基于不同附加滤过的腹部数字X射线摄影图像质量的优化研究

目的 探讨不同附加滤过对腹部数字化X射线摄影影像质量和辐射剂量的影响。方法 回顾性分析首都医科大学附属复兴医院2020年12月至2021年1月10例行腹部X射线摄影的患者病例资料。采用自动曝光控制（AEC）技术，用获得相同mAs时的对应厚度（18 cm）的有机玻璃作为模拟腹部的衰减体。将CDRAD 2.0模体和17块10 mm厚的PMMA板（总厚度18 cm）置于检查床上，附加滤过分别选择无附加滤过、2 mmAl、0.1 mmCu+1 mmAl、0.1 mmCu+2 mmAl，电离室等级分别选择-2、-1、0、1、2时进行曝光，采集图像并使用CDRAD 2.0模体软件进行分析，得到影像质量因子（IQF_inv）。根据不同附加滤过将影像质量因子分组，测量每次曝光时模体表面的入射空气比释动能，使用PCXMC软件估算器官剂量和有效剂量，并进行比较分析。结果 无附加滤过、2 mmAl、0.1 mmCu+1 mmAl、0.1 mmCu+2 mmAl的皮肤入射剂量分别为（0.546 1±0.200 8）、（0.376 2±0.133 8）、（0.285 3±0.100 1）和（0.289 9±0.099 2） mGy，有效剂量估算值分别为（79.63±29.24）×10^-3、（71.05±25.56）×10^-3、（63.58±22.18）×10^-3和（67.64±23.11）×10^-3mSv，性腺器官剂量分别为（0.058 1±0.020 8）、（0.050 0±0.018 0）、（0.044 8±0.015 6）和（0.047 7±0.016 3） mGy，IQF_inv值分别为4.70±0.61、4.80±0.84、4.60±0.55和4.60±0.60。在不同附加滤过下，有效剂量与皮肤入射剂量呈线性相关，表面入射剂量增加则有效剂量增加，0.1 mmCu+1 mmAl附加滤过时剂量最低，组间IQF_inv差异无统计学意义（P>0.05）。结论 腹部X射线摄影最适宜的附加滤过为0.1 mmCu+1 mmAl，此时图像质量能满足临床诊断需求，辐射剂量得到合理降低，达到了摄影参数最优化的目的。

Study on image quality optimization of abdominal digital radiography with different additional filters

Objective To investigate the effect of different additional filters on the image quality and radiation dose in abdominaldigital radiography (DR). Methods Retrospective analysis was performed on 10 cases of abdominal DR from December 2020 to January 2021 in Fuxing Hospital, and the average mAs was calculated. Using automatic exposure control (AEC) technology, a polymethyl methacrylate (PMMA) slab of the corresponding thickness (18 cm) at the same output of above mAs was confirmed and used as the attenuator to simulate the abdomen. The phantom of CDRAD 2.0 and 17 slices of 10 mm thick PMMA plates (total thickness 18 cm) were placed on the bed. The additional filters were selected as no additional filter,2 mmAl,0.1 mmCu+1 mmAl, 0.1 mmCu+2 mmAl respectively. The AEC levels were selected at -2, -1, 0, 1, and 2 respectively. The images were collected and analyzed by using CDRAD 2.0 software to obtain the image quality factor (IQF_inv). The incident air kinetic energy on the surface of the PPMA was measured for each exposure, and PCXMC software was used to estimate the organ dose and effective dose, and a comparative analysis was made. Results The skin incident doses at no additional filter, 2 mmAl, 0.1 mmCu+1 mmAl,0.1 mmCu+2 mm Al were (0.546 1±0.200 8), (0.376 2±0.133 8), (0.285 3±0.100 1) and (0.289 9±0.099 2) mGy, respectively. The estimated effective doses were (79.63±29.24)×10^-3, (71.05±25.56)×10^-3, (63.58±22.18)×10^-3 and (67.64±23.11)×10^-3 mSv, respectively. The gonadal doses were (0.058 1±0.020 8), (0.050 0±0.018 0), (0.044 8±0.015 6) and (0.047 7±0.016 3) mGy.The IQF_inv values were 4.70±0.61, 4.80±0.84, 4.60±0.55, 4.60±0.60, respectively. There were linear correlations between the effective dose and the skin incident dose under different additional filtration, and the effective doses increased with the increase of the incident doses. The dose was lowest at the addition filtration of 0.1 mmCu+1 mmAl. There was no significant difference in the IQF_inv between groups(P>0.05). Conclusions The optimal additional filtration for abdominal DR was 0.1 mmCu+1 mmAl with the image quality meeting the requirements of clinical diagnosis, the radiation dose reduced reasonably, and the objective of the optimization of radiographic parameters achieved.