Development of three-dimensional dose verification system using a fluorescent screen in ion beam therapy

For quality assurance (QA) of therapeutic ion beams, QA tool having high spatial resolution and quick verification is required. The imaging system with a fluorescent screen is suitable for QA procedure. We developed a quick verification system (NQA-SCN) using a fluorescent screen with a charge-coupled device (CCD) camera for the sake of two dimensional dosimetry. In carbon-ion therapy, the fluorescent light is decreased by suffering from quenching effect due to the increased linear energy transfer (LET) in the Bragg peak. For the use of three-dimensional dose verification, we performed a simple correction for quenching effect and several types of corrections for the optical artifact. In addition, NQA-SCN is attached with an accordion-type water phantom which makes it possible to easily change measurement depth. To evaluate the performance of NQA-SCN, we carried out experiments concerning QA procedures. In my presentation, we provide correction methods and detailed analysis of measured results.The 3rd International Beam Instrumentation Coference (IBIC2014