Panse Ashish S, Jain A, Wang W, Yao R, Bednarek D R, Rudin S
Medical Physics program at the University at Buffalo (SUNY). (
IEEE Nucl Sci Symp Conf Rec (1997). 2010 Oct 30;2010. doi: 10.1109/NSSMIC.2010.5874431.
We demonstrate the capability of one detector, the Micro-Angiographic Fluoroscope (MAF) detector, to image for two types of applications: nuclear medicine imaging and radiography. The MAF has 1024 × 1024 pixels with an effective pixel size of 35 microns and is capable of real-time imaging at 30 fps. It has a CCD camera coupled by a fiber-optic taper to a light image intensifier (LII) viewing a 300-micron thick CsI phosphor. The large variable gain of the LII provides quantum-limited operation with little additive instrumentation noise and enables operation in both energy-integrating (EI) and sensitive low-exposure single photon counting (SPC) modes. We used the EI mode to take a radiograph, and the SPC mode to image a custom phantom filled with 1 mCi of I-125. The phantom is made of hot rods with diameters ranging from 0.9 mm to 2.3 mm. A 1 mm diameter parallel hole, medium energy gamma camera collimator was placed between the phantom and the MAF and was moved multiple times at equal intervals in random directions to eliminate the grid pattern corresponding to the collimator septa. Data was acquired at 20 fps. Two algorithms to localize the events were used: 1) simple threshold and 2) a weighted centroid method. Although all the hot rods could be clearly identified, the image generated with the simple threshold method shows more blurring than that with the weighted centroid method. With the diffuse cluster of pixels from each single detection event localized to a single pixel, the weighted centroid method shows improved spatial resolution. A radiograph of the phantom was taken with the same MAF in EI mode without the collimator. It shows clear structural details of the rods. Compared to the radiograph, the sharpness of the emission image is limited by the collimator resolution and could be improved by optimized collimator design. This study demonstrated that the same MAF detector can be used in both radioisotope and x-ray imaging, combining the benefits of each.
我们展示了一种探测器——微型血管造影荧光镜（MAF）探测器用于两种类型应用成像的能力：核医学成像和放射成像。MAF有1024×1024像素，有效像素尺寸为35微米，能够以30帧/秒的速度进行实时成像。它有一个电荷耦合器件（CCD）相机，通过光纤锥与一个光像增强器（LII）相连，该光像增强器观察一个300微米厚的碘化铯（CsI）磷光体。LII的大可变增益提供了量子极限操作，几乎没有附加仪器噪声，并能在能量积分（EI）和灵敏的低曝光单光子计数（SPC）模式下运行。我们使用EI模式拍摄了一张射线照片，并使用SPC模式对一个填充了1毫居里碘 - 125的定制体模进行成像。该体模由直径范围从0.9毫米到2.3毫米的热棒制成。一个直径为1毫米的平行孔、中能γ相机准直器放置在体模和MAF之间，并以相等间隔在随机方向上多次移动，以消除与准直器隔片对应的网格图案。数据以20帧/秒的速度采集。使用了两种定位事件的算法：1）简单阈值法和2）加权质心法。虽然所有热棒都能清晰识别，但简单阈值法生成的图像比加权质心法生成的图像更模糊。通过将每个单个检测事件的弥散像素簇定位到单个像素，加权质心法显示出改进的空间分辨率。在没有准直器的情况下，用同一MAF在EI模式下拍摄了体模的射线照片。它显示出棒的清晰结构细节。与射线照片相比，发射图像的清晰度受准直器分辨率限制，可通过优化准直器设计来提高。这项研究表明，同一个MAF探测器可用于放射性同位素成像和X射线成像，兼具二者的优点。
