眼耳平面

Methods: A 3-D coordinate system was designed for skull, based on Frankfurt horizontal plane and analytical geometry method.

以颅骨的耳眼平面为基础定位平面，按解析几何方法设计颅骨的三维空间坐标系。

The raw data was processed by using axial, coronal and double oblique multi-planar reformation; Images obtained were graded in terms of quality with a 5-point scale(5=excellent, 4=good, 3=fair, 2=poor, and 1=nondiagnostic). In grading image quality at axial MPR, The radiologic specialists focused on the subarcuate fossa, tendon of tensor tympani, facial recess, vestibular aqueduct and pyramidal eminence, In grading image quality at coronal MPR, attention was given to the scute, crista transversa, fenestra cochleae, lateral malleal ligament and snake eyes signature of cranial nerve, In the grading of the image quality at double oblique MPR, the radiologic specialists concentrated on the malleus, incus, stirrup bone, upper bony semicircular and aquaeductus fallopii, and then to implement statistical analysis. In order to choose the minimum tube current values and the maximum pitch that can satisfy the diagnosis request, image quality of axial, coronal and double oblique reformation images was compared with different tube current groups. 15 ears of volunteers were used to test the validity with the scanning parameter. Subsequently noise, MTF and dose length product were measured by phantoms in different tube current and pitch, the parameters obtained were compared and taken into statistics analysis.

扫描模式使用临床常用的颞骨螺旋扫描方式：管电压120 kV，准直宽度20×0.6 mm，视野200 mm，重建矩阵512×512，旋转时间1 s/r，重建层厚0.6 mm，重建间隔0.3 mm，分别改变管电流(380、300、200、160、120和80 mA)和螺距(0.8、1.0和1.2)进行扫描和重建，然后对颞骨进行横断面、冠状面和双斜面多平面重组，于重组后的横断层面图像上选取弓形下窝、鼓膜张肌腱、面神经隐窝、前庭导水管和锥隆起5个解剖结构，冠状面重组图像上选取盾板、横嵴、蜗窗、面神经的蛇眼征和锤骨外侧韧带5个解剖结构，双斜面重组图像上选取锤骨、砧骨、镫骨、上骨半规管和面神经管5个解剖结构，在双盲的情况下由放射学专家分别对各管电流和螺距下扫描的重组图像进行评分，随后进行统计学处理，从中筛选出满足诊断要求的最低管电流值和最大的螺距，分别采用患者25例(15耳)用该管电流值和螺距验证其可行性；然后利用模体分别测试各管电流和螺距下的图像的空间分辨率、噪声及其剂量长度积，并对测试所得参数数值进行比较和统计学处理。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。