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目的了解人体前胸矢状面倾斜度的大小及对放疗剂量分布的影响。方法选择126例患者行胸部CT扫描并予正中矢状面重建。分别测定上中下胸廓层面前后体表中线至脊髓距离及各层上下间距,计算出前胸倾斜度。查TMR表得出中平面深度及脊髓深度处上中胸及中下胸层面剂量误差。结果前野各层面至脊髓距离变化较大,后野变化较小。人体前胸倾斜度范围为25~56°。上中胸段组的上下缘剂量误差较大,躯体中平面平均相差8%,脊髓17%。中下胸段组剂量误差较小,躯体中平面4%,脊髓7%。误差随倾斜角度增加而增加。根据倾斜度得出合适的楔形板修正角度大约为10~35°。结论人体前胸矢状面存在自然倾斜度,这种倾斜影响前野剂量分布,应予以个体化修正。建议根据角度的大小选择合适的头足向楔形板优化。
Objective To understand the size of the sagittal plane of human anterior chest and its influence on the dose distribution of radiotherapy. Methods Totally 126 patients underwent chest CT scan and were reconstructed in midsagittal plane. The upper and lower thoracic surface were measured before and after the body surface to the spinal cord and spinal cord distance between the upper and lower layers to calculate the chest inclination. Check the TMR table to draw the mid-plane depth and spinal cord depth at the middle and lower thoracodilate dose error. Results There was a great change in the distance from the spinal cord to the spinal cord in the anterior field and the change in the posterior field. The inclination of human chest is 25 ~ 56 °. Upper and lower edge of the upper thoracic dose error is larger, the average body surface difference of 8%, 17% of the spinal cord. Lower middle and lower thoracic group dose error smaller body 4% in the plane, spinal cord 7%. The error increases as the tilt angle increases. According to the inclination obtained suitable wedge plate correction angle is about 10 ~ 35 °. Conclusion There is a natural inclination of the sagittal plane of the human body, which affects the dose distribution of the anterior segment and should be individualized. Recommended according to the size of the angle of the appropriate choice of wedge-shaped head plate optimization.