Active energy selective image detector for dual-energy computed radiography.
Active energy selective image detector for dual-energy computed radiography.
复制标题
用于双能计算机放射线照相的主动能量选择性图像探测器。
DOI：
10.1118/1.597831
复制
发表时间：
1996
期刊：
影响因子：
3.8
通讯作者：
Alvarez,RE
中科院分区：
文献类型：
--
作者：
Alvarez,RE
已开发出一种用于双能量计算机X射线摄影的新能量选择性探测器，该探测器结合了X射线管电压切换和单次曝光双屏探测器的许多优点。新的有源探测器利用存储荧光屏响应的电光调制，允许在屏幕不移动的情况下进行双曝光采集。电光调制可以快速完成，因此探测器可以在足够短的时间内采集电压切换图像，以最大限度地减少患者运动伪影。电压切换产生有效的检测能量谱，对于给定的患者剂量，其导致比双屏检测器的有效谱低得多的噪声。本文介绍了这一新概念，通过计算机模拟确定了最佳电压和滤波器材料，并将有源探测器的性能与其他能量选择探测器进行了比较。与双屏探测器相比，新探测器在相同剂量下的信噪比平方（SNR 2）提高了30倍以上，在相同X射线管负载下的SNR 2提高了5倍以上。定量确定X射线暴露不完全擦除的影响。通过可实现的擦除分数，SNR 2在相同剂量下比双屏检测器好20倍以上，在恒定管负载下比双屏检测器好3倍以上。主动式检测器还与机械屏幕切换进行了比较。对于相同的剂量，机械开关提供了更好的SNR 2，大约是最佳X射线管电压下有源探测器SNR 2的1.1倍。性能与高吸收背屏幕进行比较。如果在有源和无源探测器两者中使用这些，则两个探测器的品质因数都增加，但是有源探测器相对于无源探测器的优势随着大的背屏厚度而降低。
A new energy selective detector for dual energy computed radiography has been developed that combines many of the advantages of x‐ray tube voltage switching and single exposure double screen detectors. The new active detector utilizes electro‐optical modulation of the response of the storage phosphor screens to allow dual exposure acquisition with no motion of the screens. Electro‐optical modulation can be done rapidly so the detector can acquire the voltage switched images in a short enough time to minimize patient motion artifacts. Voltage switching produces effective detected energy spectra that result in much lower noise for a given patient dose than the effective spectra of double screen detectors. In this paper the new concept is described, optimal voltages and filter materials are determined by computer simulations, and the active detector performance is compared to other energy selective detectors. The new detector provides over 30 times better signal to noise ratio squared (SNR2) for the same dose and over five times better SNR2for the same x‐ray tube loading than a double screen detector. The effects of incomplete erasure of the x‐ray exposures are determined quantitatively. With achievable erasing fractions, the SNR2is over 20 times better for the same dose and over three times better for constant tube loading than a double screen detector. The active detector is also compared to mechanical screen switching. Mechanical switching provides somewhat better SNR2for the same dose, approximately 1.1 times the active detector SNR2at optimal x‐ray tube voltages. The performance is compared with highly absorbing back screens. If these are used in both the active and passive detectors, both detectors' quality factors increase, but the advantage of the active detector over the passive detector decreases with large back screen thicknesses.