Precision oncology enables individualized treatment decisions on the basis of patient - and tumor-specific features. Despite growing evidence that inter-patient variation in tumor genomes affects treatment responses after radiation therapy, patients receiving these treatments continue to be treated with the same or similar doses. Herein, we discuss past, contemporary, and potential future forays into the mapping of the radiogenome of humans and their tumors. We contend that the incorporation of genomic information into radiation treatment approaches represents a critical step toward the individualization of radiation dose, which considers both treatment-related toxicity as well as tumor control probability. Specifically, we describe the role of somatic and germline genetic features on radiation tumor sensitivity and normal tissue toxicity. We also discuss potential barriers for the implementation of genomic predictors in clinical practices and strategies to overcome these barriers. The following discourse seeks to inform and guide the future use of genotype-directed radiation dose delivery and targeted radiosensitization.