McDonald B S, Shokouhi S, Barrett H H, Peterson T E
Department of Physics & Astronomy, Vanderbilt University, 1807 Station B Nashville, TN 37235, USA.
Nucl Instrum Methods Phys Res A. 2007 Aug 21;579(1):196-199. doi: 10.1016/j.nima.2007.04.142.
We investigated a scheme for concurrently detecting low- and high-energy emissions from (123)I with a stacked silicon double-sided strip detector (DSSD) and modular scintillation camera (Modcam) from the FastSPECT II design. We sequentially acquired both low- and high-energy emission images of an (123)I object with a prototype DSSD and a Modcam. A sandwich aperture increases spatial resolution in the low-magnification DSSD image via a smaller pinhole diameter and allows a higher magnification image on the Modcam. Molybdenum, the insert material, efficiently stops 20-30 keV photons due to its ∼20 keV K-edge. Theoretically, less than 10% of 159 keV photons interact in 0.035 cm thick sheet of molybdenum, while this thickness stops virtually all ∼30 keV photons. Thus, photons from both energy regions will be incident upon their respective detectors with little cross talk. With a multi-pinhole collimator, we can decode multiplexed images on the Modcam by making use of the lower-magnification DSSD image. This approach can provide an increase in system sensitivity compared to single-detector configurations. Using MCNP5 we examined the potential benefits and drawbacks of stacked detectors and the sandwich aperture for small-animal pinhole SPECT via the synthetic-collimator method. Simulation results encourage us to construct the novel aperture and use it with our new DSSDs designed for mounting in a transmission configuration.
我们研究了一种方案，该方案使用来自FastSPECT II设计的堆叠式硅双面条探测器（DSSD）和模块化闪烁相机（Modcam）同时检测¹²³I的低能和高能发射。我们使用原型DSSD和Modcam依次获取了¹²³I物体的低能和高能发射图像。夹心孔径通过较小的针孔直径提高了低倍率DSSD图像的空间分辨率，并允许在Modcam上获得更高倍率的图像。插入材料钼由于其约20 keV的K边，能有效地阻挡20 - 30 keV的光子。理论上，在0.035 cm厚的钼片中，159 keV光子的相互作用不到10%，而这个厚度几乎能阻挡所有约30 keV的光子。因此，来自两个能量区域的光子将以很少的串扰入射到各自的探测器上。使用多孔径准直器，我们可以通过利用低倍率DSSD图像来解码Modcam上的多路复用图像。与单探测器配置相比，这种方法可以提高系统灵敏度。我们使用MCNP5通过合成准直器方法研究了堆叠探测器和夹心孔径在小动物针孔SPECT中的潜在优缺点。模拟结果促使我们构建这种新型孔径，并将其与设计用于透射配置的新型DSSD一起使用。
