Calibration of the Al2O3:C optically stimulated luminescence (OSL) signal for linear energy transfer (LET) measurements in therapeutic proton beams
Calibration of the Al2O3:C optically stimulated luminescence (OSL) signal for linear energy transfer (LET) measurements in therapeutic proton beams
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DOI：
10.1088/0031-9155/59/15/4295
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发表时间：
2014-08-07
影响因子：
3.5
通讯作者：
Sawakuchi, Gabriel O.
中科院分区：
文献类型：
--
作者：
Granville, Dal A.;Sahoo, Narayan;Sawakuchi, Gabriel O.
光释光探测器（OSLDs）在质子治疗束的线性能量传递（LET）测量中显示出了潜力。然而，该技术缺乏临床实施所需的效率，并且期望更快、更简单的LET测量方法。这项工作的目的是证明和评估的潜力，校准Al 2 O3：C OSLD LET测量使用新的方法。我们将一批OSLD暴露于不同LET的未调制质子束中，并校准了所得到的OSL信号的三个参数作为通量平均LET（φ-LET）和剂量平均LET（D-LET）的函数。这三个参数包括在连续波刺激（CW-OSL）下评价的OSL曲线形状、在脉冲刺激（P-OSL）下评价的OSL曲线形状以及Al 2 O3：C OSL发射光谱中两个主要发射带的强度比（紫外[UV]/蓝色比）。为了测试校准，我们然后在不同LET的调制质子束中照射新批次的OSL LD，并使用OSL信号参数来计算这些新测试条件下的phi-LET和D-LET。使用P-OSL曲线形状，测量的D-LET在预期值的5.7%范围内。我们的结论是，从一个单一的10秒读出（初始校准后），质子治疗束的吸收剂量和LET可以使用OSLD测量。这在质子疗法治疗计划的质量保证中具有潜在的未来应用，特别是对于那些可能在其优化中考虑LET或相对生物有效性的治疗计划。在这项工作中证明的方法也可以适用于其他粒子治疗束，包括碳离子束。
Optically stimulated luminescence (OSL) detectors (OSLDs) have shown potential for measurements of linear energy transfer (LET) in proton therapy beams. However, the technique lacks the efficiency needed for clinical implementation, and a faster, simpler approach to LET measurements is desirable. The goal of this work was to demonstrate and evaluate the potential of calibrating Al2O3:C OSLDs for LET measurements using new methods. We exposed batches of OSLDs to unmodulated proton beams of varying LET and calibrated three parameters of the resulting OSL signals as functions of fluence-averaged LET (phi-LET) and dose-averaged LET (D-LET). These three parameters included the OSL curve shape evaluated under continuous wave stimulation (CW-OSL), the OSL curve shape evaluated under pulsed stimulation (P-OSL), and the intensity ratio of the two main emission bands in the Al2O3:C OSL emission spectrum (ultraviolet [UV]/blue ratio). To test the calibration, we then irradiated new batches of OSLDs in modulated proton beams of varying LET, and used the OSL signal parameters to calculate phi-LET and D-LET under these new test conditions. Using the P-OSL curve shape, D-LET was measured within 5.7% of the expected value. We conclude that from a single 10 s readout (following initial calibration), both the absorbed dose and LET in proton therapy beams can be measured using OSLDs. This has potential future applications in the quality assurance of proton therapy treatment plans, particularly for those that may account for LET or relative biological effectiveness in their optimization. The methods demonstrated in this work may also be applicable to other particle therapy beams, including carbon ion beams.