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目的:评价锥形束CT(CBCT)在线调整技术在大分割治疗椎体转移瘤中的应用价值。评价分次间摆位误差及治疗过程中靶区位移对治疗的影响。方法:2008年12月至2009年08月,应用医科达Synergy系统治疗椎体转移瘤10例,每次照射前、调整后及治疗后获取CBCT图像,将获取图像和计划CT图像匹配,获得靶中心X(左右)、Y(头脚)、Z(前后)方向的位移及旋转角度误差,分析误差及分布规律。应用逆向调强放射治疗技术,靶区剂量63Gy/9次,隔日照射。随访6个月。结果:10例患者共10个靶区CBCT扫描269次。首次摆位在X、Y、Z方向位移误差分别为(-0.90±4.20)mm、(-0.40±4.90)mm、(-2.50±3.40)mm,旋转角度误差分别为(-0.20±1.65)°、(-1.12±1.84)°、(0.22±1.48)°。调整后其位移误差分别为±0.80mm、±0.90mm、(-0.10±0.80)mm;治疗后分别为(-0.10±1.30)mm、±1.80mm、(0.10±1.40)mm。调整后角度误差分别为(-0.21±1.06)°、(-0.72±0.96)°、(0.33±0.85)°;治疗后分别为(-0.15+1.27)°、(-0.64±1.39)°、(0.62±1.18)°。调整前PTV外扩值范围为8.40～11.00mm,调整后缩小为1.20～1.50mm。10例患者疼痛缓解,未发现放疗副作用。治疗6个月后复查骨扫描提示核素浓聚减少。结论:CBCT在线调整能纠正摆位误差,既满足靶区剂量的提升也有效降低了脊髓受量。高剂量大分割图像引导调强放疗技术是治疗椎体转移瘤的一种安全、有效的新方法。
Objective: To evaluate the value of on-line calibration of cone beam CT (CBCT) in the treatment of vertebral metastases by large segmentation. Evaluation of sub-set error and target position during the treatment of the impact of treatment on the treatment. Methods: From December 2008 to August 2009, 10 cases of vertebral metastases were treated with Synergy Syndrome system. Before each irradiation, CBCT images were obtained after adjustment and after treatment. The acquired images and planned CT images were matched to obtain the target Center X (left), Y (head), Z (front and rear) direction of the displacement and rotation angle error, analysis of error and distribution. The application of reverse-modulated radiotherapy technology, target dose 63Gy / 9 times, every other day irradiation. Follow up for 6 months. Results: Ten patients had 10 CBCT scanning targets in 269 times. The displacement errors for the first position in the X, Y and Z directions were (-0.90 ± 4.20) mm, (-0.40 ± 4.90) mm and (-2.50 ± 3.40) mm, respectively. The error of rotation angle was -0.20 ± 1.65 , (-1.12 ± 1.84) °, (0.22 ± 1.48) °. After adjustment, the displacement errors were ± 0.80mm, ± 0.90mm and (- 0.10 ± 0.80) mm respectively. After treatment, they were (-0.10 ± 1.30) mm, ± 1.80mm and (0.10 ± 1.40) mm, respectively. (-0.21 ± 1.06) °, (-0.72 ± 0.96) ° and (0.33 ± 0.85) ° respectively after treatment; (-0.15 ± 1.27) ° and (-0.64 ± 1.39) ° respectively after treatment 0.62 ± 1.18) °. Before adjustment, the range of PTV external expansion is 8.40 ~ 11.00mm, adjusted and reduced to 1.20 ~ 1.50mm. Ten patients had pain relief and no radiotherapy side effects were found. A review of bone scans after 6 months of treatment suggested a decrease in nuclide concentrations. Conclusion: The on-line adjustment of CBCT can correct the setup error, which not only meets the requirement of target dose but also decreases the volume of spinal cord. High-dose large segmented image-guided intensity modulated radiotherapy is a safe and effective new method for the treatment of vertebral metastases.