Development of a low-sensitivity high resolution YAP(Ce) scintillation camera system toward the real-time imaging of an 192Ir source during high-dose-rate brachytherapy
Development of a low-sensitivity high resolution YAP(Ce) scintillation camera system toward the real-time imaging of an 192Ir source during high-dose-rate brachytherapy
复制标题
开发低灵敏度高分辨率 YAP(Ce) 闪烁摄像系统，用于高剂量率近距离放射治疗期间 192Ir 源的实时成像
DOI：
10.1088/1748-0221/15/12/p12018
复制
发表时间：
2020
影响因子：
1.3
通讯作者：
Yoshikawa A.
中科院分区：
文献类型：
--
作者：
Nagata J.;Yamamoto S.;Noguchi Y.;Nakaya T.;Okudaira K.;Kamada K.;Yoshikawa A.
在高剂量率(HDR)近距离治疗中，需要测量高活度Ir-192(192Ir)源的精确位置，以检测源的错误定位并避免事故发生。虽然使用高能伽马相机实时成像源位置是一种可能的方法，但由于192Ir源的活度如此之高，电子设备在离源很小的距离处就饱和了。为了解决这一问题，我们开发了一种低灵敏度高分辨率伽马相机。为了降低灵敏度，我们使用了1 mm厚的掺铈钙钛矿(YAl_2O_3：YAP(Ce))闪烁体。开发的低灵敏度伽马相机由这种薄的YAP(Ce)闪烁体光学耦合到平板光电倍增管(FP-PMT)组成。它被包裹在一个20毫米厚的钨屏蔽体中，头部安装了一个直径0.5毫米的针孔准直器。在距192 Ir源100 mm处的空间分辨率为3.3 mm，灵敏度为0.52cps/mBq。该相机的计数速率为∼180kcps，距离212.4-GBq192Ir源100 mm，可以对192Ir源进行实时成像。在伽马相机和192 Ir源之间放置一个100 mm厚的水模，我们将计数率降低了一半，但可以清晰地观察到192 Ir源图像。我们认为，研制的低灵敏度高分辨率伽马相机系统有可能成为一种新型的HDR近距离放射治疗实时成像系统。
Measurement of the precise position of a high activity iridium-192 (192 Ir) source during high-dose-rate (HDR) brachytherapy is desired to detect the mispositioning of the source and avoid incidents. Although real-time imaging of the source position using a high-energy gamma camera is a possible method for this purpose, electronics are saturated at small distances from the source because the 192 Ir source activity is so high. To solve this problem, we developed a low-sensitivity high-resolution gamma camera. We used a 1-mm-thick cerium-doped yttrium aluminum perovskite (YA1O 3: YAP (Ce)) scintillator plate to reduce sensitivity. The developed low-sensitivity gamma camera consists of this thin YAP (Ce) scintillator optically coupled to a flat panel photomultiplier tube (FP-PMT). It is encased in a 20-mm-thick tungsten shield with a 0.5-mm diameter pinhole collimator mounted on its head. The spatial resolution of the gamma camera at 100 mm from the 192 Ir source was 3.3 mm FWHM and the sensitivity was 0.52 cps/MBq. The count rate of the camera was∼ 180-k cps at 100 mm from the 212.4-GBq 192 Ir source and real-time imaging of the 192 Ir source was possible. With a 100-mm-thick water phantom positioned between the gamma camera and the 192 Ir source, we decreased the count rate to half, but the 192 Ir source images could be observed clearly. We conclude that the developed low-sensitivity high-resolution gamma camera system has the potential to be a new real-time imaging system for HDR brachytherapy.