A standard protocol for performance evaluation of positron emission mammography (PEM) systems has not yet been established. In this work we propose a methodology based on the design of specific phantoms for this imaging modality with component dimensions in accordance with typical breast lesion sizes together with the adaptation of current international protocols designed for clinical and preclinical positron emission tomographs (PET) systems. This methodology was used to evaluate the performance of the Flex Solo II PEM scanner in terms of spatial resolution, uniformity and contrast lesion detectability, recovery coefficients and spill-over ratios. Positron range effects were studied with ¹⁸F and ⁶⁸Ga, which have very different energy spectra. Our results indicate that in-plane spatial resolution of the system is around 3.0 mm and 4.4 mm for ¹⁸F and ⁶⁸Ga, respectively. Lesion detectability tests with sphere diameters between 4 and 10 mm confirmed that the PEM system can resolve all the spheres (hot or cold). Percent contrast values for ¹⁸F lie between 6%–38% and 34%–51% for hot- and cold- spheres, respectively; the corresponding intervals for ⁶⁸Ga are lower, 4%–25% and 32%–44%. Regarding uniformity quantification, the system shows percentage standard deviations within 4.9%–5.7%, while the percent background variability measurements ranged between 6.7% and 10.9% for both radionuclides. Recovery coefficients measured with hot rod diameters between 1.5 and 9 mm, have values between 0.2–1.05 and 0.17–0.69 for ¹⁸F and ⁶⁸Ga, respectively. Spill-over ratios have large values (0.22 in average) for both radionuclides. Our results indicate that the phantoms and the methodology developed in this work can serve as the basis for establishing an image quality protocol for the systematic evaluation of PEM systems, with a potential extension for performance evaluation of dedicated breastPET scanners.

尚未建立用于评估正电子放射钼靶（PEM）系统性能的标准协议。在这项工作中，我们提出了一种基于针对这种成像方式的特定体模设计的方法学，该模型具有与典型乳腺病变大小相对应的组件尺寸，并适用于为临床和临床前正电子发射断层扫描仪（PET）系统设计的当前国际协议。该方法学被用来评估Flex Solo II PEM扫描仪在空间分辨率，均匀性和对比病灶可检测性，恢复系数和溢出率方面的性能。用¹⁸ F和⁶⁸研究正电子射程效应Ga，具有不同的能谱。我们的结果表明，对于¹⁸ F和⁶⁸ Ga，系统的平面内空间分辨率分别约为3.0 mm和4.4 mm 。球直径在4到10 mm之间的病灶可检测性测试证实，PEM系统可以分辨所有球（热或冷）。热球和冷球的¹⁸ F对比度百分比分别在6％–38％和34％–51％之间。⁶⁸的相应间隔Ga较低，分别为4％–25％和32％–44％。关于均匀度定量，系统显示标准偏差百分比在4.9％–5.7％之内，而两种放射性核素的背景变异性百分比测量值均在6.7％至10.9％之间。用热棒直径在1.5和9 mm之间测得的恢复系数，对于¹⁸ F和⁶⁸ Ga分别具有0.2-1.05和0.17-0.69的值。两种放射性核素的溢出比率均具有较大的值（平均0.22）。我们的结果表明，在这项工作中开发的模型和方法可以作为建立图像质量协议以对PEM系统进行系统评估的基础，并可以扩展专用BreastPET扫描仪的性能评估。