Mu Xiangkui, Olofsson Lennart, Karlsson Mikael, Sjögren Rickard, Zackrisson Björn
Department of Radiation Sciences, Oncology, Umeå University, Umeå, Sweden.
Acta Oncol. 2004;43(8):727-35. doi: 10.1080/02841860410002761.
Conformal radiotherapy or intensity modulated radiotherapy (IMRT) commonly leads to a large integral dose in the patient. Electrons would reduce the integral dose but are not suitable for treating deep-seated tumours, owing to their limited penetration. By combining electron and photon beams, the dose distributions may be improved. In this study, the possibility is explored of using a mixture of electron and photon beams for a deep-seated target volume in the head and neck region. Treatment plans were made for five simulated head and neck cancer cases. Mixed electron and photon beam plans (MB) were constructed using a manual iterative procedure. Photon IMRT plans were optimized automatically. Both electron and photon beams were collimated by a computer controlled multi-leaf collimator (MLC). Both methods were able to produce clinically acceptable plans. Criteria for the target dose were met similarly by both as were the criteria for critical organs. The integral dose outside the planning target volume (PTV) showed a tendency to be lower with MB plans compared with photon IMRT plans. A mixed electron and photon technique has the potential to treat deep-seated tumours. It is reasonable to expect that if computerized optimization tools were coupled with the mixed electron and photon beam technique, treatment goals would be more readily achieved than if using solely pure photon IMRT.
适形放疗或调强放疗（IMRT）通常会使患者体内产生较大的积分剂量。电子束可以降低积分剂量，但由于其穿透能力有限，不适用于治疗深部肿瘤。通过结合电子束和光子束，可以改善剂量分布。在本研究中，探讨了使用电子束和光子束的混合束治疗头颈部区域深部靶区的可能性。针对五例模拟头颈部癌病例制定了治疗计划。混合电子束和光子束计划（MB）采用手动迭代程序构建。光子IMRT计划自动优化。电子束和光子束均由计算机控制的多叶准直器（MLC）准直。两种方法都能够产生临床可接受的计划。两种方法在靶区剂量标准和危及器官标准方面的满足情况相似。与光子IMRT计划相比，MB计划在计划靶区（PTV）外的积分剂量有降低的趋势。电子束和光子束混合技术有治疗深部肿瘤的潜力。可以合理预期，如果将计算机优化工具与电子束和光子束混合技术相结合，将比单纯使用光子IMRT更容易实现治疗目标。
