【摘要】 目的研究脑转移瘤全脑放疗中血脑屏障变化规律,为全脑放疗过程中化疗的介入时机提供影像学依据。方法对接受6MVX射线全脑外照射的20例脑转移瘤患者,在放射治疗前、放射治疗20Gy、40Gy及放射治疗结束后2周采用99mTc-DTPA核素进行脑断层显像,选择一帧显示肿瘤最好的横断层像,于肿瘤区(T)、对侧正常脑组织区(N)以及颅骨周围软组织外本底区(B)设置相同的感兴趣区,采集各区的放射性计数,分别计算放疗前、放疗20Gy、40Gy及放疗结束后2周时病灶、受到照射的正常脑组织部位的计数与本底区域计数的比值。结果放疗前20例患者其30个脑转移瘤的比值T/B和N/B分别为(142.2±51.1),(82.6±42.3);放疗20Gy时其比值分别为(260.3±121.5),(150.7±72.5);放疗40Gy时其比值分别为(251.6±118.3),(161.8±68.4);放疗结束后2周其比值分别为(250.3±117.2),(158.6±73.5)。20Gy组、40Gy组及放疗结束后2周组分别与放疗前组比较差异均有统计学意义(P<0.05),但20Gy组、40Gy组及放疗结束后2周组两两比较差异无统计学意义(P>0.05)。结论放射线具有降低血脑屏障功能的作用,照射20～40Gy及放疗结束后2周内其通透性明显增加,故20～40Gy及放疗结束后2周内均可成为化疗介入时机。更多还原

【Abstract】 Objective To study the pattern of blood-brain barrier(BBB) permeability changes during whole brain radiotherapy(WBRT) for metastatic brain tumor.Methods Twenty patients with metastatic brain tumors receiving WBRT by 6 MV X-ray underwent 99mTc-DTPA brain SPECT before and during WBRT(20,40 Gy) and at 2 weeks after the end of irradiation.A frame of transverse 99mTc-DTPA brain SPECT image that best displayed the brain metastasis was chosen,and the regions of interest(ROI) were defined in the tumor foci(T),the contralateral normal brain tissue(N) and the background outside the soft tissues around the cranium(B).The radioactive counts of every ROI were measured and the ratios of the total counts(T/B and N/B) before and during WBRT(20 Gy,40 Gy) and at 2 weeks after the irradiation were calculated.Results The average T/B and N/B in the 20 patients with 30 brain metastases was 142.2±51.1 and 82.6±42.3 before WBRT,260.3±121.5 and 150.7± 72.5 during 20 Gy WBRT,251.6±118.3 and 161.8±68.4 during 40 Gy WBRT,and 250.3±117.2 and 158.6±73.5 at 2 weeks after the irradiation,respectively.The measurements during WBRT(20 and 40 Gy) and at 2 weeks after the irradiation group underwent no significant variations(P>0.05),but showed significant differences from those before WBRT(P<0.05).Conclusion Irradiation causes direct damage of the BBB function,and the permeability of the BBB increases significantly during and within 2 weeks following 20 and 40 Gy WBRT,which provides the optimal time window for interventions with chemotherapy.更多还原