Stenvall Anna, Ceric Andelius Irma, Nilsson Elias, Lindvall Albin, Larsson Erik, Gustafsson Johan
Radiation Physics, Department of Haematology, Oncology, and Radiation Physics, Skåne University Hospital, Lund, Sweden.
Department of Translational Medicine and Wallenberg Centre of Molecular Medicine, Lund University, Malmö, Sweden.
EJNMMI Phys. 2024 Nov 4;11(1):91. doi: 10.1186/s40658-024-00693-5.
The aim was to compare bias and precision for Lu-SPECT activity-concentration estimation using a dual-headed Anger SPECT system and a ring-configured CZT SPECT system. This was investigated for imaging at 208 keV and 113 keV, respectively.
Phantom experiments were performed on a GE Discovery 670 system with 5/8'' NaI(Tl) crystal (dual-headed Anger system) and a GE StarGuide (ring-configured CZT system). Six spheres (1.2 mL to 113 mL) in a NEMA PET body phantom were filled with Tc and Lu, separately. Mean relative errors and coefficients of variation (CV) in estimated sphere activity concentration were studied over six timeframes of 10 min each for the two systems. For Lu, similar acquisitions were also performed for an anthropomorphic phantom with two spheres (10 mL and 25 mL) in a liver with non-radioactive background and a sphere-to-background ratio of 15:1. Tomographic reconstruction was performed using OS-EM with 10 subsets with compensation for attenuation, scatter, and distance-dependent spatial resolution. For the Anger system, up to 40 iterations were used and for the ring-configured CZT system up to 30 iterations were used.
The two systems showed similar mean relative errors and CVs for Lu when using an energy window around 208 keV, while the ring-configured system demonstrated a lower bias for a similar CV compared to the Anger system for Tc and for Lu when using an energy window around 113 keV. However, total activity in the phantom tended to be overestimated in both systems for these cases.
The ring-configured CZT system is a viable alternative to the dual-headed Anger system equipped with medium-energy collimators for Lu-SPECT and shows a potential advantage for activity-concentration estimation when operated at 113 keV. However, further consideration of the preservation of total activity is warranted.
目的是比较使用双头安捷伦单光子发射计算机断层扫描（SPECT）系统和环形配置的碲锌镉（CZT）SPECT系统进行镥（Lu）-SPECT活度浓度估计时的偏差和精密度。分别在208 keV和113 keV能量下对成像进行了研究。
在配备5/8英寸碘化钠（铊）晶体的GE Discovery 670系统（双头安捷伦系统）和GE StarGuide（环形配置的CZT系统）上进行了体模实验。NEMA正电子发射断层显像（PET）体模中的六个球体（1.2 mL至113 mL）分别填充了锝（Tc）和镥。研究了两个系统在每个10分钟的六个时间帧内估计球体活度浓度的平均相对误差和变异系数（CV）。对于镥，还对一个具有两个球体（10 mL和25 mL）的人体模型进行了类似采集，该人体模型置于具有非放射性背景且球体与背景比为15:1的肝脏中。使用有序子集期望最大化（OS-EM）算法进行断层重建，共10个子集，并对衰减、散射和距离依赖性空间分辨率进行了补偿。对于安捷伦系统，使用了多达40次迭代，对于环形配置的CZT系统，使用了多达30次迭代。
当使用约208 keV的能量窗时，两个系统对镥的平均相对误差和CV相似；而当使用约113 keV的能量窗时，与安捷伦系统相比，环形配置系统在CV相似的情况下对Tc和镥的偏差更低。然而，在这些情况下，两个系统对体模中的总活度均有高估倾向。
对于Lu-SPECT，环形配置的CZT系统是配备中能准直器的双头安捷伦系统的可行替代方案，并且在113 keV下运行时在活度浓度估计方面显示出潜在优势。然而，有必要进一步考虑总活度的保留问题。
