Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Phys Med Biol. 2010 Apr 21;55(8):2411-26. doi: 10.1088/0031-9155/55/8/018. Epub 2010 Apr 1.
This study computationally assessed the temperature elevations due to electromagnetic wave energy deposition during magnetic resonance imaging in non-pregnant and pregnant woman models. We used a thermal model with thermoregulatory response of the human body for our calculations. We also considered the effect of blood temperature variation on body core temperature. In a thermal equilibrium state, the temperature elevations in the intrinsic tissues of the woman and fetal tissues were 0.85 and 0.61 degrees C, respectively, at a whole-body averaged specific absorption rate of 2.0 W kg(-1), which is the restriction value of the International Electrotechnical Commission for the normal operating mode. As predicted, these values are below the temperature elevation of 1.5 degrees C that is expected to be teratogenic. However, these values exceeded the recommended temperature elevation limit of 0.5 degrees C by the International Commission on Non-Ionizing Radiation Protection. We also assessed the irradiation time required for a temperature elevation of 0.5 degrees C at the aforementioned specific absorption rate. As a result, the calculated irradiation time was 40 min.
本研究通过计算在非妊娠和妊娠女性模型中进行磁共振成像时由于电磁波能量沉积引起的温升。我们使用了一个具有人体体温调节反应的热模型进行计算。我们还考虑了血液温度变化对体核温度的影响。在热平衡状态下，全身平均比吸收率为 2.0 W/kg 时，女性固有组织和胎儿组织的温升分别为 0.85 和 0.61 摄氏度，这是国际电工委员会对正常工作模式的限制值。如预测的那样，这些值低于预计有致畸作用的 1.5 摄氏度温升。然而，这些值超过了国际非电离辐射防护委员会推荐的 0.5 摄氏度温升限值。我们还评估了在上述比吸收率下温升 0.5 摄氏度所需的辐照时间。结果，计算出的辐照时间为 40 分钟。
