A wide dynamic range, high spatial resolution readout system for radiochromic dye films

This paper describes the evaluation of an inexpensive, commercially available 35 mm transparency slide scanner as a potential alternative scanning device for GafChromic (TM) HD-810 radiochromic dye film. Besides its low cost, the principal advantages of this type of scanner are high spatial resolution and high speed (a typical scan taking less than 1 min). With broad-band illumination the useful dose range using grey-scale imaging of GafChromic (TM) HD-810 is limited to about 50-800 Gy. By using the colour-scale imaging capability of the scanner we have been able to achieve a significant extension covering a similar range(15-2000 Gy) to that attainable using monochromatic illumination. The short-term reproducibility of the system is good, with a coefficient of variation of doses estimated from repeat scanning of uniformly exposed calibration films of less than 2%. Long-term stability is ensured by the scanning of a manufacturer-supplied test slide. The slide scanner system has been used in the determination of depth dose distributions from a model 'hot particle' source containing (RU)-R-106/Rh. GafChromic (TM) dye film stacks irradiated by the source were read out on both the slide scanner and a conventional Joyce Loebl MDM6 scanning stage microdensitometer. The overall agreement between the dose estimates provided by the two systems was within 10%.