Department of Radiotherapy and Radio-Oncology, University Medical Center Hamburg-Eppendorf, Germany.
Radiother Oncol. 2010 Mar;94(3):313-8. doi: 10.1016/j.radonc.2009.12.037. Epub 2010 Jan 28.
Conventional irradiation of breast and chest wall tumours may cause high doses in underlying organs. Intensity-modulated radiation therapy (IMRT) with photons achieves high conformity between treated and tumour volume but is associated with considerable low-dose effects which may induce secondary malignancies. We compare treatment plans of electron IMRT to helical photon IMRT and conventional irradiation.
Treatment planning for three patients (breast, chest wall plus lymph nodes, sarcoma of medial chest wall/sternum) was performed using XiO 4.3.3 (CMS) for conventional photon irradiation, Hi-Art 2.2.2.05 (TomoTherapy) for helical photon IMRT, and a self-designed programme for electron IMRT.
The techniques resulted in similar mean and maximum target doses. Target coverage by the 95%-isodose was best with tomotherapy. Mean ipsilateral lung doses were similar with all techniques. Electron IMRT achieved best sparing of heart, and contralateral breast. Compared with photon IMRT, electron IMRT allowed better sparing of contralateral lung and total healthy tissue.
Electron IMRT is superior to conventional irradiation, as it allows satisfying target coverage and avoids high doses in underlying organs. Its advantage over photon IMRT is better sparing of most organs at risk (low-dose effects) which reduces the risk of radiation-induced malignancies.
常规的乳房和胸壁肿瘤照射可能会导致深部器官接受高剂量照射。光子调强放疗（IMRT）可实现靶区与治疗体积之间的高适形性，但会产生大量的低剂量效应，从而可能诱发继发性恶性肿瘤。我们比较了电子 IMRT、螺旋光子 IMRT 和常规照射的治疗计划。
使用 XiO 4.3.3（CMS）进行常规光子照射、Hi-Art 2.2.2.05（TomoTherapy）进行螺旋光子 IMRT、以及自行设计的电子 IMRT 计划，为 3 名患者（乳房、胸壁加淋巴结、胸壁/胸骨内侧肉瘤）进行治疗计划。
这些技术产生了相似的靶区平均和最大剂量。95%等剂量线覆盖靶区的效果最好的是螺旋光子 IMRT。所有技术的同侧肺平均剂量相似。电子 IMRT 对心脏和对侧乳房的保护效果最好。与光子 IMRT 相比，电子 IMRT 可更好地保护对侧肺和总健康组织。
电子 IMRT 优于常规照射，因为它可以满足靶区覆盖的要求，同时避免深部器官受到高剂量照射。与光子 IMRT 相比，电子 IMRT 的优势在于更好地保护了大多数高风险器官（低剂量效应），降低了辐射诱发恶性肿瘤的风险。
