Section of Head, Neck, Lung and Skin tumours, Department of Cancer, Karolinska University Hospital, Stockholm, Sweden.
Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden.
J Radiol Prot. 2021 Nov 3;41(4). doi: 10.1088/1361-6498/ac28ef.
The bronchial tolerance to high doses of radiation is not fully understood. However, in the event of a radiological accident with unintended exposure of the central airways to high doses of radiation it would be important to be able to anticipate the clinical consequences given the magnitude of the absorbed dose to different parts of the bronchial tree. Stereotactic body radiation therapy (SBRT) is a radiation treatment technique involving a few large fractions of photon external-beam radiation delivered to a well-defined target in the body. Despite generally favourable results, with high local tumour control and low-toxicity profile, its utility for tumours located close to central thoracic structures has been questioned, considering reports of severe toxic symptoms such as haemoptysis (bleedings from the airways), bronchial necrosis, bronchial stenosis, fistulas and pneumonitis. In conjunction with patient- and tumour-related risk factors, recent studies have analysed the absorbed radiation dose to different thoracic structures of normal tissue to better understand their tolerance to these high doses per fraction. Although the specific mechanisms behind the toxicity are still partly unknown, dose to the proximal bronchial tree has been shown to correlate with high-grade radiation side effects. Still, there is no clear consensus on the tolerance dose of the different bronchial structures. Recent data indicate that a too high dose to a main bronchus may result in more severe clinical side effects as compared to a smaller sized bronchus. This review analyses the current knowledge on the clinical consequences of bronchial exposure to high dose hypofractionated radiation delivered with the SBRT technique, and the tolerance doses of the bronchi. It presents the current literature regarding types of high-grade clinical side effects, data on dose response and comments on other risk factors for high-grade toxic effects.
高剂量辐射的支气管耐受性尚不完全清楚。然而，在放射性事故中，中央气道意外暴露于高剂量辐射下，能够预测不同支气管部位吸收剂量的临床后果将非常重要。立体定向体部放射治疗（SBRT）是一种放射治疗技术，涉及身体内的靶区给予几大分次的光子外照射。尽管一般结果良好，局部肿瘤控制率高且毒性低，但由于靠近中央胸部结构的肿瘤的严重毒性症状（如咯血、支气管坏死、支气管狭窄、瘘管和肺炎）的报道，其应用受到质疑。结合患者和肿瘤相关的危险因素，最近的研究分析了不同胸部结构的正常组织吸收的辐射剂量，以更好地了解它们对这些高剂量/分次的耐受性。尽管毒性的具体机制尚不完全清楚，但近端支气管树的剂量已被证明与高级别放射性副作用相关。尽管如此，不同支气管结构的耐受剂量仍没有明确的共识。最近的数据表明，主支气管的剂量过高可能导致比小支气管更严重的临床副作用。这篇综述分析了 SBRT 技术下接受高剂量少分次辐射暴露的支气管的临床后果以及支气管的耐受剂量的现有知识。它介绍了关于高级别临床副作用类型、剂量反应的数据以及对高级别毒性作用的其他危险因素的评论。
