Russo S, Mirandola A, Molinelli S, Mastella E, Vai A, Magro G, Mairani A, Boi D, Donetti M, Ciocca M
Fondazione CNAO, Pavia, Italy.
Fondazione CNAO, Pavia, Italy.
Phys Med. 2017 Feb;34:48-54. doi: 10.1016/j.ejmp.2017.01.011. Epub 2017 Jan 22.
Pencil beam scanning technique used at CNAO requires beam characteristics to be carefully assessed and periodically checked to guarantee patient safety. This study aimed at characterizing the Lynx® detector (IBA Dosimetry) for commissioning and periodic quality assurance (QA) for proton and carbon ion beams, as compared to EBT3 films, currently used for QA checks.
The Lynx® is a 2-D high-resolution dosimetry system consisting of a scintillating screen coupled with a CCD camera, in a compact light-tight box. The scintillator was preliminarily characterized in terms of short-term stability, linearity with number of particles, image quality and response dependence on iris setting and beam current; Lynx® was then systematically tested against EBT3 films. The detector response dependence on radiation LET was also assessed.
Preliminary results have shown that Lynx is suitable to be used for commissioning and QA checks for proton and carbon ion scanning beams; the cross-check with EBT3 films showed a good agreement between the two detectors, for both single spot and scanned field measurements. The strong LET dependence of the scintillator due to quenching effect makes Lynx® suitable only for relative 2-D dosimetry measurements.
Lynx® appears as a promising tool for commissioning and periodic QA checks for both protons and carbon ion beams. This detector can be used as an alternative of EBT3 films, allowing real-time measurements and analysis, with a significant time sparing.
中国国家离子束应用中心（CNAO）所使用的笔形束扫描技术要求对束流特性进行仔细评估并定期检查，以确保患者安全。本研究旨在对Lynx®探测器（IBA剂量学公司）进行特性描述，用于质子和碳离子束的调试及定期质量保证（QA），并与目前用于QA检查的EBT3胶片进行比较。
Lynx®是一种二维高分辨率剂量测定系统，由一个闪烁屏与一台电荷耦合器件（CCD）相机组成，置于一个紧凑的不透光盒中。首先对闪烁体的短期稳定性、与粒子数的线性关系、图像质量以及对光圈设置和束流的响应依赖性进行了特性描述；然后将Lynx®与EBT3胶片进行了系统测试。还评估了探测器响应对辐射传能线密度（LET）的依赖性。
初步结果表明，Lynx适用于质子和碳离子扫描束的调试及QA检查；与EBT3胶片的交叉检查表明，对于单点和扫描野测量，两种探测器之间具有良好的一致性。由于猝灭效应，闪烁体对LET的强烈依赖性使得Lynx®仅适用于相对二维剂量测定测量。
Lynx®似乎是一种用于质子和碳离子束调试及定期QA检查的有前景的工具。该探测器可作为EBT3胶片的替代品，能够进行实时测量和分析，可显著节省时间。
