Effect of tube current on diagnostic image quality in paediatric cerebral multidetector CT images
Effect of tube current on diagnostic image quality in paediatric cerebral multidetector CT images
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DOI：
10.1259/bjr/24404354
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发表时间：
2009-04-01
影响因子：
2.6
通讯作者：
Thilander-Klang, A.
中科院分区：
文献类型：
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作者：
Ledenius, K.;Gustavsson, M.;Thilander-Klang, A.
本研究的目的是探讨管电流对儿童大脑多层螺旋CT(MDCT)诊断图像质量的影响，以确定重现可接受的不同诊断图像质量所需的最小辐射剂量。从25例儿童患者的常规多层螺旋CT脑部检查中回顾性选取原始数字扫描数据(原始数据)。所有检查均在八层螺旋CT(LightSpeedUltra，GE Healthcare)上使用轴向扫描进行。年龄从新生儿到15岁不等。量子噪声被人为地添加到原始数据中，表示剂量减少相当于20 mA的步长。患者身份信息已删除。三位经验丰富的放射科医生盲目和随机地评估了从大脑的两个不同层面产生的图像，涉及结构的复制和整体图像质量。使用量表间一致性的非参数统计方法对最终数据进行评估。建立了与患者年龄有关的再现足够诊断质量的图像所需的管电流时间乘积(MAs)的最小值。建立了相应的CT剂量指数(CTDI(VOL)(mGy值))。总而言之，当CTDIvol值降至20mGy时(患者1-5岁)，可接受的低对比度结构的复制是可能的。对于可接受的高对比度结构的复制，CTDI(VOL)值降至10mGy值被认为是可能的(患者1-5岁)。对于6个月以下(15mGy)的患者，原始图像质量被发现不足以令人满意地再现低对比度结构。
The aim of this study was to investigate the effect of tube current on diagnostic image quality in paediatric cerebral multidetector CT (MDCT) images in order to identify the minimum radiation dose required to reproduce acceptable levels of different diagnostic image qualities. Original digital scanning data (raw data) were selected retrospectively from routine MDCT brain examinations of 25 paediatric patients. All examinations had been performed using axial scanning on an eight-slice MDCT (LightSpeed Ultra, GE Healthcare). Their ages ranged from newborn to 15 years. Quantum noise was added artificially to the raw data representing dose reductions equivalent to steps of 20 mA. Patient identification information was removed. Three experienced radiologists blindly and randomly assessed the resulting images from two different levels of the brain with regard to reproduction of structures and overall image quality. Final data were evaluated using the non-parametric statistical approach of inter-scale concordance. The minimum value of tube current-time product (mAs) required to reproduce an image of sufficient diagnostic quality was established in relation to the age of the patient. The corresponding CT dose index values by volume (CTDI(vol) (mGy)) were also established. In conclusion, acceptable reproduction of low-contrast structures was possible at CTDIvol values down to 20 mGy (patients 1-5 years old). For acceptable reproduction of high-contrast structures, CTDI(vol) values down to 10 mGy were considered possible (patients 1-5 years old). The original image quality for patients under 6 months of age (15 mGy) was found to be inadequate for acceptable reproduction of low-contrast structures.