Department of Radiation Oncology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S20-7. doi: 10.1016/j.ijrobp.2009.02.091.
We have reviewed the published data regarding radiotherapy (RT)-induced brain injury. Radiation necrosis appears a median of 1-2 years after RT; however, cognitive decline develops over many years. The incidence and severity is dose and volume dependent and can also be increased by chemotherapy, age, diabetes, and spatial factors. For fractionated RT with a fraction size of <2.5 Gy, an incidence of radiation necrosis of 5% and 10% is predicted to occur at a biologically effective dose of 120 Gy (range, 100-140) and 150 Gy (range, 140-170), respectively. For twice-daily fractionation, a steep increase in toxicity appears to occur when the biologically effective dose is >80 Gy. For large fraction sizes (>or=2.5 Gy), the incidence and severity of toxicity is unpredictable. For single fraction radiosurgery, a clear correlation has been demonstrated between the target size and the risk of adverse events. Substantial variation among different centers' reported outcomes have prevented us from making toxicity-risk predictions. Cognitive dysfunction in children is largely seen for whole brain doses of >or=18 Gy. No substantial evidence has shown that RT induces irreversible cognitive decline in adults within 4 years of RT.
我们回顾了关于放射治疗（RT）引起的脑损伤的已发表数据。放射性坏死通常在 RT 后 1-2 年出现；然而，认知功能下降则是多年发展的结果。其发生率和严重程度与剂量和体积有关，还可能因化疗、年龄、糖尿病和空间因素而增加。对于分次放疗，当生物有效剂量为 120 Gy（范围 100-140）和 150 Gy（范围 140-170）时，预计会出现 5%和 10%的放射性坏死发生率，其分次剂量大小<2.5 Gy。对于每日两次分割放疗，当生物有效剂量>80 Gy 时，毒性似乎会急剧增加。对于大的分次剂量（>或=2.5 Gy），毒性的发生率和严重程度是不可预测的。对于单次分割放射外科手术，已经证明靶区大小与不良事件的风险之间存在明确的相关性。不同中心报告的结果存在大量差异，这使得我们无法进行毒性风险预测。对于全脑剂量>或=18 Gy 的儿童，认知功能障碍是很常见的。没有确凿的证据表明 RT 在 RT 后 4 年内会导致成年人的认知功能不可逆转下降。
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