Radiation Research Division, Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde, Denmark.
Phys Med Biol. 2011 May 21;56(10):3033-45. doi: 10.1088/0031-9155/56/10/009. Epub 2011 Apr 20.
A fast-readout dosimetry system based on fibre-coupled organic scintillators has been developed for the purpose of conducting point measurements of absorbed dose in radiotherapy beams involving high spatial and temporal dose gradients. The system measures the dose for each linac radiation pulse with millimetre spatial resolution. To demonstrate the applicability of the system in complex radiotherapy fields, output factors and per cent depth dose measurements were performed in solid water for a 6 MV photon beam and compared with Monte Carlo simulated doses for square fields down to 0.6 cm × 0.6 cm size. No significant differences between measurements and simulations were observed. The temporal resolution of the system was demonstrated by measuring dose per pulse, beam start-up transients and the quality factor for 6 MV. The precision of dose per pulse measurements was within 2.7% (1 SD) for a 10 cm × 10 cm field at 10 cm depth. The dose per pulse behaviour compared well with linac target current measurements and accumulated dose measurements, and the system was able to resolve transient dose delivery differences between two Varian linac builds. The system therefore shows promise for reference dosimetry and quality assurance of complex radiotherapy treatments.
已经开发出一种基于光纤耦合有机闪烁体的快速读出剂量测量系统，用于对涉及高空间和时间剂量梯度的放射治疗束中的吸收剂量进行点测量。该系统以毫米空间分辨率测量每个直线加速器辐射脉冲的剂量。为了证明该系统在复杂放射治疗场中的适用性，在固体水中对 6 MV 光子束进行了输出因子和百分深度剂量测量，并与 0.6 cm×0.6 cm 尺寸的方形射野的蒙特卡罗模拟剂量进行了比较。测量值与模拟值之间没有观察到显著差异。通过测量每个脉冲的剂量、束启动瞬变和 6 MV 的品质因数，证明了系统的时间分辨率。在 10 cm 深度的 10 cm×10 cm 射野中，每个脉冲的剂量测量精度在 2.7%（1 标准差）以内。每个脉冲的剂量行为与直线加速器靶电流测量和累积剂量测量吻合良好，并且该系统能够分辨两个瓦里安直线加速器结构之间的瞬态剂量传递差异。因此，该系统有望用于复杂放射治疗的参考剂量测量和质量保证。
