Drost D J, Fenster A
Med Phys. 1984 Sep-Oct;11(5):602-9. doi: 10.1118/1.595621.
We have designed, constructed, and tested a 95-channel prototype xenon ionization detector for use in scanned projection radiography (SPR). This detector has higher spatial resolution, is more dose efficient, and is easier to construct than computed tomography (CT) xenon ionization detectors. It consists of two parallel plates separated by a 2-mm gap filled with xenon gas at 2 MPa (20 atm). One plate is a high-voltage electrode while the other is a circuit board etched to form an array of metal collector strips focused on the x-ray source. The resulting detector channels are 0.5 mm wide and 6 cm long. In this paper we present results from measurements of system noise and detector channel calibration. We compared the detector system to a screen/film system and found that it allows the detection of structures with 0.17% radiographic contrast compared to 2% contrast required for detection with screen/film when tested by imaging a 10-cm-thick Lucite phantom with a 10 X 10(-6) C/kg exposure. From images of resolution test patterns, the limiting resolution of the detector is 2.0 1p/mm at 1.6 magnification. Images of reduction mammoplasty tissue samples, obtained with 1/17 the exposure of screen/film images, had the same low-contrast sensitivity but contained less high-contrast detail than the film images.
我们设计、制造并测试了一种用于扫描投影放射成像（SPR）的95通道氙气电离探测器原型。该探测器具有更高的空间分辨率、更高的剂量效率，并且比计算机断层扫描（CT）氙气电离探测器更易于制造。它由两块平行板组成，中间有一个2毫米的间隙，填充着2兆帕（20个大气压）的氙气。一块板是高压电极，另一块是蚀刻成金属收集条阵列的电路板，这些收集条聚焦于X射线源。由此产生的探测器通道宽0.5毫米，长6厘米。在本文中，我们展示了系统噪声测量和探测器通道校准的结果。我们将探测器系统与屏/片系统进行了比较，发现在用10×10⁻⁶库仑/千克的曝光量对10厘米厚的有机玻璃模型进行成像测试时，它能够检测出对比度为0.17%的结构，而屏/片系统检测需要2%的对比度。从分辨率测试图案的图像来看，探测器在1.6倍放大率下的极限分辨率为2.0线对/毫米。用相当于屏/片图像1/17的曝光量获得的缩乳术组织样本图像，具有相同的低对比度敏感度，但与胶片图像相比，高对比度细节较少。
