Department of Radiology, Hallym University Sacred Heart Hospital, Anyang 431-070, Korea.
Korean J Radiol. 2013 May-Jun;14(3):525-31. doi: 10.3348/kjr.2013.14.3.525. Epub 2013 May 2.
To determine the optimum low dose (LD) digital tomosynthesis (DT) setting, and to compared the image quality of the LD DT with that of the standard default (SD) DT.
Nine DT settings, by changing tube voltage, copper filter, and dose ratio, were performed for determining the LD setting. Among combinations of DT setting, a condition providing the lowest radiation dose was determined. Eighty artificial nodules less than 1 cm in diameter (subcentimeter nodules: 40, micronodules less than 4 mm: 40) were attached to a Styrofoam and a diaphragm of the phantom. Among these, 38 nodules were located at the periphery of the lung (thin area) and 42 nodules were located at the paravertebral or sub-diaphragmatic area (thick area). Four observers counted the number of nodules detected in the thick and thin areas. The detection sensitivity in SD and LD settings were calculated separately. Data were analyzed statistically.
The lowest LD setting was a combination of 100 kVp, 0.3 mm additional copper filter, and a 1 : 5 dose ratio. The effective dose for the LD and SD settings were 62 µSv and 140 µSv, separately. A 56.7% dose reduction was achieved in the LD setting compared with the SD setting. Detection sensitivities were not different between the SD and the LD settings except between observers 1 and 2 for the detection of micronodules in the thick area.
LD DT can be effective in nodule detection bigger than 4 mm without a significant decrease in image quality compared with SD DT.
确定最佳低剂量（LD）数字断层融合摄影（DT）设置，并比较 LD DT 与标准默认（SD）DT 的图像质量。
通过改变管电压、铜滤过器和剂量比，对 9 种 DT 设置进行了研究，以确定 LD 设置。在 DT 设置组合中，确定了提供最低辐射剂量的条件。将 80 个直径小于 1 厘米的人工结节（亚厘米结节：40 个，直径小于 4 毫米的微结节：40 个）附着在一个泡沫塑料和一个模体的膈肌上。其中，38 个结节位于肺的周边（薄区），42 个结节位于椎旁或膈下区（厚区）。4 名观察者分别对厚区和薄区的结节数量进行计数。分别计算 SD 和 LD 设置的检测灵敏度。对数据进行统计学分析。
最低 LD 设置为 100 kVp、0.3 毫米附加铜滤过器和 1:5 剂量比的组合。LD 和 SD 设置的有效剂量分别为 62 µSv 和 140 µSv。与 SD 设置相比，LD 设置的剂量减少了 56.7%。除了观察者 1 和 2 对厚区微结节的检测外，SD 和 LD 设置之间的检测灵敏度没有差异。
与 SD DT 相比，LD DT 可以在不显著降低图像质量的情况下有效检测大于 4 毫米的结节。
