宫颈癌常规放射野的修正

Correction of Conventional Radiation Field in Cervical Cancer

目的通过CT三维重建标示盆腔血管分叉处及X线下测量阴道顶端制定合理的放射野。分析体质指数、宽棘比、髋高比与盆腔放射野是否存在关联。方法 CT三维重建血管,标示相关血管分叉处,测量血管分叉与所对应常规放射野的边界的距离,X线机下测量20例宫颈癌术后患者阴道顶端与耻骨联合上缘的距离,制定更为合理的放射野。采用逐步回归分析体质指数、髂高比、宽棘比与盆腔放射野的关系。结果定位L4、5椎体间隙基本上包含了大部分左右髂总动脉分叉。腹主动脉分叉位于L4、5椎体间隙4例(9%),L4椎体中心处41例(63%),L3、4椎体间隙14例(22%),L3、4椎体间隙以上4例(6%)。左侧外移至骨盆外2.2cm时,合适侧界所占比例达到最大(63%)。右侧骨盆外移至2.4cm时,合适侧界所占比例达到最大(62%)。19例(75%)好位于耻骨联合上缘下方2cm。体质指数与放射野的相关测距没有任何相关性,其余参数与放射野的相关测距无相关性,但意义不大。结论放射野上界位于L4、5椎体间隙包含大部分髂总动脉分叉,如髂总淋巴结转移,上界需要上移至L3、L4之间,少部分甚至需要上移更高位置,左侧界应移至骨盆外2.2cm,右侧界应移至骨盆外2.4cm,下界应位于耻骨联合上缘下方2cm。

Objective To formulate the reasonable radiation field by CT three-dimensional re-construction of pelvic vascular bifurcation and X-ray measure of vaginal apex,and to analyze the relationships of body mass index,width spin ratio and hip high specific to pelvic radiation field. Methods The distance between vascular bifurcation and boundary of conventional radiation field was measured by CT three-dimensional reconstruction and the distance between vaginal apex and superior margin of pubic symphysis was measured by X-ray in 20 cervical cancer patients to for-mulate a more reasonable radiation field.The stepwise regression procedure was used to analyze the relationships of body mass index,width spin ratio and hip high specific to pelvic radiation field.Results The localization of L4-5 vertebral clearance basically contained most of iliac artery bifurcations.Abdominal aortic bifurcation was located at L4-5 vertebral clearance in 4 cases （9%）,at the center of L4 vertebral body in 41 cases （63%）,at L3-4 vertebral clearance in 14 ca-ses （22%）,and above L3-4 vertebral clearance in 4 cases （6%）.The maximum proportion of the reasonable lateral boundary was achieved when the left side of the sector moved outside the pelvis 2.2 cm （63%）and the right side of the sector moved outside the pelvis 2.4 cm （62%）.The vagi-nal apex of 19 patients was located at 2 cm under the superior border of pubic symphysis.Hip high specific and width spin ratio,but not body mass index,were not correlated with the measure-ment of radiation field.Conclusion The upper bound of radiation field at L4-5 vertebral space contains most of the common iliac artery bifurcations.Such as the common iliac lymph node me-tastasis,upper bound needs to be moved to L3-4 vertebral space,and a small part even needs to be moved to higher position.In addition,the left side of the sector should be moved outside the pelvis 2.2 cm,the right side of the sector should be moved outside the pelvis 2.4 cm,and the lower bound should be located at 2 cm below the upper edge of pubic symphysis.