All phantom studies with the existing prototype detector system have been completed. The system was also used successfully to measure the output factor of newly acquired stereotactic applicators with very small apertures. The measurements were validated with Monte Carlo calculations as well as with radiochromic film. This project has reached its until a commercial prototype is produced. The original company selected for this task was unable to complete such a unit in the allotted time frame and has defaulted on the terms of its agreement. NRL is in the process of selecting a new company, but until this is done and the new company can produce a workable unit, this project cannot progress further. Once this happens, there are 2 additional follow-on projects: (1) a 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. (2) a separate project to develop a film-based OSL dosimeter as a replacement for photographic film for dosimetry measurements. Preliminary measurements using ground OSL glass dispersed on a film substrate with a binder were promising, but better methods must be found to produce OSL particles that are uniform in size. One possible approach is to employ nanoparticles incorpoprating OSL molecular chains, and we are currently partnering with an academic institution to explore this possibility.
