Gated Optical DetectorsDose Guided Radiotherapy

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Phantom studies have been performed. Preliminary studies have been published and a comprehensive assessment of dosimetric parameters is in preparation. The commercial prototype is due to be delivered in mid September for evaluation. There have been several delays at the company due to changes in personnel and shifting priorities. The prototype will be a 1-channel system. After we have assessed performance, the plan is to press for a multichannel (4-8 channels) system that would be more suitable for clinical use. 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. There is also a separate follow-on 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.