基于MVCT图像引导技术的全身一体化固定板在全中枢螺旋断层放射治疗中的固定效果

Fixation effect of whole-body fixation plate based on MVCT imageguided technique in craniospinal tomotherapy

目的:应用螺旋断层放射治疗系统的兆伏级CT(megavoltage CT,MVCT)图像引导技术来分析全身一体化固定板在全中枢放疗中的固定效果。方法:回顾性分析10例全中枢放疗患者的摆位误差。所有患者均取仰卧位,并采用全身一体化固定板结合热塑网膜对其进行体位固定。对螺旋断层放射治疗前采集的MVCT图像与定位时的千伏级CT(kilovoltage CT,KVCT)图像进行匹配,从而获得6个自由度方向上的摆位误差。匹配满意后可进行螺旋断层放射治疗;如果匹配不满意,并经放疗科临床医师确认后,需要对患者进行二次摆位。结果:对10例患者共采集159次MVCT图像。左右(left-right,LR)、头足(cranial-caudal,CC)、腹背(anterior-posterior,AP)、pitch、roll和yaw方向上的摆位误差分别为(1.94±1.44)mm、(2.98±2.51)mm、(1.71±1.87)mm、(0.73±0.64)°、(0.30±0.26)°和(0.34±0.31)°。需要进行二次摆位的次数为5次(3.14%)。结论:MVCT图像引导技术可以显著减少全中枢放疗患者的摆位误差。仰卧位全身一体化固定板在全中枢螺旋断层放射治疗中的固定效果是可以被接受的。

Objective： Application of tomotherapy with megavoltage CT （MVCT） image-guided technique into craniospinal radiotherapy to analyze the fixation effect of whole-body fixation plate. Methods： A retrospective analysis of 10 cases receiving craniospinal radiotherapy was performed.All patients were in supine position and were fixed with a whole-body fixation plate combined with thermoplastic mesh.The MVCT images acquired before tomography were matched with the kilovoltage CT （KVCT） images,so that the setup errors in six directions were detected.The tomography was performed if the matching result was satisfactory,otherwise the patient needed to be setup for the second time when the matching result was not accepted by the clinical radiation therapists. Results： A total of 159 MVCT scans was conducted in 10 patients.The average setup errors in left-right （LR）,cranial-caudal （CC）,anterior-posterior （AP）,pitch,roll and yaw directions were （1.94±1.44） mm,（2.98±2.51） mm,（1.71±1.87） mm,（0.73±0.64） degrees,（0.30±0.26） degrees and （0.34±0.31） degrees,respectively.The probability of second setup was 3.14%（5/159）. Conclusion： MVCT image-guided technique can significantly reduce the setup errors in craniospinal tomography.The fixation effect of the whole-body fixation plate is acceptable.