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Extending the Dynamic Range of Radiochromic Film. Oliver Ettlinger Ion Instrumentation Workshop, LULI 07-06-2012. Overview. Radiochromic film calibration Film overview Data extraction HD-810, HD-V2 and EBT-2 comparisons Extending the dynamic range of RCF
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Extending the Dynamic Range of Radiochromic Film Oliver Ettlinger Ion Instrumentation Workshop, LULI 07-06-2012
Overview • Radiochromic film calibration • Film overview • Data extraction • HD-810, HD-V2 and EBT-2 comparisons • Extending the dynamic range of RCF • Ultraviolet wavelengths and their benefits for HD-810 • Application to HD-V2 and EBT-2
Film Overview • HD-V2: • 10 – 1000Gy • Yellow marker dye • EBT-2: • 1cGy – 40Gy • Greater low energy sensitivity • HD-810: • 10 – 400Gy • Optical density proportional to dose and flux
Traditional Data Extraction • Calibration with known dose exposures – cyclotron • Flatbed scanner – RGB scans and independent channel analysis for improved range of dose data obtainable • 2D spatial intensity profiles and beam divergence obtained
Traditional Data Extraction 100Gy 1000Gy 10000Gy
HD-810 and HD-V2 • Red Channel – <200Gy • Blue Channel – doses above 1kGy • At least 150kGy dose limit in blue – much larger than previously obtained results* • Red Channel – <1000Gy • Green channel – 1000Gy – 10kGy • Blue channel - >10kGy • Better Dose Range – reduced sensitivity • *G. Scott et al. CLF Annual Report 2010-2011
HD-V2 and EBT-2 • Red channel – <1000Gy • Green channel – 1000Gy – 10kGy • Blue channel - >10kGy • Thicker active layer – increased sensitivity • Red/Green channel up to 100Gy • Blue Channel up to 1000Gy Novel stack designs
Extending the Dynamic Range • Blue turns over at ~30kGy • UV and IR do not exhibit multi-valued nature in range observed • Transmission of multiple wavelengths through HD-810 film* • Ultraviolet most suitable above 10kGy – gradient and range of transmission values • *G. Scott et al. CLF Annual Report 2010-2011
UV (365 nm) bandpass filter UV (365 nm) LED array RCF holder Andor 16-bit CMOS camera Glass scatter screen
Results Digitised using Nikon Flatbed Scanner UV Light Source Reaching up to ~ 200kGy in ‘rings’ using calibration on next slide RGB Channels
Dose Extraction in UV • Analogous to method for flatbed scanner • Calibration obtained using known doses Can this be extended to HD-V2 or EBT-2
Extending the Range of HD-V2 • Should be possible to use any of the three wavelength regimes up to 100kGy • Blue preferable due to gradient – transmission range could be an issue?
Extending the Range of EBT-2 • Desirable due to high sensitivity • No UV data due to negligible transmission at all doses • Both turn over at low doses – no obvious extension of the range
Conclusions • HD-V2 has similar characteristics to HD-810 but greater dynamic range • HD-V2 and EBT-2 should be used in conjunction for better data collection • UV wavelengths extend the dynamic range by at least an order of magnitude • Method already proven with real data analysis
Acknowledgements • James Green, Ceri Brenner, Graeme Scott and David Neely Central Laser Facility, STFC • David Parker, Stuart Green and Francesca Fiorini University of Birmingham