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Evaluation of calibration factor of OSLD toward eye lens exposure dose measurement of medical staff during IVR
Journal of Applied Clinical Medical Physics ( IF 2.0 ) Pub Date : 2020-10-14 , DOI: 10.1002/acm2.13042
Takashi Asahara 1, 2 , Hiroaki Hayashi 3 , Sota Goto 1 , Natsumi Kimoto 1 , Kazuki Takegami 1 , Tatsuya Maeda 1 , Yuki Kanazawa 4 , Tohru Okazaki 5 , Takuya Hashizume 5
Affiliation  

The eye lens is a sensitive organ of which an x‐ray exposure dose should be managed during interventional radiology (IVR). In the actual situations, the eye lens is exposed to scattered x‐rays; they have different from the standard x‐ray energies which are used for general dose calibration of the dosimeter. To perform precise dose measurement, the energy dependence of the dosimeter should be properly accounted for when calibrating the dosimeter. The vendor supplies a calibration factor using 80‐kV diagnostic x‐rays under a free‐air condition. However, whether it is possible to use this calibration factor to evaluate the air kerma during the evaluation of the eye lens dose is unclear. In this paper, we aim to precisely determine calibration factors, and also examine the possible application of using a vendor‐supplied calibration factor. First, the x‐ray spectrum at the eye lens position during fluoroscopy was measured with a CdTe x‐ray spectrometer. We mimicked transfemoral cardiac catheterization using a human‐type phantom. Second, we evaluated the doses and calibration factors at three dosimetric points: front and back of protective goggles, and the front of the head (eye lens position). We used the measured x‐ray spectrum to determine the incident photon distribution in the eye lens regions, and x‐ray spectra corresponding to the dosimetric points around the eye lens were estimated using Monte Carlo simulation. Although the calibration factors varied with dosimetric positions, we found that the factors obtained were similar to the vendor‐supplied calibration factor. Furthermore, based on the experiment, we propose a practical way to calibrate an OSL dosimeter in an actual clinical situation. A person evaluating doses can use a vendor‐supplied calibration factor without any corrections for energy dependences, only when they add a systematic uncertainty of 5%. This evidence will strongly support actual exposure dose measurement during a clinical study.

中文翻译:

IVR期间医务人员眼镜暴露剂量测量的OSLD校准因子评估

眼透镜是一个敏感器官,在介入放射学(IVR)期间应控制其X射线暴露剂量。在实际情况下,眼镜片会暴露在散射的X射线下。它们与剂量计一般剂量校准所使用的标准X射线能量不同。为了进行精确的剂量测量,在校准剂量计时应适当考虑剂量计的能量依赖性。供应商在自由空气条件下使用80kV诊断X射线提供校准因子。但是,尚不清楚在评估晶状体剂量期间是否可以使用该校准系数来评估空气比释动能。在本文中,我们旨在精确确定校准因子,并研究使用供应商提供的校准因子的可能应用。第一,用CdTe X射线光谱仪测量荧光镜检查期间在眼睛晶状体位置的X射线光谱。我们使用人类模型来模拟经股动脉心脏导管插入术。其次,我们评估了三个剂量点的剂量和校准系数:防护眼镜的正面和背面,以及头部的正面(眼镜的位置)。我们使用测得的X射线光谱确定入射光在晶状体区域的分布,并使用Monte Carlo模拟估算与晶状体周围的剂量点相对应的X射线光谱。尽管校准因子随剂量位置而变化,但我们发现获得的因子与供应商提供的校准因子相似。此外,根据实验,我们提出了一种在实际临床情况下校准OSL剂量计的实用方法。评估剂量的人员只有在添加了系统不确定性5%的情况下,才可以使用供应商提供的校准因子,而无需对能量依赖性进行任何校正。该证据将有力地支持临床研究期间实际暴露剂量的测量。
更新日期:2020-12-01
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