Radiobiology group, Department of Human Structure and Repair, Ghent University, Ghent, Belgium.
Cell Death Investigation and Therapy Laboratory, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
Int J Radiat Biol. 2024;100(2):236-247. doi: 10.1080/09553002.2023.2261525. Epub 2024 Jan 29.
In radiology, low X-ray energies (<140 keV) are used to obtain an optimal image while in radiotherapy, higher X-ray energies (MeV) are used to eradicate tumor tissue. In radiation research, both these X-ray energies being used to extrapolate research to clinical practice. However, the energy deposition of X-rays depends on their energy spectrum, which might lead to changes in biological response. Therefore, this study compared the DNA damage response (DDR) in peripheral blood lymphocytes (PBLs) exposed to X-rays with varying beam quality, mean photon energy (MPE) and dose rate. The DDR was evaluated in peripheral blood lymphocytes (PBLs) by the ɣ-H2AX foci assay, the cytokinesis-block micronucleus assay and an SYTOX-based cell death assay, combined with specific cell death inhibitors. Cell cultures were irradiated with a 220 kV X-ray research cabinet (SARRP, X-Strahl) or a 6 MV X-ray linear accelerator (Elekta Synergy). Three main physical parameters were investigated: beam quality (V), MPE (eV) and dose rate (Gy/min). Additional copper (Cu) filtration caused variation in the MPE (78 keV, 94 keV, 118 keV) at SARRP; dose rates were varied by adjusting tube current for 220 kV X-rays (0.33-3 Gy/min) or water-phantom depth in the 6 MV set-up (3-6 Gy/min). The induction of chromosomal damage and initial (30 min) DNA double-stranded breaks (DSBs) were significantly higher for 220 kV X-rays compared to 6 MV X-rays, while cell death induction was similar. Specific cell death inhibitors for apoptosis, necroptosis and ferroptosis were not capable of blocking cell death after irradiation using low or high-energy X-rays. Additional Cu filtration increased the MPE, which significantly decreased the amount of chromosomal damage and DSBs. Within the tested ranges no specific effects of dose rate variation were observed. The DDR in PBLs is influenced by the beam quality and MPE. This study reinforces the need for consideration and inclusion of all physical parameters in radiation-related studies.
在放射学中，使用低 X 射线能量（<140keV）获得最佳图像，而在放射治疗中，使用更高的 X 射线能量（MeV）来消灭肿瘤组织。在辐射研究中，这两种 X 射线能量都被用于推断研究结果至临床实践。然而，X 射线的能量沉积取决于其能谱，这可能导致生物反应发生变化。因此，本研究比较了外周血淋巴细胞（PBL）暴露于不同束质、平均光子能量（MPE）和剂量率的 X 射线后的 DNA 损伤反应（DDR）。通过γ-H2AX 焦点分析、胞质分裂阻断微核分析和基于 SYTOX 的细胞死亡分析，结合特定的细胞死亡抑制剂，评估外周血淋巴细胞（PBL）中的 DDR。细胞培养物用 220kV X 射线研究用柜（SARRP，X-Strahl）或 6MV X 射线线性加速器（Elekta Synergy）进行照射。研究了三个主要的物理参数：束质（V）、MPE（eV）和剂量率（Gy/min）。在 SARRP 中，通过添加铜（Cu）过滤导致 MPE（78keV、94keV、118keV）的变化；通过调整 220kV X 射线的管电流（0.33-3Gy/min）或 6MV 设置中的水模深度（3-6Gy/min）来改变剂量率。与 6MV X 射线相比，220kV X 射线诱导的染色体损伤和初始（30 分钟）DNA 双链断裂（DSB）明显更高，而细胞死亡诱导则相似。用于凋亡、坏死和铁死亡的特定细胞死亡抑制剂在使用低能或高能 X 射线照射后无法阻断细胞死亡。添加 Cu 过滤会增加 MPE，从而显著减少染色体损伤和 DSB 的数量。在所测试的范围内，没有观察到剂量率变化的特定影响。PBL 中的 DDR 受束质和 MPE 的影响。本研究强调了在辐射相关研究中需要考虑并包含所有物理参数。
