Department of Medical Physics, Jack Ady Cancer Centre, Lethbridge, Alberta, Canada. Department of Oncology, University of Calgary, Calgary, Alberta, Canada. Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada. Author to whom any correspondence should be addressed.
Phys Med Biol. 2020 Jul 31;65(15):155019. doi: 10.1088/1361-6560/ab9e55.
The novel coronavirus, SARS-CoV-2, that causes the COVID-19 disease currently has healthcare systems around the world dealing with unprecedented numbers of critically ill patients. One of the primary concerns associated with this illness is acute respiratory distress syndrome (ARDS) and the pneumonia that accompanies it. Historical literature dating back to the 1940s and earlier contains many reports of successful treatment of pneumonias with ionizing radiation. Although these were not randomized controlled trials, they do suggest a potential avenue for further investigation. Technical details in these reports however were limited. In this work we review the literature and identify details including nominal kilovoltage ranges, filtration, and focus-skin distances (FSDs). Using a freely available and benchmarked code, we generated spectra and used these as sources for Monte Carlo simulations using the EGSnrc software package. The approximate sources were projected through a radiologically anthropomorphic phantom to provide detailed dose distributions within a targeted lung volume (approximate right middle lobe). After accounting for the reported exposure levels, mean lung doses fell in a relatively narrow range: 30-80 cGy. Variation in patient dimensions and other details are expected to result in an uncertainty on the order of ± 20%. This result is consistent with the dose range expected to induce anti-inflammatory effects.
新型冠状病毒（SARS-CoV-2）引发的 COVID-19 疾病目前使全球的医疗体系面临着前所未有的大量重症患者。该疾病的主要关注点之一是急性呼吸窘迫综合征（ARDS）和随之而来的肺炎。可追溯到 20 世纪 40 年代及更早时期的历史文献中包含许多关于使用电离辐射成功治疗肺炎的报告。尽管这些并非随机对照试验，但它们确实提示了进一步研究的潜在途径。然而，这些报告中的技术细节非常有限。在这项工作中，我们回顾了文献，并确定了包括标称千伏范围、过滤和焦点-皮肤距离（FSD）在内的详细信息。我们使用免费提供且经过基准测试的代码生成了光谱，并使用这些光谱作为 EGSnrc 软件包中的蒙特卡罗模拟的源。近似源通过放射学人体模型进行投影，以提供靶向肺体积（近似右中叶）内的详细剂量分布。在考虑了报告的暴露水平后，平均肺剂量落在相对较窄的范围内：30-80 cGy。患者尺寸和其他细节的变化预计会导致约±20%的不确定性。这一结果与预期诱导抗炎作用的剂量范围一致。
