Department of Radiology, Duke University Medical Center, Box 3808, Erwin Rd, Durham, NC 27710, USA.
AJR Am J Roentgenol. 2012 Mar;198(3):621-7. doi: 10.2214/AJR.11.6831.
The purpose of this study was to assess the effect of peak kilovoltage on radiation dose and image quality in adult neck MDCT.
An anthropomorphic phantom with metal oxide semiconductor field effect transistor detectors was imaged with a 64-MDCT scanner. The reference CT protocol called for 120 kVp, and images obtained with that protocol were compared with CT images obtained with protocols entailing 80, 100, and 140 kVp. All imaging was performed with automatic tube current modulation. Organ dose and effective dose were determined for each protocol and compared with those obtained with the 120-kVp protocol. Image noise was evaluated objectively and subjectively for each protocol.
The highest organ doses for all protocols were to the thyroid, ocular lens, skin, and mandible. The greatest reductions in organ dose were for the bone marrow of the cervical spine and mandible: 43% and 35% with the 100-kVp protocol and 63% and 53% with the 80-kVp protocol. Effective dose decreased as much as 9% with the 100-kVp protocol and 12% with the 80-kVp protocol. Use of the 140-kVp protocol was associated with an increase in organ dose as high as 64% for bone marrow in the cervical spine and a 19% increase in effective dose. Image noise increased with lower peak kilovoltage. The measured noise difference was greatest at 80 kVp, absolute increases were less than 2.5 HU. There was no difference in subjective image quality among protocols.
Reducing the voltage from 120 to 80 kVp for neck CT can result in greater than 50% reduction in the absorbed organ dose to the bone marrow of the cervical spine and mandible without impairment in subjective image quality.
本研究旨在评估峰值千伏对成人颈部 MDCT 辐射剂量和图像质量的影响。
采用带有金属氧化物半导体场效应晶体管探测器的人体模型进行 64 层 MDCT 扫描。参考 CT 方案要求 120 kVp，比较了该方案与 80、100 和 140 kVp 方案的 CT 图像。所有成像均采用自动管电流调制。确定了每个方案的器官剂量和有效剂量，并与 120 kVp 方案的结果进行了比较。对每个方案的图像噪声进行了客观和主观评价。
所有方案中最高的器官剂量为甲状腺、晶状体、皮肤和下颌骨。骨髓剂量的降低最大：颈椎和下颌骨的骨髓剂量分别降低了 43%和 35%（100 kVp 方案）和 63%和 53%（80 kVp 方案）。有效剂量降低了 9%（100 kVp 方案）和 12%（80 kVp 方案）。使用 140 kVp 方案会导致颈椎骨髓的器官剂量增加高达 64%，有效剂量增加 19%。图像噪声随峰值千伏的降低而增加。在 80 kVp 时测量到的噪声差异最大，绝对值增加小于 2.5 HU。各方案的主观图像质量无差异。
将颈部 CT 的电压从 120 降低至 80 kVp 可使颈椎和下颌骨骨髓的吸收器官剂量降低 50%以上，而不影响主观图像质量。
