Novel photon-counting low-dose computed tomography using a multi-pixel photon counter
Novel photon-counting low-dose computed tomography using a multi-pixel photon counter
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DOI：
10.1016/j.nima.2017.02.015
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发表时间：
2017-02
影响因子：
1.4
通讯作者：
Hayato Morita;Tsubasa Oshima;J. Kataoka;M. Arimoto;Hideo Nitta
中科院分区：
文献类型：
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作者：
Hayato Morita;Tsubasa Oshima;J. Kataoka;M. Arimoto;Hideo Nitta
X 射线计算机断层扫描 (CT) 广泛应用于诊断成像。由于与该方法相关的强辐射暴露，已经提出了许多减少辐射剂量的建议。此外，传统 CT 无法提供与每个 X 射线光子相关的能量信息，因为强度相当高，通常达到 10 7− 9 cps/mm 2 。在这里，我们提出了一种基于多像素光子计数器（MPPC）和高速闪烁体的新型低剂量光子计数 CT 系统。为了证明利用 MPPC 的内部增益和快速时间响应的高信噪比，我们比较了光电二极管 (PD)、雪崩光电二极管和 MPPC 在相同条件下获取的 CT 图像。特别是，与使用 PD 的传统 CT 获取的图像相比，使用 MPPC 获取的图像的对比度噪声比 (CNR) 提高了 12.6 倍。我们还采用20、40、60和80 keV 4个能量阈值进行能量分辨成像。我们证实 CT 图像的成像对比度得到了显着改善，并且束硬化也有所减少。我们的结论是，所提出的基于 MPPC 的探测器很可能是未来 CT 扫描仪中使用的有前途的设备。
X-ray computed tomography (CT) is widely used in diagnostic imaging. Owing to a strong radiation exposure associated with this method, numerous proposals have been made for reducing the radiation dose. In addition, conventional CT does not provide information on the energy associated with each X-ray photon because intensity is rather high, typically amounts to 10 7− 9 cps/mm 2. Here, we propose a novel, low-dose photon-counting CT system based on a multi-pixel photon counter (MPPC) and a high-speed scintillator. To demonstrate high signal-to-noise ratio utilizing the internal gain and the fast time response of the MPPC, we compared CT images acquired under the same conditions among a photodiode (PD), an avalanche photodiode and a MPPC. In particular, the images' contrast-to-noise ratio (CNR) acquired using the MPPC improved 12.6-fold compared with the images acquired in conventional CT using a PD. We also performed energy-resolved imaging by adopting 4 energy thresholds of 20, 40, 60, and 80 keV. We confirmed a substantial improvement of the imaging contrast as well as a reduction in the beam hardening for the CT images. We conclude that the proposed MPPC-based detector is likely to be a promising device for use in future CT scanners.