Iodine-131 imaging using 284 keV photons with a small animal CZT-SPECT system dedicated to low-medium-energy photon detection.
Iodine-131 imaging using 284 keV photons with a small animal CZT-SPECT system dedicated to low-medium-energy photon detection.
复制标题
使用 284 keV 光子和专用于中低能光子检测的小动物 CZT-SPECT 系统进行 Iodine-131 成像。
DOI：
10.1007/s12149-015-1028-9
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Okada S.
中科院分区：
文献类型：
--
作者：
Kojima A;Gotoh K;Shimamoto M;Hasegawa K;Okada S.
碘-131因其β粒子而广泛用于放射性核素治疗，并用于使用其主要伽马射线的诊断成像。由于该主伽马射线具有364 keV的相对高的能量，因此可能需要小动物单光子发射计算机断层摄影（SPECT）成像系统具有对这种较高能量的光子进行成像的能力。本研究的目的是研究在小动物SPECT成像系统中使用其284 keV光子而不是其364 keV光子对I-131进行成像的可能性，该系统专用于检测中低能量光子方法所用的成像系统是具有CZT探测器的市售临床前SPECT仪器，其配备有多个CZT探测器。针孔准直器，并伴随着CT成像仪。用于I-131成像的能量窗口被设置为284 keV的峰值，与364 keV光子相比具有低丰度。扫描了小型线源和两只注射NaI-131的小鼠（两种类型各一只）。结果尽管由于364 keV光子穿透准直器，重建图像的外围区域出现了较高的计数，但小型线源的形状可以很好地可视化。测得的空间分辨率相对较差（半峰全宽约为1.9 mm，第10峰全宽约为3.9 mm）。然而，观察到SPECT值和I-131放射性水平之间具有良好的线性相关性。此外，委员会认为，在与X射线CT图像融合的3D-SPECT图像中清楚地识别了两只小鼠甲状腺对NaI-131的摄取。无法使用364 keV光子采集图像的SPECT系统。
ObjectiveIodine-131 is widely used for radionuclide therapy because of its β-particle and for diagnostic imaging employing its principal gamma ray. Since that principal gamma ray has the relatively high energy of 364 keV, small animal single-photon emission computed tomography (SPECT) imaging systems may be required to possess the ability to image such higher energy photons. The aim of this study was to investigate the possibility of imaging I-131 using its 284 keV photons instead of its 364 keV photons in a small animal SPECT imaging system dedicated to the detection of low-medium-energy photons (below 300 keV).MethodsThe imaging system used was a commercially available preclinical SPECT instrument with CZT detectors that was equipped with multi-pinhole collimators and was accompanied by a CT imager. An energy window for I-131 imaging was set to a photopeak of 284 keV with a low abundance compared with 364 keV photons. Small line sources and two mice, one of each of two types, that were injected with NaI-131 were scanned.ResultsAlthough higher counts occurred at the peripheral region of the reconstructed images due to the collimator penetration by the 364 keV photons, the shape of the small line sources could be well visualized. The measured spatial resolution was relatively poor (~1.9 mm for full width at half maximum and ~3.9 mm for full width at tenth maximum). However, a good linear correlation between SPECT values and the level of I-131 radioactivity was observed. Furthermore, the uptake of NaI-131 to the thyroid gland for the two mice was clearly identified in the 3D-SPECT image fused with the X-ray CT image.ConclusionWe conclude that the use of an energy window set on the photopeak of 284 keV and the multi-pinhole collimator may permit I-131 imaging for a preclinical CZT-SPECT system that does not have the ability to acquire images using the 364 keV photons.