头颈部肿瘤放疗过程中腮腺变化对照射剂量影响的研究  

Position modification and actual radiation dose in parotids for head and neck cancers treated with TomoTherapy

作　　者：蒋华勇[1] 张勇乾[1] 王雅棣[1] 许卫东[1] 高军茂[1] 张富利[1] 姚波[1] 

机构地区：[1]北京军区总医院放疗科,100700

出　　处：《中华放射医学与防护杂志》2014年第11期845-849,共5页Chinese Journal of Radiological Medicine and Protection

摘　　要：目的 分析头颈部肿瘤患者螺旋断层放疗过程中腮腺位置、体积变化对受照剂量的影响，方法 12例头颈部肿瘤根治性放疗患者,每次治疗前行MVCT图像配准,选择每周第1天MVCT图像,应用TomoTherapy系统自带软件和MIM系统,计算腮腺体积、位置变化和实际照射剂量，结果 与初始计划相比,放疗结束时左、右两侧腮腺体积分别缩小29.06％和31.78％ （Z=6.77、3.06,P＜0.05）,腮腺质心距离体中线距离分别缩小6.72％和6.19％（=5.14、5.80,P＜0.05），治疗过程中左侧腮腺V26、平均剂量分别增加37.74％、25.08％（Z=-6.03、-5.31,P＜0.05）,右侧腮腺V26、平均剂量分别增加30.45％、19.33％（Z=-5.43、-3.26,P＜0.05），结论 头颈部肿瘤放疗过程中腮腺实际受照剂量较初始计划明显升高,剂量升高与腮腺向体中线位移密切相关,与腮腺体积缩小无明显相关性，适时重新制定放疗计划或行自适应放疗,可减少腮腺受照剂量。Objective To analyze the impact of parotid′s position and volume changing on radiation dose for head and neck cancer treated with TomoTherapy.Methods Totally 12 patients with head and neck cancer were treated with TomoTherapy.Before the treatment,the dose distribution was recalculated with MVCT images,which would obtain the parameters of position,volume and actual radiation dose for parotids.Results The volume of parotids in Plan2 was significantly lower than in Plan1,and the percentage reduction was 29.06% and 31.78% for left and right parotid,respectively （Z =6.77,3.06,P 〈 0.05）.Distance between the COM （center of mass） of parotids and the midline of body was significantly smaller in Plan2 than in Plan1,and the percentage reduction was 6.72% and 6.19% （t =5.14,5.80,P 〈 0.05） at left and right side,respectively.Average dose and V26 for both parotids were higher than those in Plan1,increasing by an average of 37.74%,25.08% （Z =-6.03,-5.31,P 〈 0.05） for left parotid and 30.45%,19.33% （Z =-5.43,-3.26,P 〈0.05） for right parotid,respectively.Conclusions The actual radiation dose to parotids was significantly increased during the radiation therapy for patients with head and neck cancer.There was a linear correlation between the decrease of distance between the COM of parotids and the midline of body and the percentage increase of parotids′ radiation dose.No correlation between the reduction of parotids′ volume and dose to parotids.In order to reduce the parotids′ radiation dose,modification of treatment plan at the appropriate time is essential.

关 键 词：头颈部肿瘤 螺旋断层放疗 腮腺 实际照射剂量 形变图像配准 

分 类 号：R739.91[医药卫生—肿瘤]