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Title: Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm{sup 3+}) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405 nm to erase the recorded dose information in Sm{sup 3+}-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm{sup 3+}-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm{sup 2+} to Sm{sup 3+} reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm{sup 2+} to Sm{sup 3+} reconversion process, the capture of these electrons by POHC (and hence theirmore » disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT.« less
Authors:
; ; ; ;  [1] ; ;  [2] ; ; ;  [3] ;  [4]
  1. Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada)
  2. School of Chemical and Physical Sciences and MacDiarmid Institute, Victoria University of Wellington, Wellington 6140 (New Zealand)
  3. Canadian Light Source, Inc., University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada)
  4. Saskatchewan Structural Sciences Centre, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9 (Canada)
Publication Date:
OSTI Identifier:
22278059
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 36 MATERIALS SCIENCE; 62 RADIOLOGY AND NUCLEAR MEDICINE; DOPED MATERIALS; ELECTRON SPIN RESONANCE; ELECTRONS; FLUORINE COMPOUNDS; HOLES; PHOSPHATE GLASS; RADIATION DOSES; RADIATION MONITORING; RADIOTHERAPY; SAMARIUM; SAMARIUM IONS; X RADIATION; X-RAY DOSIMETRY