One of the most likely risks astronauts on long duration space missions face is exposure to ionizing radiation associated with highly energetic and charged heavy (HZE) particles. Since access to medical expertise on such a mission is limited at best, early diagnosis and mitigation of such exposure is critical. In order to accurately determine the dosage within 1 hour post-exposure, dose-dependent biomarkers are needed. Therefore, we performed a dose-course transcriptional analysis for radiation exposure at 0, 0.3, 1.5, and 3.0 Gy with corresponding time point at 1 hour (hr) post-exposure using Affymetrix GeneChip Human Gene 1.0 ST v1 Array chips. The analysis of our data suggests a set of sensitive genetic biomarkers specific to each radiation level as well as generic radiation response biomarkers. Upregulated biomarkers can then be used within lab-on-a-chip (LOC) systems to detect exposure to ionizing radiation. A total of sixteen human samples representing radiation exposure at levels 0 Gy, 0.3 Gy, 1.5 Gy and 3.0 Gy at time point 1 hour (hr) post-exposure were constructed. Blood samples were extracted from four human volunteers, and were irradiated. Leukocytes were extracted, and gene expression was measured. Samples for all four volunteers were measured at 1 hr for all four dose levels, resulting in four replicates at each dose level. Thus, a total of 4 samples at each of the four radiation levels were sampled, yielding the total of 16 samples.