Brenner David J, Hall Eric J
Center for Radiological Research, Columbia University Medical Center, NY 10032, USA.
Radiother Oncol. 2008 Feb;86(2):165-70. doi: 10.1016/j.radonc.2007.12.003. Epub 2008 Jan 14.
Hospital-based proton facilities may represent a major advance in radiation therapy, in part because of excellent dose distributions around the tumor, and in part because of the potentially lower whole-body dose compared with photon radiotherapy. Most current proton beams are spread out to cover the tumor using beam scattering and collimation techniques (passive scattering); this will necessarily result in an extra whole-body neutron dose, due to interactions of the protons with the scattering and collimating beam elements. However, the clinical significance of this whole-body low-dose neutron exposure has remained controversial. The number of proton facilities worldwide is increasing rapidly, and most of these facilities are/will be based on passive scattering. Thus it is important to assess and, ideally, minimize, the potential for second cancer induction by secondary neutrons. We discuss here the neutron doses involved, and the associated potential second cancer risks, with an emphasis on the uncertainties involved.
基于医院的质子治疗设施可能代表着放射治疗的一项重大进展，部分原因是肿瘤周围具有出色的剂量分布，部分原因是与光子放射治疗相比，全身剂量可能更低。目前大多数质子束通过束流散射和准直技术（被动散射）散开以覆盖肿瘤；由于质子与散射和准直束流元件的相互作用，这必然会导致额外的全身中子剂量。然而，这种全身低剂量中子照射的临床意义一直存在争议。全球范围内质子治疗设施的数量正在迅速增加，其中大多数设施是/将基于被动散射。因此，评估并理想情况下尽量减少次级中子诱发二次癌症的可能性非常重要。我们在此讨论所涉及的中子剂量以及相关的潜在二次癌症风险，重点是其中涉及的不确定性。
