Bias and precision of SPECT-based ¹⁷⁷Lu activity-concentration estimation using a ring-configured solid-state versus a dual-headed anger system.

IF 3 2区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

EJNMMI Physics Pub Date : 2024-11-04 DOI:10.1186/s40658-024-00693-5

Anna Stenvall, Irma Ceric Andelius, Elias Nilsson, Albin Lindvall, Erik Larsson, Johan Gustafsson

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引用次数: 0

Abstract

Background: The aim was to compare bias and precision for ¹⁷⁷Lu-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.

Methods: 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 ^99mTc and ¹⁷⁷Lu, 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 ¹⁷⁷Lu, 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.

Results: The two systems showed similar mean relative errors and CVs for ¹⁷⁷Lu 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 ^99mTc and for ¹⁷⁷Lu when using an energy window around 113 keV. However, total activity in the phantom tended to be overestimated in both systems for these cases.

Conclusions: The ring-configured CZT system is a viable alternative to the dual-headed Anger system equipped with medium-energy collimators for ¹⁷⁷Lu-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.

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使用环形固态配置与双头愤怒系统进行基于 SPECT 的 177Lu 活性浓度估算的偏差和精度。

背景：目的是比较使用双头安格 SPECT 系统和环形配置的 CZT SPECT 系统估算 177Lu-SPECT 活性浓度的偏差和精确度。研究分别针对 208 keV 和 113 keV 的成像：在配有 5/8'' NaI(Tl)晶体的 GE Discovery 670 系统（双头 Anger 系统）和 GE StarGuide 系统（环形配置的 CZT 系统）上进行了模拟实验。在 NEMA PET 人体模型中的六个球体（1.2 mL 至 113 mL）中分别注入了 99mTc 和 177Lu。研究了两个系统在六个时间段（每个 10 分钟）内估计球体活性浓度的平均相对误差和变异系数 (CV)。对于 177Lu，还对一个拟人模型进行了类似的采集，该模型有两个球体（10 mL 和 25 mL），位于无放射性背景的肝脏中，球体与背景的比例为 15:1。使用 OS-EM 对 10 个子集进行了断层重建，并对衰减、散射和与距离相关的空间分辨率进行了补偿。安杰尔系统最多迭代 40 次，环形配置的 CZT 系统最多迭代 30 次：当使用 208 keV 左右的能量窗口时，两种系统对 177Lu 显示出相似的平均相对误差和 CV，而当使用 113 keV 左右的能量窗口时，环形配置系统对 99mTc 和 177Lu 显示出比 Anger 系统更低的偏差和相似的 CV。然而，在这些情况下，两种系统都倾向于高估模型中的总放射性活度：环形配置的 CZT 系统是 177Lu-SPECT 中配备中等能量准直器的双头安格系统的可行替代方案，并在 113 keV 下运行时显示出活动浓度估计的潜在优势。不过，还需要进一步考虑总放射性活度的保存问题。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

EJNMMI Physics Physics and Astronomy-Radiation

CiteScore

6.70

自引率

10.00%

发文量

审稿时长

13 weeks

期刊介绍： EJNMMI Physics is an international platform for scientists, users and adopters of nuclear medicine with a particular interest in physics matters. As a companion journal to the European Journal of Nuclear Medicine and Molecular Imaging, this journal has a multi-disciplinary approach and welcomes original materials and studies with a focus on applied physics and mathematics as well as imaging systems engineering and prototyping in nuclear medicine. This includes physics-driven approaches or algorithms supported by physics that foster early clinical adoption of nuclear medicine imaging and therapy.