New knowledge about the bremsstrahlung image of strontium-89 with the scintillation camera
New knowledge about the bremsstrahlung image of strontium-89 with the scintillation camera
复制标题
关于使用闪烁相机拍摄的锶89轫致辐射图像的新认识
DOI：
10.1007/s12149-012-0615-2
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发表时间：
2012
影响因子：
2.6
通讯作者：
M. Fukushi
中科院分区：
文献类型：
--
作者：
H. Narita;K. Hirase;M. Uchiyama;M. Fukushi
目的应用~(89)锶氯化锶治疗骨转移瘤。1996年，发明了一种用闪烁相机观察89锶氯化物分布的方法。使用韧致辐射成像的研究表明，89Sr在骨骼中积累，从骨骼周围的生物组织产生的韧致辐射不超过30千电子伏特。然而，目前尚不清楚来自骨骼的低能量韧致辐射如何产生约75千电子伏特的峰值能级。方法用闪烁相机测量了89Sr源的能谱，并与中低能量通用准直器进行了比较。4个窗口的能量窗设置为20-650keV。在闪烁相机和89Sr源之间放置了一块50毫米厚的丙烯酸块，以排除韧致辐射的影响。在无准直器的情况下，用闪烁相机获得了覆盖有铅的89Sr的能谱。结果在有准直器的情况下，能谱曲线与没有50 mm亚克力的能谱曲线相似。能谱曲线显示了约75、170和520keV的峰值。在没有准直器的情况下，能谱显示出类似的曲线，但在75keV的峰值没有峰值。该曲线与闪烁相机和准直器测得的曲线相似，但当89Sr源被放置在铅容器中时，得到的曲线与没有屏蔽源且准直器没有安装在闪烁相机上时得到的曲线相似。结论如果89Sr的韧致辐射产生图像，则在89Sr源和闪烁相机之间放置丙烯时，低能谱区应该减少。然而，无论是加入丙烯酸酯还是不加入丙烯酸酯，都得到了相似的曲线。因此，我们认为闪烁相机探测到的辐射不是韧致辐射，这是由于89Sr的β射线造成的。大多数~(89)锶制剂受到~(85)Sr的污染，~(85)Sr的大部分伽马射线能量为514千电子伏特。闪烁相机通过与85Sr的伽马射线相互作用，从准直器材料(铅和其他物质)中探测到约75keV的特征X射线能量。
ObjectiveStrontium-89 (89Sr) chloride has been used to treat metastases in bone. A method to visualize the distribution of89Sr chloride with a scintillation camera was developed in 1996. Studies using bremsstrahlung imaging have shown that89Sr accumulates in bone and that the bremsstrahlung generated from biological tissue surrounding bone does not exceed 30 keV. However, it was not clear how low-energy bremsstrahlung from bone can produce peak energy levels of around 75 keV. We speculate that a different (unidentified) factor is involved.MethodsThe energy spectrum of an89Sr source was acquired with a scintillation camera with or without a low-to-medium-energy general-purpose collimator. The energy window was set at 20–650 keV for 4 windows. A 50-mm thick acrylic block was placed between the scintillation camera and the89Sr source to exclude the effects of bremsstrahlung. The energy spectrum of89Sr covered with lead was acquired using the scintillation camera without a collimator.ResultsWith the collimator the energy spectrum curve was similar to that without the 50 mm of acrylic. The energy spectrum curve showed peaks at about 75, 170, and 520 keV. Without the collimator the energy spectrum showed a similar curve but no peak at 75 keV peak. The curve was similar to that obtained with the scintillation camera and the collimator; however, the curve obtained when the89Sr source had been placed in a lead container was similar to that obtained when the source was unshielded, and the collimator was not attached to the scintillation camera.ConclusionIf bremsstrahlung of89Sr produces an image, a low-energy spectrum region should decrease when acrylic is placed between the89Sr source and the scintillation camera. However, similar curves were obtained both with the acrylic in place and without the acrylic. Therefore, we believe that the radiation detected by the scintillation camera was not bremsstrahlung due to the beta rays of89Sr. Most89Sr preparations are contaminated by85Sr, and most of the gamma ray energy of85Sr is 514 keV. The scintillation camera detected the characteristic X-ray energy of about 75 keV from the materials of the collimator (lead and others) through interaction with the gamma rays of85Sr.