Department of Effects and Risks of Ionizing and Non-Ionizing Radiation, Federal Office for Radiation Protection (BfS), Oberschleißheim, Germany.
Department of Medical and Occupational Radiation Protection, Federal Office for Radiation Protection (BfS), Oberschleißheim, Germany.
Front Public Health. 2022 May 17;10:903509. doi: 10.3389/fpubh.2022.903509. eCollection 2022.
In biological dosimetry, dose-response curves are essential for reliable retrospective dose estimation of individual exposure in case of a radiation accident. Therefore, blood samples are irradiated and evaluated based on the applied assay. Accurate physical dosimetry of the irradiation performance is a critical part of the experimental procedure and is influenced by the experimental setup, especially when X-ray cabinets are used. The aim of this study was to investigate variations and pitfalls associated with the experimental setups used to establish calibration curves in biological dosimetry with X-ray cabinets. In this study, irradiation was performed with an X-ray source (195 kV, 10 mA, 0.5 mm Cu filter, dose rate 0.52 Gy/min, 1 and 2 half-value layer = 1.01 and 1.76 mm Cu, respectively, average energy 86.9 keV). Blood collection tubes were irradiated with a dose of 1 Gy in vertical or horizontal orientation in the center of the beam area with or without usage of an additional fan heater. To evaluate the influence of the setups, physical dose measurements using thermoluminescence dosimeters, electron paramagnetic resonance dosimetry and ionization chamber as well as biological effects, quantified by dicentric chromosomes and micronuclei, were compared. This study revealed that the orientation of the sample tubes (vertical vs. horizontal) had a significant effect on the radiation dose with a variation of -41% up to +49% and contributed to a dose gradient of up to 870 mGy inside the vertical tubes due to the size of the sample tubes and the associated differences in the distance to the focal point of the tube. The number of dicentric chromosomes and micronuclei differed by ~30% between both orientations. An additional fan heater had no consistent impact. Therefore, dosimetric monitoring of experimental irradiation setups is mandatory prior to the establishment of calibration curves in biological dosimetry. Careful consideration of the experimental setup in collaboration with physicists is required to ensure traceability and reproducibility of irradiation conditions, to correlate the radiation dose and the number of aberrations correctly and to avoid systematical bias influencing the dose estimation in the frame of biological dosimetry.
在生物剂量学中，剂量-反应曲线对于在辐射事故发生时可靠地进行个体暴露的回溯剂量估计至关重要。因此，对血液样本进行辐照，并根据应用的测定方法进行评估。辐照性能的准确物理剂量学是实验过程的关键部分，并且受到实验设置的影响，特别是在使用 X 射线机时。本研究的目的是调查在使用 X 射线机建立生物剂量学校准曲线的实验设置中存在的差异和陷阱。在本研究中，使用 X 射线源（195 kV、10 mA、0.5 毫米铜过滤器、剂量率 0.52 Gy/min、1 和 2 半价层分别为 1.01 和 1.76 毫米铜、平均能量 86.9 keV）进行辐照。将血液采集管以垂直或水平方向置于光束区域中心进行辐照，辐照剂量为 1 Gy，有或没有使用附加风扇加热器。为了评估设置的影响，使用热释光剂量计、电子顺磁共振剂量计和电离室进行物理剂量测量，并通过双着丝粒染色体和微核进行生物效应评估。本研究表明，样品管的方向（垂直与水平）对辐射剂量有显著影响，变化范围为-41%至+49%，并由于样品管的大小和与焦点的距离差异，导致垂直管内的剂量梯度高达 870 mGy。两种方向的双着丝粒染色体和微核数量差异约为 30%。附加的风扇加热器没有一致的影响。因此，在建立生物剂量学校准曲线之前，必须对实验辐照设置进行剂量学监测。在建立生物剂量学校准曲线之前，必须对实验辐照设置进行剂量学监测。必须与物理学家仔细考虑实验设置，以确保辐照条件的可追溯性和可重复性，正确关联辐射剂量和畸变数量，并避免影响生物剂量学中剂量估计的系统偏差。
