ABSTRACT This study examined the dose and image quality according to the position change of a human phantom in a CT scan. This study used an MDCT 128 Slice CT Scanner instrument. An axial scan was performed with a 16 cm CTDI phantom of a human phantom, and the dose was measured using a pencil chamber meter. The phantom was scanned 10 cm above and below the isocenter and 15 cm above the right and left. The position of the phantom is indicated by C-0 in the isocenter position, S-10 in the upper 10 cm, I-10 in the lower 10 cm, R-15 in the right 15 cm, and L-15 in the left 15 cm. The test was performed 30 times using the brain CT protocol to calculate the dose and the dose width product (DWP). The acquired images were analyzed using the ImageJ program. Statistical analysis was performed using SPSS with one-way ANOVA (p < .05). The mean DWP values of the CT scanner were C-0 31.97 mGy·cm, S-10 24.52 mGy·cm, I-10 24.28 mGy· cm, R-15 17.95 mGy·cm, and L15 17.6 mGy·cm. Compared to the isocenter (C-0), the DLP values measured at each site were 23.3% for S-10, 24% for I-10, 43.8% for R-15, and 44.9% for L15. A significant difference in the one-way ANOVA statistical process was observed (p>0.05). C-0 was measured to be 7.42 HU, S-10 7.87 HU, I-10 8.4 HU, R-15 117 HU, and L-15 13.6 HU for evaluating the image quality. Compared to C-0, S-10 was 5.39%, I-10 was 13.2%, R-15 was 57.6%, and L-15 was 83.2%. The PSNR for S-10, I-10, R-15, and L-15 was 17.37, 17.5, 16.62, and 16.37 dB, respectively. A good quality image can be obtained by positioning the subject precisely in the isocenter in the axial scan, if possible, because the irradiated dose to the subject is low, which can lead to an increase in noise in image reconstruction.

中文翻译：

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轴位扫描型脑CT中体模定心定位对图像噪声和辐射剂量的分析

摘要 本研究根据人体模型在 CT 扫描中的位置变化来检查剂量和图像质量。本研究使用 MDCT 128 切片 CT 扫描仪仪器。使用人体模型的 16 cm CTDI 模型进行轴向扫描，并使用铅笔室测量仪测量剂量。体模在等中心点上方和下方 10 厘米处和左右上方 15 厘米处进行扫描。体模位置用C-0表示等中心位置，S-10表示上10cm，I-10表示下10cm，R-15表示右侧15cm，L-15表示左侧15 厘米。使用脑 CT 协议进行 30 次测试以计算剂量和剂量宽度乘积 (DWP)。使用 ImageJ 程序分析获取的图像。使用 SPSS 和单向方差分析 (p < .05) 进行统计分析。CT扫描仪的平均DWP值为C-0 31.97 mGy·cm、S-10 24.52 mGy·cm、I-10 24.28 mGy·cm、R-15 17.95 mGy·cm和L15 17.6 mGy·cm。与等中心点 (C-0) 相比，在每个站点测量的 DLP 值为 S-10 的 23.3%、I-10 的 24%、R-15 的 43.8% 和 L15 的 44.9%。观察到单向方差分析统计过程的显着差异（p>0.05）。C-0 测量为 7.42 HU、S-10 7.87 HU、I-10 8.4 HU、R-15 117 HU 和 L-15 13.6 HU 用于评估图像质量。与C-0相比，S-10为5.39%，I-10为13.2%，R-15为57.6%，L-15为83.2%。S-10、I-10、R-15 和 L-15 的 PSNR 分别为 17.37、17.5、16.62 和 16.37 dB。如果可能，通过在轴向扫描中将对象精确定位在等中心点可以获得高质量的图像，因为对对象的照射剂量较低，