87例乳腺肿瘤三维适形放疗临床靶区到计划靶区外扩边界的修正研究

Research on Referential Safety Margins Modification of CTV to PTV Study in 87 Breast Cancer Cases of Three-dimensional Conformal Radiotherapy Target Volume Breast Cancer

目的：研究乳腺肿瘤三维适形放疗临床靶区（ CTV）到计划靶区（ PTV）外扩边界的范围。方法对2013－01～2013－12间我院应用三维适形放疗的87例乳腺肿瘤患者进行复位前后和第N次（ N为随机量）治疗前后选取固定正、侧位野拍摄等距离验证片各1张，运用HW－TPSQA软件与计划系统中的照射野数字重建影像进行比较，得出摆位误差。每例患者各个方向的摆位系统误差以Σ表示，摆位随机误差以σ表示，放疗靶区CTV到PTV外扩边界的范围以SCTV→PTV表示，依据Van Herk等推导公式SCTV→PTV ＝2.5Σ＋0.7σ。结果乳腺肿瘤三维适形放疗靶区CTV外扩PTV边界范围的参考数据：胸部X、Y、Z方向外扩边界参数分别为2.36 mm、4.04 mm、3.69 mm。结论本研究为乳腺肿瘤三维适形放射治疗CTV外扩PTV边界范围的确定和修正提供了有效的理论依据，降低了肿瘤靶区遗漏的可能性，使得肿瘤三维精确适形放射治疗的优越性得到充分的发挥。

Objective To study the reference data of referential safety margins of CTV to PTV in Three -dimensional Conformal Radio-therapy target volume with breast cancer.Methods The translational deviation of 87 breast cancer patients during Jan.and Dec.in 2013 were examined in the study.Vacuum cushion was used for chest and abdomen immobilization.The verification films were taken for each pa-tient prior the first treatment and the Nth were compared with the digitally reconstructed radiographs （DRR） by the HW-TPSQA system, in order to make translational deviation.CTV margin should be calculated with the formula 2.5Σ＋0.7σby Van Herk al.Σmeans Systematic Error,σmeans Random Error.Results The margin of PTV of chest in three directions （x, y, z） was 2.36mm, 4.04 mm and 3.69 mm.Conclusion It has laid a theoretic foundation for the CTV margins by analyzing the translational deviation and made the design of radio -therapy system more scientific and normal in Three -dimensional Conformal Radiotherapy target volume with breast cancer.