功能神经外科的选择:OUR-XGD旋转式伽玛刀放射生物学效应

背景伽玛刀是立体定向放射外科的有效手段之一,为使靶区之外的健康组织损伤最小,对照射剂量和准直器大小的选择很有必要. 目的验证国产 OUR XGD旋转式伽玛刀的安全性和准确性 ,探讨其放射生物学效应. 设计完全随机设计. 地点和对象实验地点解放军海军总医院澳海伽玛刀立体定向放射治疗研究中心.选用健康家犬 10只,按准直器大小的不同随机分为 3组.干预对右额脑实质进行旋转式伽玛刀不同剂量照射,直径 4 mm组 90 Gy 2只, 120 Gy 2只, 150 Gy 2只, 180 Gy 2只;直径 8 mm组 120 Gy 1只;直径 14 mm组 100 Gy 1只.观察其不同准直器、不同剂量、不同时间的放射生物学效应. 主要观察指标照射后定期观察动物行为学、 MR影像学及不同时间的病理学变化. 结果不同大小准直器和不同剂量照射后于不同时间内在 MR影像上出现坏死病灶,直径 4 mm 120 Gy、直径 4 mm 150 Gy和直径 14 mm 100 Gy组于照射后 3个月出现毁损病灶( 7.5 mm× 7.5 mm× 8.0 mm,8.0 mm × 8.0 mm× 9.0 mm,33.0 mm× 32.0 mm× 34.0 mm),而直径 4 mm 180 Gy和直径 8 mm 120 Gy组于照射后 1个月显示毁损病灶出现.病理学证实坏死灶边缘较清晰锐利,周围一定范围内的脑组织有不同程度水肿改变. 结论 OUR XGD旋转式伽玛刀具有良好的安全性、准确性和放射生物学效应;伽玛刀照射后组织的损伤反应程度与准直器的大小有着明显的关系,并存在明显的剂量时间曲线关系;为功能性神经外科疾病的治疗剂量选择提供了理论依据.

Choice of functional neurosurgery:radiobiological effects of OUR-XGD rotating gamma knife

BACKGROUND:Gamma knife is one of the effective approaches in Stereotactic Radiosurgery.It is very necessary to select the radiation dose and collimator size for minimizing the damage to healthy tissues outside the target areas. OBJECTIVE:To validate the safety and accuracy of OUR-XGD Rotating Gamma Knife as well as its radiobiological effects. DESIGN: A randomized controlled trial. SETTING and PARTICIPANTS:The study was conducted in the Auhai Gamma Knife Stereotactic Radiotherapy Center of the General Navy Hospital of PLA.10 healthy canines were selected and randomly allocated into 3 groups according to the size of the collimator. INTERVENTIONS:The brain tissues of right frontal lobe were radiated by OUR-XGD Rotating Gamma Knife with different radiation doses.4 mm-diameter group: 90 Gy× 2 canines,120 Gy× 2 canines,150 Gy × 2 canines, and 180 Gy× 2 canines; 8 mm- diameter group: 120 Gy× 1 canine,and 14mm-diameter group:100 Gy× 1 canine.The radiobiological effects at different time with different dose and different size of the collimator were observed. MAIN OUTCOME MEASURES:The behaviors of the animals,MRI and the pathological changes over time were observed periodically after radiation. RESULTS:The necrotic lesions were appeared on MRI at different time with different size of collimator and different radiation dose.Necrotic lesions appeared at 3 months after radiation in groups of 4 mm-diameter 120 Gy,4 mm-diameter 150 Gy and 14 mm-diameter 100 Gy(7.5 mm× 7.5 mm × 8.0 mm,8.0 mm× 8.0 mm× 9.0 mm,and 33.0 mm× 32.0 mm× 34.0 mm respectively),while the necrotic lesions appeared at 1 month after radiation in groups of 4 mm-diameter 180 Gy and 8 mm-diameter 120 Gy.The pathological examination proved that the coagulated necrotic lesions had relative clear and sharp zone and edema was found in the brain tissue around the necrotic lesions in certain range as well. CONCLUSION:OUR-XGD Rotating Gamma Knife has favorable safety,accuracy and radiobiological effects.The extent of tissue injury after radiation by Gamma knife significantly relates with the size of collimator,and moreover,a dosage-dependent relationship obviously exists,which provides an experimental basis for the dose selection in the treatment of functional neurosurgical diseases.