HIGH PRESSURE XENON 3D IMAGING DETECTOR

描述(由申请人提供)：所有临床核医学成像都完全使用晶体探测器系统，这在成本和技术性能方面都施加了许多限制。在140keV的成像中，作为核医学的主力设备的NaL/PMT相机极其笨重、昂贵，并且在计数速率和空间分辨率方面都受到限制。在511keV的正电子发射计算机断层成像中，由于需要使用奇异的高Z晶体，导致成本较高且立体角度有限。密度为0.55g/cm3的氙气能产生比NaL和LSO高10倍的能量分辨率和相当于LSO的时间分辨率。在前人工作的基础上，我们提出了一种高压氙柱形脉冲电离探测器(直径20-50 mm)，其压力壳层由极低密度高强度纤维复合材料组成。通过使用这种复合材料，与容器壁的相互作用损失被降低到可以忽略的水平。此外，还提出了一种高度创新的读出技术，并对其进行了评估，其中管子内部通过有效透明的壁进行读出。初步的分析和实验研究已经证明，通用探测器元件可以实现140keV和511keV的成像，并具有1 mm量级的优异三维空间分辨率。实验研究还表明，通过利用初级相互作用过程产生的光信号和阳极处电子收集点附近的受激发射，能量分辨率接近放大器噪声极限是可能的。 因此，相对于任何室温晶体，能量分辨率都可以显著提高。所使用的氙气密度大约是NaL的六分之一，但仍然可以在合适的薄探测器上提供140keV的有效探测。对于511keV的探测，氙气中出现的多个相互作用顶点在吸收阵列中的不同管中充分展开，初级闪烁光提供1 ns的符合时间分辨率。因此，建议的探测器元件配置在适当的阵列中可以在两个主要的核医学成像领域提供极大的改进的性能。在第二阶段，将开发、建造和评估全尺寸探测器元件阵列，以预测在非常重要的SPECT和PET技术中可以实现的成像特性。

DESCRIPTION (provided by applicant):All clinical nuclear medicine imaging is done exclusively with crystal detector systems, which impose many limitations in both cost and technical performance. In 140 keV imaging, the Nal/PMT camera, the workhorse of nuclear medicine, is extremely bulky, costly, and limited in both count rate and spatial resolution. In 511 keV PET imaging, the need for exotic high Z crystals results in high cost and limited solid angle. Xenon at a density of 0.55 g/cm3 can produce a 10-fold energy resolution improvement over Nal and LSO and a time resolution comparable to LSO. Based on previous work, we propose a high pressure xenon cylindrical pulse ionization detector (20-50 mm diameter) having a pressure containing shell composed of a very low density high strength fiber composite. Through use of this composite, interaction losses with the walls of the vessel are lowered to negligible levels. Also, a highly innovative readout technique has been proposed and evaluated in which the tube interior is read out through effectively transparent walls. Pilot analytical and experimental studies have proven that a general purpose detector element can be achieved capable of both 140 keV and 511 keV imaging and having excellent 3D spatial resolution on the order of 1 mm. Experimental studies have also shown that, through use of light signals produced by both the primary interaction process and stimulated emission near the electron collection point at the anode, energy resolution approaching amplifier noise limits is possible. Thus energy resolution can be markedly improved relative to any room temperature crystal. The density of xenon employed is about 6-fold less than Nal but still affords efficient detection of 140 keV in a suitably thin detector. For 511 keV detection, the multiple interaction vertices that occur in xenon are adequately spread out among distinct tubes in an absorbing array and primary scintillation light provides coincidence time resolution of 1 ns. Thus, the proposed detector element configured in appropriate arrays can offer greatly improved performance in both of the major nuclear medicine imaging arenas. In Phase II, arrays of full sized detector elements will be developed, constructed and evaluated to predict imaging characteristics that can be achieved in very important SPECT and PET techniques.