Liuzzi Raffaele, Savino Federica, D'Avino Vittoria, Pugliese Mariagabriella, Cella Laura
Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.
Department of Physics, Federico II University, Naples, Italy.
PLoS One. 2015 Oct 1;10(10):e0139287. doi: 10.1371/journal.pone.0139287. eCollection 2015.
Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2-12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters.
LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0-10 Gy in step of 2 Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy.
The TLD-100 dose-response curves were obtained. In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05).
This study demonstrates that the TLD dose response, for doses ≤10 Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided.
本研究的目的是调查热释光剂量计（TLD）对术中电子放射治疗（IOERT）束流的响应。在IOERT治疗中，手术期间会使用高剂量率电子束（2 - 12 cGy/脉冲）单次给予大剂量辐射。为了验证和记录所给予的剂量，体内剂量测定是质量保证的必要程序。TLD具有许多优点，例如探测器尺寸小且组织等效性好，这使其作为体内剂量计在IOERT中颇具吸引力。
用不同能量的IOERT电子束（5、7和9 MeV）以及6 MV常规光子束对LiF:Mg,Ti剂量计（TLD - 100）进行辐照。对于每种能量，TLD在0 - 10 Gy剂量范围内以2 Gy步长进行辐照。进行回归分析以确定热释光信号随剂量和能量的响应变化。
获得了TLD - 100的剂量响应曲线。在0 - 10 Gy剂量范围内，常规光子束的校准曲线被确认为线性。在相同剂量区域，当使用高剂量率电子束时，二次模型比线性模型表现更好（F检验；p < 0.05）。
本研究表明，对于剂量≤10 Gy，TLD在高剂量率电子束中的剂量响应呈抛物线行为。如果进行适当校准，TLD - 100可作为IOERT患者剂量测定的有用探测器。
