前列腺癌影像引导放疗中电子射野影像装置和经会阴超声实时位置验证方法比较

Comparison of Real Time Position Verification of Electronic Portal Imaging Device Versus Trans-Perineal Ultrasound in Image Guided Radiotherapy for Prostate Cancer

[目的]比较电子射野影像装置(electronic portal imaging device,EPID)和Clarity经会阴超声(trans-perineal ultrasound,TPUS)在基于黄金基准标志物的前列腺癌影像引导放疗(IGRT)中靶区实时位置验证效能。[方法]筛选符合标准的前列腺癌患者10例,接受治疗前锥形束CT验证以确保前列腺癌IGRT分次治疗间靶区位置准确性;之后接受治疗中实时EPID和TPUS成像,分别采用Bland-Altman法和独立样本t检验评价两种成像方法对前列腺癌IGRT分次治疗内靶区位置验证一致性和差异。[结果] TPUS和EPID位置验证数值在左右、头脚、腹背3个方向上具有中度以上相关性(r=0.879、0.645、0.531)。3个方向上TPUS位置验证数值显著性小于EPID[(0.32±0.20)mm vs (0.51±0.33) mm,(0.41±0.31) mm vs (0.63±0.48) mm,(0.46±0.38) mm vs (0.72±0.45) mm,P均<0.05]。TPUS和EPID记录的总位移时间呈弱相关(r=0.482),且一致性较差。TPUS记录的总位移时间显著性少于EPID[(2.27±0.95) min vs (4.38±1.39) min,P<0.05]。[结论]相比较EPID,TPUS综合优势更明显,更适合用于治疗中前列腺癌靶区实时位置验证。

[Objective] To compare the real time position verification efficiency of elekta electronic portal imaging device(EPID) and clarity trans-perineal ultrasound(TPUS) in image guided radiotherapy(IGRT) for prostate cancer based on gold fiducial marker. [Methods] Ten prostate cancer patients who met the inclusion-exclusion criteria were selected and verified by cone beam CT before treatment to ensure the accuracy of target position between fraction treatments in prostate cancer IGRT. The real time EPID and TPUS images were obtained during treatment, and the consistency and difference of the two imaging methods for verification of target position in intra-fraction therapy of IGRT were evaluated by using Bland-Altman method and independent sample t-test respectively. [Results] The correlation of TPUS and EPID position verification values in left-right, head-foot, abdomen-back directions was above moderate(r=0.879, 0.645, 0.531). TPUS position verification value was significantly less than EPID in three directions [(0.32±0.20) mm vs(0.51±0.33) mm,(0.41±0.31) mm vs(0.63±0.48) mm,(0.46±0.38) mm vs(0.72±0.45) mm, all P<0.05]. The total displacement time recorded by TPUS and EPID showed weak correlation and poor consistency(r=0.482). The total displacement time recorded by TPUS was significantly less than EPID [(2.27±0.95) min vs(4.38±1.39) min, P<0.05]. [Conclusion]Compared with EPID, TPUS has significant comprehensive advantages and is more suitable for real time target position verification in IGRT for prostate cancer.