Department of Diagnostic and Interventional Imaging, UTHealth McGovern Medical School, Houston, Texas, United States of America.
Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
PLoS One. 2018 Nov 16;13(11):e0205803. doi: 10.1371/journal.pone.0205803. eCollection 2018.
Strong magnetic fields affect radiation dose deposition in MRI-guided radiation therapy systems, particularly at interfaces between tissues of differing densities such as those in the thorax. In this study, we evaluated the impact of a 1.5 T magnetic field on radiation-induced lung damage in C57L/J mice. We irradiated 140 mice to the whole thorax with parallel-opposed Co-60 beams to doses of 0, 9.0, 10.0, 10.5, 11.0, 12.0, or 13.0 Gy (20 mice per dose group). Ten mice per dose group were irradiated while a 1.5 T magnetic field was applied transverse to the radiation beam and ten mice were irradiated with the magnetic field set to 0 T. We compared survival and noninvasive assays of radiation-induced lung damage, namely respiratory rate and metrics derived from thoracic cone-beam CTs, between the two sets of mice. We report two main results. First, the presence of a transverse 1.5 T field during irradiation had no impact on survival of C57L/J mice. Second, there was a small but statistically significant effect on noninvasive assays of radiation-induced lung damage. These results provide critical safety data for the clinical introduction of MRI-guided radiation therapy systems.
强磁场会影响 MRI 引导放射治疗系统中的辐射剂量沉积，尤其是在组织密度不同的界面处，如胸部。在这项研究中，我们评估了 1.5 T 磁场对 C57L/J 小鼠辐射诱导性肺损伤的影响。我们用平行对置的 Co-60 射线对 140 只小鼠进行全胸照射，剂量分别为 0、9.0、10.0、10.5、11.0、12.0 或 13.0 Gy（每组 20 只）。每组 10 只小鼠在磁场横向施加于射束的情况下进行照射，每组 10 只小鼠在磁场设置为 0 T 的情况下进行照射。我们比较了两组小鼠的生存情况和辐射诱导性肺损伤的非侵入性检测，即呼吸频率和来自胸部锥形束 CT 的指标。我们报告了两个主要结果。首先，在照射过程中存在横向 1.5 T 场对 C57L/J 小鼠的生存没有影响。其次，对辐射诱导性肺损伤的非侵入性检测有微小但具有统计学意义的影响。这些结果为 MRI 引导放射治疗系统的临床引入提供了关键的安全数据。
