Phantom studies have been performed. Preliminary studies have been published and a comprehensive assessment of dosimetric parameters is in preparation. Limited clinical assessment is underway to determine the day-to-day utility of this system as compared with conventional in-vivo measurement methods.There is a follow-on three phase project to develop a detector array for dose-guided radiotherapy, or DGR. Phase I is to develop an array of fibers as either a rectangular or spiral grid and study the dose map generated during radiotherapy and the effect of small changes in organ or beam positioning. Phase II is to understand the meaning of signal change relative to the patient's anatomical position and to interrupt the treatment if detected signals differ from reference values by a predetermined tolerance margin. Phase III is to dynamically link the changes in grid signals to corrective changes in the radiation field for on-line, dynamic dose control of radiation treatments.