Heterogeneity in the response of cancerous tumour tissue to ionizing radiation is well-established in the scientific literature, though not at all well-understood. We take some initial steps towards this understanding by considering cell-size measurements on radiochromic film (RCF) that has been exposed to varying levels of ionizing radiation, and comparing the observed spatial heterogeneity therein to what would be expected via Monte Carlo simulation under similar conditions. We describe the process of distilling high-dimensional measurements obtained through Raman spectroscopy on a grid of RCF to a low dimensional grid representation of dose deposition. Then we obtain spatial heterogeneity scores on this grid, along with the grid of simulated values, and provide arguments correlating the two results. We also provide context on experimental work currently under development that we will apply similar processes to, foreshadowing the potential of significant scientific findings on radiation response at a cellular granularity.