2012年10月28-31日，第54届美国放射肿瘤学会（ASTRO）年会在美国波士顿举行。来自世界各地的放射肿瘤学领域的医生及相关人士共计11000多人参会。本届年会的主题是“通过创新改善患者治疗（Advancing Patient Care through Innovation）”。 对本届年会进行了专题报道（http://zt.cmt.com.cn/zt/astro2012/index.html），敬请关注！

　　会上，美国学者报告了一项研究：The Role of Proton Radiation Therapy for Multiple Meningiomas ，其摘要如下：

Purpose/Objective(s)
To compare the dose delivered by proton radiation therapy to the dose delivered by intensity modulated radiation therapy (IMRT) for patients presenting with multiple intracranial meningiomas.

Materials/Methods
We compared proton radiation therapy and non-coplanar IMRT plans for 4 patients who presented with multiple simultaneous meningiomas. We required that each plan deliver the prescription dose (50.4 Gy at 1.8 Gy per fraction for WHO Grade I meningiomas and 61.2 Gy at 1.8 Gy per fraction for WHO Grade II meningiomas) to 95% of the planning target volume. We compared the dose to 0.1 cc of the critical normal tissue structures (brainstem, optic nerves, and optic chiasm), the mean dose to the brain, the V50, V20, and V30 of the brain, and the integral dose received by each patient.

Results
The normal-tissue dose constraints were met for each structure using either IMRT or proton radiation therapy. With the IMRT plans, the integral dose received by each of the 4 patients was 62.3 J, 94.5 J, 66.2 J, and 40.2 J. The integral dose with the proton plan was significantly reduced; the integral dose for each patient was 22.4 J, 26.6 J, 22.1 J, and 16.2 J. The mean dose to the brain delivered by the IMRT plans for each of the 4 patients was 26.92 Gy, 32.71 Gy, 17.58 Gy, and 18.75 Gy. The mean dose delivered to the brain using the proton plans for each of the 4 patients was 12.76 Gy, 8.96 Gy, 11.64 Gy, and 8.92 Gy. In addition, the V20, V30, and V50 of the brain were either the same or better when comparing the proton plans to the IMRT plans.

Conclusions
Compared to IMRT, proton radiation therapy allows for a significantly lower dose to the brain and optic structures when treating multiple brain lesions because of the proton's Bragg peak. More specifically, with proton therapy, the integral dose to the brain and optic structures is reduced as is the mean dose to the brain, allowing for fewer toxicities and the safer treatment of patients with multiple meningiomas.