利用管电流自动调节技术降低常规头部CT的照射剂量

目的 探讨常规头部CT采用管电流自动调节技术(即TCM螺旋扫描模式)能否降低照射剂量和提高影像质量。方法 50例成人患者,分别接受常规头部CT的TCM螺旋和常规轴扫模式,常规轴扫参数:140 kV,170mA用于颅底部;120 kV,150 mA用于颅脑部,2s/周。TCM螺旋扫描参数:120 kV,280 mA(最大管电流阈值),0.8 s/周。扫描剂量直接取自设备剂量指示值(CTDI和DLP)。影像质量分别由两位专家采用双盲法,对头部CT的颅底、脑灰-白质层面以及全部影像逐层进行CT值、信噪比测量以及综合评估。结果 常规头部CT采用TCM螺旋扫描模式较轴扫模式可使患者有效降低管电流使用量(44±12)mA,扫描时间(4.8±0.8)s,照射剂量(38±0.9)%:CTDI:(32.10±9.0)mGy、(55.00±7.2)mGy;DLP(442.10±72)mGy·cm、(668.00±26)mGy·cm];经计算人体吸收剂量可降低(1.5±0.4)mSv,并可有效提高影像质量。结论 经两种不同扫描模式所得影像的CT值测量结果及其他影像质量参数的对照,应用TCM螺旋扫描模式的影像质量完全可与轴扫描模式相媲美,同时具有可减少扫描时间和照射剂量的优越性。

Reducing Radiation Dose During Routine Brain CT using Helical with Tube Current Modulation Mode

Objective To determine whether radiation dose can be reduced and image quality improved in routine head CT that were acquired with organ-based tube current modulation (TCM) technology. Methods In a prospective study 50 adults patients scheduled for head CT used in both the routine axial and helical with TCM modes. Scan parameter:TCM mode were 120 kVp, 280 mA(Max mA threshold value), scan time 0.8s/rol. the manual mode were 140 kVp, 170 mA for petrou bone, and 120 kVp, 150 mA for brain, scan time 2.0s/rol. Radiation dose were measured directly from the CT scan indicated(CTDI and DLP). The image quality at the level of the posterior fossa and grey-white matter contrast and overall image were assessed by two readers using CT value and signal-to-noise ratio(SNR) detected, Reading orders were randomized. Results Compared the routine axial scan mode,The TCM scan mode reduced tube current (44 ±12) mA, exposure time (4.8 ±0.8) s, radiation dose (38 ±0.9)%CTDI:(32.10 ±9.0) mGy,(55.00 ±7.2) mGy; DLP (442.10 ±72) mGy ·cm,(668.00 ±26) mGy·cm]; The effective radiation dose is reduced by (1.5 ±0.4) mSv, respectively. The image quality was effectively improved. Conclusion Routine head CT scan using helical with TCM scan mode has reduced the superiority of the scan time and radiation dose. The image quality can comparable to routine axial scan mode.