Establishing the suitability of quantitative optical CT microscopy of PRESAGE® radiochromic dosimeters for the verification of synchrotron microbeam therapy

作者: Simon J Doran , AT Abdul Rahman , Elke Bräuer-Krisch , Thierry Brochard , John Adamovics

DOI: 10.1088/0031-9155/58/18/6279

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摘要: Previous research on optical computed tomography (CT) microscopy in the context of synchrotron microbeam has shown potential technique and demonstrated high quality images, but left two questions unanswered: (i) are images suitably quantitative for 3D dosimetry? (ii) what is impact spatial resolution system limited depth-of-field microscope optics? Cuvette imaging studies reported here that address these issues. Two sets cuvettes containing radiochromic plastic PRESAGE® were irradiated at ID17 biomedical beamline European Synchrotron Radiation facility over ranges 0-20 0-35 Gy a third set was range using standard medical linac. In parallel, three cylindrical PRESAGE® samples diameter 9.7 mm were with test patterns allowed capabilities CT to be verified, independent measurements modulation transfer function (MTF) made via different methods. Both spectrophotometric analysis gave linear dose response, gradients ranging from 0.036-0.041 cm(-1) Gy(-1) in 0.037 (optical units) Gy(-1) for imaging. High-quality, results obtained throughout volume, as illustrated by depth-dose profiles. These profiles monoexponential, attention coefficient PRESAGE® for synchrotron-generated x-ray beam measured (0.185 ± 0.02) cm(-1) in excellent agreement expectations. Low-level (<5%) residual image artefacts discussed detail. It possible resolve easily slit width 37 µm (which smaller than many microbeams used ID-17), some uncertainty remains whether low values MTF higher frequencies scanner related or result genuine (but non-ideal) distributions. We conclude our do indeed have intensities proportional density can thus basis accurate dosimetry. However, further investigations necessary before make measures peak-to-valley ratios small-diameter microbeams. suggest various strategies moving forward optimistic about future this system.

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