Dual-storage phosphor proton therapy dosimetry: Simultaneous quantification of dose and linear energy transfer.
Dual-storage phosphor proton therapy dosimetry: Simultaneous quantification of dose and linear energy transfer.
复制标题
DOI：
10.1002/mp.14748
复制
发表时间：
2021-04
期刊：
影响因子：
3.8
通讯作者：
Li HH
中科院分区：
文献类型：
--
作者：
Setianegara J;Mazur TR;Yang D;Li HH
为了研究使用高Zeff存储磷光体材料BaFBrI：Eu 2+结合低Zeff存储磷光体材料KCl：Eu 2+用于同时质子剂量和线性能量传递（LET）测量的可行性，通过1）测量BaFBrI：Eu 2+的基本光学和剂量学性质，2）评估其与KCl：Eu 2+剂量计同时读出的兼容性，以及3）建模并验证其在升高的质子LET照射下的LET依赖性。商业BaFBrI：Eu 2+存储磷光体检测器（型号ST-VI，Fujifilm）用能量色散X射线分析（EDS）表征以获得其元素组成。使用Mevion S250质子治疗单元（位于扩展布拉格峰（SOBP）的中心）和Varian Clinac iX直线加速器（后者为低LET辐照）对剂量计进行辐照。测量了探测器在质子和光子辐照后的光激励发光（PSL）发射光谱、激发光谱和发光寿命。利用实验室光学读出器研究了质子辐照后的剂量学特性，包括剂量线性、剂量率依赖性、辐射硬度、时间稳定性和读出稳定性。此外，它的质子能量依赖性进行了分析建模和实验验证，通过照射探测器在SOBP内的各种深度（范围：15.0 g/cm 2，调制：10.0 g/cm 2）。发现用于高Zeff存储磷光体检测器的活性检测器组合物为BaFBr 0.85I0.15：Eu 2+。BaFBr_（0.85）I_（0.15）：Eu ~（2+）材料在质子和光子辐照下的激发和发射光谱一致，峰值分别为586 ± 1 nm和400 ± 1 nm，半高宽分别为119 ± 3 nm和30 ± 2 nm。由于一般认为光子辐照下的剂量计响应不受LET效应的影响，这些结果表明LET与电离辐射引起的电荷储存中心类型无关。与KCl：Eu 2+剂量计有足够的光谱重叠，允许两个剂量计在等效读出条件下读出，即594 nm刺激和420 nm检测波长。其PSL特征寿命被发现小于5微秒，这将使其适合于快速2D读出后照射。其420 nm的发射带强度被发现是线性高达10戈伊的绝对质子剂量在相同的辐照条件下，剂量率无关，稳定的时间和多次读出，并具有高辐射硬度下累积质子剂量历史高达200戈伊的测试在这项研究中。BaFBr0.85I0.15：Eu 2+在高LET区域表现出显著的质子能量依赖剂量响应不足，这可以通过阻止功率比计算来建模，在低LET区域的准确度为3%，在高LET区域（>5 keV/μm）的一致性距离（DTA）为1 mm。我们已经证明了双存储磷光体质子剂量学同时质子剂量和LET测量的可行性。BaFBr 0.85I0.15：Eu 2+显示出与其低Zeff互补KCl：Eu 2+同样优异的剂量测定性能，仅由于其较高的Zeff而具有独特的LET依赖性。这些有前途的结果铺平了道路，未来的研究涉及同时质子剂量和LET测量使用这种新的方法。
To investigate the feasibility of using the high Zeff storage phosphor material BaFBrI:Eu2+ in conjunction with the low Zeff storage phosphor material KCl:Eu2+ for simultaneous proton dose and linear energy transfer (LET) measurements by 1) measuring the fundamental optical and dosimetric properties of BaFBrI:Eu2+, 2) evaluating its compatibility in being readout simultaneously with KCl:Eu2+ dosimeters and 3) modeling and validating its LET dependence under elevated proton LET irradiation. A commercial BaFBrI:Eu2+ storage phosphor detector (Model ST-VI, Fujifilm) was characterized with energy dispersive x-ray analysis (EDS) to obtain its elemental composition. The dosimeters were irradiated using both a Mevion S250 proton therapy unit (at the center of a spread-out Bragg peak, SOBP) and a Varian Clinac iX linear accelerator with the latter being a low LET irradiation. The photostimulated luminescence (PSL) emission spectra, excitation spectra and luminescent lifetimes of the detector were measured post proton and photon irradiations. Dosimetric properties including dose linearity, dose rate dependence, radiation hardness, temporal and readout stabilities were studied using a laboratory optical reader after proton irradiations. In addition, its proton energy dependence was analytically modeled and experimentally validated by irradiating the detectors at various depths within the SOBP (Range: 15.0 g/cm2, Modulation: 10.0 g/cm2). The active detector composition for the high Zeff storage phosphor detector was found to be BaFBr0.85I0.15:Eu2+. The BaFBr0.85I0.15:Eu2+ material’s excitation and emission spectra were in agreement under proton and photon irradiations, with peaks of 586 ± 1 nm and 400 ± 1 nm respectively with a full-width-at-half-maximum (FWHM) of 119 ± 3 nm and 30 ± 2 nm respectively. As dosimeter response under photon irradiation is generally believed to be free from LET effect, these results suggest LET independence of charge storage center types resulted from ionizing radiations. There is sufficient spectral overlaps with KCl:Eu2+ dosimeters allowing both dosimeters to be readout under equivalent readout conditions, i.e. 594 nm stimulation and 420 nm detection wavelengths. Its PSL characteristic lifetime was found to be less than 5 microseconds which would make it suitable for fast 2D readout post irradiation. Its 420 nm emission band intensity was found to be linear up to 10 Gy absolute proton dose under the same irradiation conditions, dose rate independent, stable in time and under multiple readouts, and with high radiation hardness under cumulative proton dose histories up to 200 Gy as tested in this study. BaFBr0.85I0.15:Eu2+ showed significant proton energy- dependent dose under-response in regions of high LET which could be modeled by stopping power ratio calculations with an accuracy of 3% in low LET regions and a distance-to-agreement (DTA) of 1 mm in high LET regions (>5 keV/μm). We have proven the feasibility of dual-storage phosphor proton dosimetry for simultaneous proton dose and LET measurements. BaFBr0.85I0.15:Eu2+ has shown equally excellent dosimetry performance as its low Zeff complement KCl:Eu2+ with distinctive LET dependence merely as a result of its higher Zeff. These promising results pave the way for future studies involving simultaneous proton dose and LET measurements using this novel approach.
登录
查看更多内容
影响因子：
3.5
作者：
Granville, Dal A.;Sahoo, Narayan;Sawakuchi, Gabriel O.
通讯作者：
Sawakuchi, Gabriel O.
影响因子：
2
作者：
Kase, Yuki;Yamashita, Haruo;Murayama, Shigeyuki
通讯作者：
Murayama, Shigeyuki
影响因子：
3.8
作者：
Almond, PR;Biggs, PJ;Rogers, DWO
通讯作者：
Rogers, DWO
DOI：
10.1016/j.ijrobp.2015.09.018
发表时间：
2016-05-01
影响因子：
7
作者：
Bradley, Julie A.;Dagan, Roi;Mendenhall, Nancy P.
通讯作者：
Mendenhall, Nancy P.
影响因子：
3.8
作者：
Arjomandy, Bijan;Taylor, Paige;Kase, Yuki
通讯作者：
Kase, Yuki