Research and Practical Clinical Center for Diagnostics and Telemedicine Technologies of the Moscow Health Care Department, Moscow, Russian Federation.
Radiation Protection of Patients Unit, International Atomic Energy Agency, Vienna, Austria.
Eur Radiol Exp. 2021 May 28;5(1):21. doi: 10.1186/s41747-021-00218-0.
On March 11, 2020, the World Health Organization declared the coronavirus disease 2019 (COVID-19) pandemic. The expert organisations recommend more cautious use of thoracic computed tomography (CT), opting for low-dose protocols. We aimed at determining a threshold value of automatic tube current modulation noise index below which there is a chance to miss an onset of ground-glass opacities (GGO) in COVID-19. A team of radiologists and medical physicists performed 25 phantom CT studies using different automatic tube current modulation settings (Exposure3D technology). We then conducted a retrospective evaluation of the chest CT images from 22 patients with COVID-19 and calculated the density difference between the GGO and unaffected tissue. Finally, the results were matched to the phantom study results to determine the minimum noise index threshold value. The minimum density difference at the onset of COVID-19 was 252 HU (p < 0.001). This was found to correspond to the Exposure 3D noise index of 36. We established the noise index threshold of 36 for the Canon scanner without iterative reconstructions, allowing for a decrease in the dose-length product by 80%. The proposed protocol needs to be validated in a prospective study.
2020 年 3 月 11 日，世界卫生组织宣布 2019 年冠状病毒病（COVID-19）大流行。专家组织建议更谨慎地使用胸部计算机断层扫描（CT），选择低剂量方案。我们旨在确定自动管电流调制噪声指数的阈值，低于该阈值，有可能错过 COVID-19 中磨玻璃影（GGO）的出现。一组放射科医生和医学物理学家使用不同的自动管电流调制设置（Exposure3D 技术）进行了 25 次体模 CT 研究。然后，我们对 22 例 COVID-19 患者的胸部 CT 图像进行了回顾性评估，并计算了 GGO 与正常组织之间的密度差异。最后，将结果与体模研究结果进行匹配，以确定最小噪声指数阈值。COVID-19 发病时的最小密度差为 252 HU（p < 0.001）。这与 Exposure 3D 的噪声指数 36 相对应。我们为没有迭代重建的佳能扫描仪建立了 36 的噪声指数阈值，使剂量长度乘积降低了 80%。需要在前瞻性研究中验证该方案。
