Proof of concept for low-dose molecular breast imaging with a dual-head CZT gamma camera. Part I. Evaluation in phantoms.
Proof of concept for low-dose molecular breast imaging with a dual-head CZT gamma camera. Part I. Evaluation in phantoms.
复制标题
使用双头 CZT 伽玛相机进行低剂量分子乳腺成像的概念验证。
DOI：
10.1118/1.4718665
复制
发表时间：
2012
期刊：
影响因子：
3.8
通讯作者：
O'Connor,MichaelK
中科院分区：
文献类型：
--
作者：
Hruska,CarrieB;Weinmann,AmandaL;O'Connor,MichaelK
目的：分子乳腺成像（MBI）是一种核医学技术，使用双头碲锌镉（CZT）伽马相机对乳腺中放射性示踪剂Tc-99 m sestamibi的功能性摄取进行成像。在筛查环境中采用MBI的一个重要因素是将Tc-99 m司他米比的必要给药剂量从通常使用的740 MBq减少到约148 MBq，使得MBI的全身有效剂量与筛查乳房X线摄影相当。增加MBI计数灵敏度的方法可以允许必要的施用剂量的成比例减少。我们的目的是通过评估计数灵敏度、空间分辨率和体模模拟中的病变对比度来评估两种计数灵敏度改进方法对图像质量的影响。方法：研究了两种基于双头CZT的MBI系统：LumaGem和Discovery NM 750 b。实施了两种计数灵敏度改进方法：针对专用乳腺成像优化的配准准直器和针对CZT优化的加宽能量接受窗口。通过比较标准准直和能量窗设置[126-154 keV]，测量系统灵敏度、空间分辨率和肿瘤对比噪声比（CNR）（+10%，-10%）]，具有最佳准直和宽能量窗口[110-154 keV（+10%，-21%）]。与这两种系统的标准准直器设计和能量窗相比，使用配准的最佳准直和宽能量窗使系统灵敏度增加了2.8-3.6倍。采用新准直的两种系统的空间分辨率略有下降。在距离准直器表面3 cm处，LumaGem的空间分辨率为4.8 mm和5.6 mm，采用标准和优化准直; Discovery NM 750 b的空间分辨率分别为4.4 mm和4.6 mm，采用标准和优化准直。对于两种系统，在肿瘤深度为1和3 cm时，与直径为8.0和9.2 mm的肿瘤的标准设置相比，使用优化准直和宽能量窗显著改善了CNR。结论：与标准准直器设计和能量窗相比，优化准直器和宽能量窗可显著提高CNR的计数灵敏度和可测量增益，但空间分辨率有所降低。在计算代表148 MBq剂量的低计数密度时，这种权衡导致足够的计数密度和病变对比度，用于检测典型乳房中部≥8 mm的病变（3 cm深）和靠近准直器≥6 mm的病变（1 cm深）。
Purpose:Molecular breast imaging (MBI) is a nuclear medicine technology that uses dual‐head cadmium zinc telluride (CZT) gamma cameras to image functional uptake of a radiotracer, Tc‐99m sestamibi, in the breast. An important factor in adoption of MBI in the screening setting is reduction of the necessary administered dose of Tc‐99m sestamibi from the typically used dose of 740 MBq to approximately 148 MBq, such that MBI's whole‐body effective dose is comparable to that of screening mammography. Methods that increase MBI count sensitivity may allow a proportional reduction in the necessary administered dose. Our objective was to evaluate the impact of two count sensitivity improvement methods on image quality by evaluating count sensitivity, spatial resolution, and lesion contrast in phantom simulations.Methods:Two dual‐head CZT‐based MBI systems were studied: LumaGem and Discovery NM 750b. Two count sensitivity improvement methods were implemented: registered collimators optimized for dedicated breast imaging and widened energy acceptance window optimized for use with CZT. System sensitivity, spatial resolution, and tumor contrast‐to‐noise ratio (CNR) were measured comparing standard collimation and energy window setting [126–154 keV (+10%, −10%)] with optimal collimation and a wide energy window [110–154 keV (+10%, −21%)].Results:Compared to the standard collimator designs and energy windows for these two systems, use of registered optimized collimation and wide energy window increased system sensitivity by a factor of 2.8–3.6. Spatial resolution decreased slightly for both systems with new collimation. At 3 cm from the collimator face, LumaGem's spatial resolution was 4.8 and 5.6 mm with standard and optimized collimation; Discovery NM 750b's spatial resolution was 4.4 and 4.6 mm with standard and optimized collimation, respectively. For both systems, at tumor depths of 1 and 3 cm, use of optimized collimation and wide energy window significantly improved CNR compared to standard settings for tumors 8.0 and 9.2 mm in diameter. At the closer depth of 1 cm, optimized collimation and wide energy window also significantly improved CNR for 5.9 mm tumors on Discovery NM 750b.Conclusions:Registered optimized collimation and wide energy window yield a substantial gain in count sensitivity and measurable gain in CNR, with some loss in spatial resolution compared to the standard collimator designs and energy windows used on these two systems. At low‐count densities calculated to represent doses of 148 MBq, this tradeoff results in adequate count density and lesion contrast for detection of lesions ≥8 mm in the middle of a typical breast (3 cm deep) and lesions ≥6 mm close to the collimator (1 cm deep).