Jursinic Paul A
West Michigan Cancer Center, 200 North Park Street, Kalamazoo, MI, 49007, USA.
Med Phys. 2020 Jul;47(7):3191-3203. doi: 10.1002/mp.14182. Epub 2020 May 14.
To investigate the dose response of optically stimulated luminescent dosimeters (OSLDs), and how this response changes with repeated use, increased accumulated dose, and bleaching light with or without a UV component. To devise a method to stabilize dose response characteristics of OSLDs that are used repeatedly. To decrease measurement uncertainty.
Optically stimulated luminescent dosimeters irradiations were made using a linear accelerator and Ir-192. The OSLDs (InLight nanoDots) dose response was characterized for these various irradiations under the batch, single use, method and the repeated irradiation method. Some nanoDots were preirradiated with hundreds of Gray of dose with Ir-192 gamma rays. Repeated use OSLDs were bleached with lights that had different UV content. A special bleaching light was fabricated and used that had the same spectrum as the light in the OSLD reader.
New, never irradiated, nanoDots had their characteristics altered by illumination with bleaching light that had a UV component. Each new nanoDot had unique sensitivity to dose as well as a unique linearity factor, which was supra-linear. NanoDots that were irradiated and bleached repeatedly had changes in low and high dose sensitivity that was altered if the bleaching light had UV in its spectrum. For nanoDots that have been preirradiated with up to 1500 Gy of dose, their dose response was supra-linear for bleaching light without UV content and infra-linear for light with UV content. Preirradiated nanoDots that were bleached with light without UV content had stable dose sensitivity (±1.5%), stable linearity factor (±3.5%) for over 10 bleaching cycles, nonlinear response that was quadratic in dose, and dose measurement uncertainty of ±1.4% for 277 measurements.
The UV component in bleaching light has an impact on the dose sensitivity characteristics shown by new or repeatedly irradiated nanoDots. Each new nanoDot has a unique sensitivity to dose as well as a unique linearity factor, which was supra-linear. As nanoDots accumulate dose with repeated use they change sensitivity to low and high dose very differently based on the UV content of the bleaching light. For nanoDots that have been preirradiated with hundreds of Gray of dose their dose response was supra-linear for bleaching light without UV content and infra-linear for light that has UV content. NanoDots can be used repeatedly and have stable dose response characteristics if they are preirradiated and bleached with light without UV content. Dose can be measured with an uncertainty of 1.4%, which is a threefold reduction of the uncertainty found with the single use batch method recommended by the manufacturer.
研究光激发发光剂量计（OSLD）的剂量响应，以及这种响应如何随重复使用、累积剂量增加以及含或不含紫外线成分的漂白光而变化。设计一种方法来稳定重复使用的OSLD的剂量响应特性。降低测量不确定度。
使用直线加速器和铱 - 192对光激发发光剂量计进行辐照。在批量、单次使用方法和重复辐照方法下，对这些不同辐照的OSLD（InLight纳米点）剂量响应进行表征。一些纳米点先用铱 - 192伽马射线预辐照数百戈瑞的剂量。用具有不同紫外线含量的光对重复使用的OSLD进行漂白。制作并使用了一种特殊的漂白光，其光谱与OSLD阅读器中的光相同。
新的、从未辐照过的纳米点，其特性会因含紫外线成分的漂白光照射而改变。每个新纳米点对剂量具有独特的灵敏度以及独特的线性因子，该线性因子是超线性的。经过反复辐照和漂白的纳米点，其低剂量和高剂量灵敏度会发生变化，如果漂白光光谱中含有紫外线，这种变化会有所不同。对于已预辐照高达1500戈瑞剂量的纳米点，其对不含紫外线成分的漂白光的剂量响应是超线性的，而对含紫外线成分的光的剂量响应是次线性的。用不含紫外线成分的光漂白的预辐照纳米点，在超过10次漂白循环中具有稳定的剂量灵敏度（±1.5%）、稳定的线性因子（±3.5%）、剂量的非线性二次响应以及277次测量中±1.4%的剂量测量不确定度。
漂白光中的紫外线成分会影响新的或反复辐照的纳米点所表现出的剂量灵敏度特性。每个新纳米点对剂量具有独特的灵敏度以及独特的线性因子，该线性因子是超线性的。随着纳米点因重复使用而累积剂量，它们对低剂量和高剂量的灵敏度变化因漂白光的紫外线含量而有很大差异。对于已预辐照数百戈瑞剂量的纳米点，其对不含紫外线成分的漂白光的剂量响应是超线性的，而对含紫外线成分的光的剂量响应是次线性的。如果纳米点经过预辐照并用不含紫外线成分的光漂白，它们可以重复使用并具有稳定的剂量响应特性。剂量测量的不确定度为1.4%，这比制造商推荐的单次使用批量方法所发现的不确定度降低了三倍。
