食管癌三维适形放疗中摆位误差对剂量学影响的研究  

Impact of setup errors on dose distribution of three dimensional conformal radiotherapy for patients with esophageal carcinoma

作　　者：高超[1] 王澜[1] 迟子锋[1] 韩春[1] 王军[1] 张辛[1] 麻国新[1] 肖爱勤[1] 

机构地区：[1]河北医科大学第四医院放疗科,石家庄050011

出　　处：《中华放射肿瘤学杂志》2009年第4期270-273,共4页Chinese Journal of Radiation Oncology

基　　金：河北省强势特色学科课题（冀教高[2005]52号）

摘　　要：目的测量食管癌患者三维适形放疗过程中的摆位误差，分析摆位误差对大体肿瘤体积（GTV）、临床靶体积（CTV）和周围正常组织受照剂量的影响，探讨计划靶体积（町V）外放范围的合理l生。方法对42例食管癌患者用电子射野影像装置测量其摆位误差，每例患者接受摆位验证6次（1次／周）。在治疗计划系统上模拟实际摆位误差，评价实际治疗过程中GTV、CTV和周围正常组织的受照剂量。结果42例食管癌患者左右、前后、头脚方向摆位系统误差分别为-2．31、-0．55、-0．16mm，随机误差分别为4．42、4．35、4．48mm。摆位误差使食管癌患者GTV95％体积接受的剂量（D95）与原治疗计划相比降低了32cGy，CTV D95降低了88cGy。原计划和结合摆位误差计划的全肺接受20Gy照射体积占全啼体积的百分比（V20）分别为22．49％和22．02％，心脏平均剂量分别为2077．62cGy和2036．23cGy。原计划中无一脊髓受量超过4500cGy，结合摆位误差计划中18例脊髓最大剂量超过4500cGy，其中1例最大剂量为5503．90cGy。结论摆位误差使GTV、CTV的受照剂量有所下降，双肺、心脏受照剂量未见明显变化，部分患者脊髓最大剂量超过耐受量。Objective To measure the setup errors of patients with esophageal carcinoma during the treatment of three dimensional conformal radiotherapy （3DCRT） , and to analyze the impact of setup errors on dose distribution of GTV, CTV and normal tissues around. Methods Forty-two patients with esophageal cancer treated by 3DCRT were included. The setup errors of each patient were measured once a week for 6 times by electronic portal imaging device （EPID）. The setup errors were integrated into the treatment planning system by moving the isocenter. Then the dose distribution of GTV, CTV and normal tissues were recalculated. Results The systematic setup errors of the 42 patients were - 2.31 mm, - 0.55 mm and - 0.16 mm, and the random errors were 4.42 mm, 4.35 mm and 4.48 mm in the directions of left-right, anteriorposterior,and superior-inferior, respectively. The dose covered 95% GTV（D95 ） was reduced by 32 cGy and by 88 cGy for CTV D95. The lung V20 in the original plan and the integrated plan was 22.49% and 22.02% , respectively. The average dose of the heart in the two plans was 2077.62 cGy and 2036.23 cGy, respectively. In the original plan, no patient had maximum dose of spinal cord over 4500 cGy ; While in the intergrated plan there were 18 patients had the spinal cord dose more than 4500 cGy, with a maximum dose of 5503.90 cGy. Conclusions The setup errors cause significant dose reduction of GTV and CTV, but not of the lung and heart . The maximum dose of the spinal cord may exceed 4500 cGy due to the setup errors.

关 键 词：食管肿瘤/放射疗法 放射疗法 三维适形 摆位误差 剂量学 

分 类 号：R686[医药卫生—骨科学]