自动管电流调制技术在PET/CT中的实际应用

目的 探讨自动管电流调制（ATCM）技术对PET/CT受检者CT图像质量及有效剂量的影响。 方法 将2017年10月至2018年7月接受PET/CT检查的90例受检者按系统抽样方法分为A、B、C 3组，每组各30例。CT采用ATCM扫描。A、B两组采用的管电流区间为60~240 mA，噪声指数分别为10、15；C组管电流区间为60~180 mA，噪声指数为15。记录容积CT剂量指数（CTDI_vol）和剂量长度乘积（DLP），根据公式估算有效剂量。由两位核医学科主治及以上医师采用双盲法对受检者颈部、胸部、腹部、盆腔CT图像质量进行评分，测定图像CT值、噪声值并计算信噪比。采用方差分析比较3组的噪声值、信噪比差异，采用非参数检验中的Kruskal-Wallis检验比较3组的CTDI_vol、DLP、有效剂量差异，组内两两比较采用Nemenyi检验。 结果 A、B、C 3组受检者所有图像质量评分均不低于3分，且差异均有统计学意义(F=3.77~14.42，均P<0.05)。A、B、C 3组受检者的噪声值（11.90±2.83）~（26.03±3.74）]、信噪比（2.03±0.34）~（4.35±0.71）]差异均有统计学意义（F=38.01~64.20和F=32.09~81.62，均P<0.05），CT图像质量均能满足临床诊断要求。A、B、C 3组受检者的CTDI_vol（12.44±0.53）、（9.39±2.01）和（7.05±1.03）mGy]、DLP（998.45±96.04）、（741.60±168.87）和（571.29±97.41） mGy·cm]、有效剂量（14.98±1.44）、（11.12±2.53）和（8.57±1.46） mSv]的差异均有统计学意义（χ2=62.18、57.19和57.16，均P<0.05）。其中，C组比A组的有效剂量低，差异有统计学意义（χ2=56.55，P<0.05）。 结论 应用PET/CT ATCM技术，合理调节管电流区间及噪声指数，保证图像质量的同时可有效降低受检者的有效剂量。

Application of automatic tube current modulation technology in PET/CT

Objective To investigate the effects of automatic tube current modulation (ATCM) on CT image quality and effective dose(ED) of PET/CT of 90 patients. Methods PET/CT of 90 patients from October 2017 to July 2018 were randomly divided into three groups, A, B, and C by systematic sampling(30 cases in each group), and CT was scanned by ATCM. The tube current interval of group A and B was 60–240 mA, and the noise index(NI) was 10 and 15; the tube current interval of group C was 60–180 mA, and the NI was 15. The CT volume dose index(CTDI_vol) and dose length product(DLP) were recorded, and the ED was estimated according to the formula. The CT image quality of neck, chest, abdomen, and pelvis were evaluated blindly by two and above attending physicians in nuclear medicine to calculate signal-to-noise ratio(SNR) by measuring CT value and noise value of the CT image. Noise value and SNR were compared with variance analysis. CTDI_vol, DLP, and ED were compared with Kruskal-Wallis and with Nemenyi in pairs. Results Differences in noise value(11.90±2.83)–(26.03±3.74)] and SNR (2.03±0.34)–(4.35±0.71)] among three groups were statistically significant (F=38.01–64.20, F=32.09–81.62, and all P<0.05), and the CT image quality met the clinical diagnostic requirements. CTDI_vol were (12.44±0.53), (9.39±2.01), and (7.05±1.03) mGy, DLP were (998.45±96.04), (741.60±168.87), and (571.29±97.41) mGy·cm, and ED were (14.98±1.44), (11.12±2.53), and (8.57±1.46) mSv among three groups, with statistically significant differences(χ2=62.18, 57.19, 57.16, and all P<0.05). Group C was lower than group A(χ2=56.55, P<0.05) with statistically significant differences. Conclusion ATCM technology can ensure the image quality while reducing the ED effectively by modulating the current interval and NI reasonably.