 10^{-3}$ C/kg. Based on this information, calculate the absorbed dose of the phantom (in Gy). Note $W_{air} = 34$ eV, $S_m/S_g = 1.11.$