红外线跟踪摆位系统与电子射野影像装置对摆位误差测量结果的比较研究

目的 比较红外线跟踪摆位系统(IM-BPS)和电子射野影像装置(EPID)对食管癌和肺癌患者摆位误差测量结果的优劣。方法 2007-2008年间接受三维适形或调强放疗的40例食管癌和27例肺癌患者,使用IM-BPS和EPID测量其在左右、头脚、前后方向上的摆位误差,并对两种测量结果行配对t检验和符合程度的x2检验。结果 用EPID每例患者摆位验证需10～12 min,而IM-BPS仅需2～5 min。IM-BPS和EPID测量的食管癌患者左右、头脚、前后方向摆位误差均值分别为3.49、3.19、3.31和4.03、3.41、3.43 mm (t=5.17、1.88、1.57,P=0.000、0.060、0.119);肺癌患者的分别为4.23、3.51、3.39 mm和4.85、3.53、3.74 mm (t=5.63、0.28、3.88,P=0.000、0.780、0.000)。≥65％食管癌和≥55％肺癌患者两种测量结果在3个方向摆位误差差值为±1 mm内时差异有统计学意义(x2 =51.09,P=0.000和x2 =53.35,P=0.000)。结论 IM-BPS对食管癌及肺癌患者摆位误差的测量结果大部分优于EPID,虽然两种方法都能对患者治疗摆位进行较为准确测量和质量控制,但因IM-BPS应用直观、简便、耗时短、可实时l监测校正而更易于临床使用。

Comparison of infrared mrker-based positioning system and electronic portal imaging device for the measurement of setup errors

Objective To measure the setup errors with infrared marker-based positioning system (IM-BPS) and electronic portal imaging device (EPID) for patients with esophageal carcinoma and lung cancer and investigate the accuracy and practicality of IM-BPS. Methods From January 2007 to January 2008, 40 patients with esophageal carcinoma and 27 patients with lung cancer received three-dimensional conformal radiotherapy or intensity-modulated radiotherapy, setup errors during the treatment were measured with IM-BPS and EPID, and the data of setup errors were compared with paired t-test and agreement with x2-test. Results It takes 10 - 12 mins to complete the validating for each patient by EPID) system, while IMBPS system only needs 2 -5 mins. The mean setup errors along x, y and z-axis for patients with esophageal carcinoma measured by IM-BPS and EPID were 3.49 mm, 3. 19 mm, 3.31 mm and 4. 03 mm, 3.41 mm, 3.43 mm, respectively. For the patients with lung cancer, the setup errors were 4. 23 mm, 3.51 mm, 3. 39mm and 4. 85 mm, 3. 53 mm, 3.74 mm, respectively. The difference of setup errors meanured by the two systems was within 1 mm for 65％ esophageal carcinoma patients ( x2 =51.09, P =0. 000), and 55％ lung cancer patients ( x2 =53. 35, P =0. 000). Conclusions The measurement results of setup errors for patients with esophageal carcinoma and lung cancer show that IM-BPS is mostly better than EPID. Though validating for patients can be measured accurately and be well quality controlled, IM-BPS is used easily because of macroscopic, homely,spare time and real-time monitoring.