Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215, USA.
AJR Am J Roentgenol. 2011 Oct;197(4):929-34. doi: 10.2214/AJR.10.6401.
We compared phantom organ doses delivered to breast, lung, and pelvis by five protocols using current dose reduction methods for routine chest CT and pulmonary CT angiography.
We measured the radiation dose to an anthropomorphic phantom using 64-MDCT with metal oxide semiconductor field effect transistor (MOSFET) detectors in the breast (skin and parenchyma), the lungs, and the pelvis (upper and lower). We compared the following five protocols: protocol 1, 120 kVp, automatic dose modulation, 120-320 mA; protocol 2, 120 kVp, automatic dose modulation, 60-200 mA; protocol 3, 100 kVp and fixed dose of 200 mA; protocol 4, 120 kVp, automatic dose modulation, 200-394 mA; and protocol 5, 80 kVp and fixed dose of 120 mA. Organ doses in milligrays and as a percentage of the volume CT dose index (CTDI(vol)) were compared using the analysis of variance for repeated measurements.
Protocol 1 delivered the highest breast dose (mean ± SD, 15.8 ± 1.8 mGy; 110.5% of CTDI(vol)). A decrease in breast radiation of more than 50% was achieved with protocol 3 (4.8 ± 1.8 mGy; 91.7% of CTDI(vol)) compared with protocol 4 (13.1 ± 5.5 mGy; 87.0% of CTDI(vol)) (p = 0.003). The lung received the highest organ dose regardless of the protocol (protocol 4: 21.5 ± 1.7 mGy; 142.5% of CTDI(vol)). Pelvic radiation was low regardless of protocol and did not exceed 0.2 mGy (up to 3.7% of CTDI(vol); p = 0.118-0.999).
The results of this anthropomorphic phantom study showed substantial and significant variation in radiation doses to the breast and lungs depending on the scanning protocol used with the potential for over threefold dose reduction.
我们比较了五种使用当前胸部 CT 和肺动脉 CT 血管造影剂量降低方法的方案，以评估其对乳腺、肺和骨盆的器官剂量的影响。
我们使用配备金属氧化物半导体场效应晶体管 (MOSFET) 探测器的 64 排 MDCT 对一个人体模型进行了辐射剂量测量，包括乳腺（皮肤和实质）、肺部和骨盆（上、下部）。我们比较了以下五种方案：方案 1，120kVp，自动剂量调节，120-320mA；方案 2，120kVp，自动剂量调节，60-200mA；方案 3，100kVp 及固定剂量 200mA；方案 4，120kVp，自动剂量调节，200-394mA；方案 5，80kVp 及固定剂量 120mA。我们使用重复测量方差分析比较了毫戈瑞（mGy）和作为体剂量指数（CTDI(vol)）百分比的器官剂量。
方案 1 提供了最高的乳腺剂量（平均值 ± 标准差，15.8 ± 1.8mGy；110.5%的 CTDI(vol)）。与方案 4（13.1 ± 5.5mGy；87.0%的 CTDI(vol)）相比，方案 3（4.8 ± 1.8mGy；91.7%的 CTDI(vol)）可使乳腺辐射降低超过 50%（p=0.003）。无论方案如何，肺部都会接收到最高的器官剂量（方案 4：21.5 ± 1.7mGy；142.5%的 CTDI(vol)）。骨盆辐射无论方案如何都很低，不超过 0.2mGy（最高达 3.7%的 CTDI(vol)；p=0.118-0.999）。
这项人体模型研究的结果表明，使用不同的扫描方案时，乳腺和肺部的辐射剂量存在显著差异，且有可能降低三倍以上。
