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目的:通过对聚甲基丙烯酸甲酯(PMMA)模体行离线模式下PET/CT显像，探讨PET-边界验证方法(PET-RV)用于定量分析质子放疗精准性的可行性。方法:在PMMA模体上分别给予2 Gy和4 Gy的照射剂量，对每个剂量组根据临床靶区(CTV)的不同，以2.5 cm为步进分别设计7个照射深度组(5.0、7.5、10.0、12.5、15.0、17.5、20.0 cm)，共14个照射计划(14组照射野)。以能量在48～221 MeV之间的质子束照射，照射结束后10 min左右进行PET/CT显像。对PET/CT数据分别进行图像配准、平滑和约化等预处理，然后利用Raystation PET-RV软件对图像进行感兴趣区(ROI)的确定和采样线的抽提，通过生成的预测感生放射性活度与实际采集感生放射性活度采样线计算Δn R50，即2条曲线末端在最大预测感生放射性活度最大值下降一半(n V50)处对应的空间位置差异。n 结果:每个照射野的ROI均为5.0 cm×5.0 cm×2.5 cm的立方体，采样线在其内间隔3 mm均匀分布，共得到289组采样线。14组数据经分析后得到的Δn R50(深度差异)均值都处于-1～1 mm之间。n 结论:离线模式下PET/CT显像示PET-RV算法对PMMA模体质子放疗空间位置差异的验证精度在1 mm之内，可以满足后期对临床病例分析的精度要求。“,”Objective:To test the usefulness of PET-range verification (RV) method for proton radiation accuracy verification in poly (methyl methacrylate) (PMMA) phantom using off-line PET/CT scanning.Methods:Proton irradiation dose of 2 Gy and 4 Gy were delivered in PMMA phantom. Given the difference of clinical target volume (CTV), 7 subgroups with different depth (5.0, 7.5, 10.0, 12.5, 15.0, 17.5, 20.0 cm) were set for each dose (14 radiation plans or radiation fields). PET/CT scan was performed 10 min after irradiation of 48-221 MeV proton beam. A co-registration between CT from treatment planning system and PET/CT was performed, as well as the smoothing and normalization of PET/CT data. The region of interest (ROI) and profile lines were drawn with the Raystation PET-RV software. The predictive induced radioactivity and the measured induced radioactivity profile lines were analyzed to evaluate the Δ n R50, namely, the error at the position corresponding to 50% of the maximum predictive induced radioactivity at the end of both curves.n Results:The size of each ROI was 5.0 cm×5.0 cm×2.5 cm. Profile lines were evenly distributed with the interval of 3 mm, and totally 289 pairs of profile lines were drew. The 2 Gy- and 4 Gy-dose groups yielded similar mean depth errors (Δn R50 between 1 mm and -1 mm with a standard deviation <1 mm).n Conclusions:The off-line PET/CT scanning of PMMA phantom reveals a good agreement between predicted and measured PET data, with error of ±1 mm. The PET-RV method can be extended to clinical cases′ verification in human body treatment with further investigation.