The quantitative accuracy and image quality of multi-isotope SPECT is affected by various hardware-related perturbations. The present study evaluates the simultaneous acquisition of multiple isotopes using a multiplexed multi-pinhole SPECT system, assesses the extent of different error sources, and proposes experimental procedures for its objective characterization. Methods: Phantom measurements with single-, dual- and triple-isotope combinations of 99mTc, 111In, 123I, 177Lu, and 201Tl were performed with the NanoSPECT/CTPLUS to evaluate system energy resolution, count rate performance, sensitivity, collimator penetration, hardware versus object scatter, spectral crosstalk, spatial resolution, spatial registration accuracy, image uniformity, image noise, and image quality. Results: The intrinsic detector properties were suitable for the simultaneous acquisition of up to 3 isotopes with limitations for count rates exceeding 104 kcps and γ-energies lower than 75 keV. Spectral crosstalk between isotopes was more likely mediated by hardware than by source scatter and was strongly dependent on the isotope combination. Simultaneous multi-isotope acquisitions slightly degraded spatial resolution and image uniformity for spatially superimposed but not for spatially separated activity distributions while the background noise level was increased for all multi-isotope studies. For particular isotopes, collimator penetration and x-ray fluorescence contributed a significant portion of error. Conclusion: The NanoSPECT/CTPLUS enables the simultaneous acquisition of 3 radioisotopes with high quantitative accuracy and only little loss of image quality when the activity ratio is adapted to isotope-specific count rate sensitivities and when the system calibration is performed with phantoms of appropriate size.

中文翻译：

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小动物多针孔SPECT系统的多同位素功能。

多同位素SPECT的定量精度和图像质量受各种与硬件相关的干扰的影响。本研究评估使用多重多针孔SPECT系统同时采集多个同位素，评估不同误差源的程度，并提出用于其客观表征的实验程序。方法：使用NanoSPECT / CTPLUS用99mTc，111In，123I，177Lu和201Tl的单同位素，双同位素和三同位素组合进行幻像测量，以评估系统能量分辨率，计数率性能，灵敏度，准直仪穿透力，硬件与物体散射，光谱串扰，空间分辨率，空间配准精度，图像均匀性，图像噪声和图像质量。结果：固有的检测器特性适合同时捕获多达3种同位素，但其计数率超过104 kcps，γ能量低于75 keV时受到限制。同位素之间的光谱串扰更可能是由硬件而不是由源散射来介导，并且很大程度上取决于同位素的组合。对于所有多同位素研究，同时多同位素采集对于空间叠加略微降低了空间分辨率和图像均匀性，但对于空间分离的活动分布却没有，而背景噪声水平却有所提高。对于特定的同位素，准直仪的穿透力和X射线荧光造成了很大一部分误差。结论：