Novel optical technologies can provide detailed microscopic information about tissue structure and physiology in a noninvasive manner, without patient discomfort. This otherwise unobtainable information can help the physician in selecting the best treatment, thus greatly benefiting the patient. For example, it can be used for early disease detection, resulting in more effective treatments and higher cure rates. It can also provide detailed understanding of the progress of various therapies to ensure that they are working, and to enable their improvements for increased effectiveness. We will concentrate on the latter direction in this research, by using state-of-the-art optical methods to monitor tissue changes caused by X-ray cancer treatments. Specifically, a new imaging technology based on spectroscopic and textural optical coherence tomography (s/tOCT) will be developed and applied to examine X-ray irradiated normal and cancerous tissues. The goal of this project is to develop and quantify reliable and robust s/tOCT signal 'features' that result from radiation treatments. Such analysis in both tumour and in surrounding normal tissues should provide early indications of radiation therapy response, and yield valuable insights into the mechanisms of radiation damage ('what happens, where, and when'). These changes, once quantified and validated, can help optimize and personalize radiation treatments, with ultimate clinical implementation made possible by the compact, practical and robust nature of OCT 'photonic' technology. Patient-specific individualized irradiations can then become feasible. This may improve the effectiveness of radiation therapy (a widely used cancer therapy technique) and may help in use/choice of other treatments (e.g., adjuvant chemotherapy), with potential to yield more cancer cures and reduce patient suffering.