Kennedy John A, Palchan-Hazan Tala, Keidar Zohar
Department of Nuclear Medicine, Rambam Health Care Campus, P.O.B. 9602, 3109601, Haifa, Israel.
Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
EJNMMI Phys. 2025 Jan 20;12(1):4. doi: 10.1186/s40658-025-00715-w.
A recently released digital solid-state positron emission tomography/x-ray CT (PET/CT) scanner with bismuth germanate (BGO) scintillators provides an artificial intelligence (AI) based system for automatic patient positioning. The efficacy of this digital-BGO system in patient placement at the isocenter and its impact on image quality and radiation exposure was evaluated.
The digital-BGO PET/CT with AI-based auto-positioning was compared (χ, Mann-Whitney tests) to a solid-state lutetium-yttrium oxyorthosilicate (digital-LYSO) PET/CT with manual patient positioning (n = 432 and 343 studies each, respectively), with results split into groups before and after the date of a recalibration of the digital-BGO auto-positioning camera. To measure the transverse displacement of the patient center from the scanner isocenter (off-centering), CT slices were retrospectively selected and automatically analyzed using in-house software. Noise was measured as the coefficient of variation within the liver of absolute Hounsfield units referenced to air. Radiation exposure was recorded as dose-length product (DLP). Off-centering measurements were validated by a phantom study.
The phantom validation study gave < 1.6 mm error in 15 off-centering measurements. Patient off-centering was biased 1.92 ± 1.79 cm (mean ± standard deviation) in the posterior direction which was significantly different from the 0.22 ± 1.21 cm bias in the left lateral direction (p < 0.0001, Wilcoxon). After recalibration, 27% (38/140) of the studies had off-centering results > 2.5cm for the digital-BGO, which was significantly better than the 49% (143/292, p < 0.001) before recalibration and better than for the digital-LYSO: 54% (119/222, p < 0.001) before and 55% (66/121, p < 0.001) after. On average, CT image quality was superior for non-obese patients who were most closely aligned with the isocenter: noise increased by 3.2 ± 0.1% for every 1 cm increase in off-centering. DLP increased by 144 ± 22 Gy cm for every 1 cm increase in anterior off-centering.
AI-based automatic patient positioning in a digital-BGO PET/CT scanner significantly reduces patient off-centering, thereby improving image quality and ensuring proper radiation exposure.
最近发布的一款配备锗酸铋（BGO）闪烁体的数字固态正电子发射断层扫描/ X射线计算机断层扫描（PET/CT）扫描仪提供了一种基于人工智能（AI）的自动患者定位系统。评估了这种数字BGO系统在将患者放置于等中心的有效性及其对图像质量和辐射暴露的影响。
将具有基于AI自动定位功能的数字BGO PET/CT与具有手动患者定位功能的固态正硅酸镥钇（数字LYSO）PET/CT进行比较（χ检验、曼-惠特尼检验）（分别为432例和343例研究），结果分为数字BGO自动定位相机重新校准日期之前和之后的组。为了测量患者中心与扫描仪等中心的横向位移（偏心），回顾性选择CT切片并使用内部软件进行自动分析。噪声测量为以空气为参考的绝对亨氏单位在肝脏内的变异系数。辐射暴露记录为剂量长度乘积（DLP）。通过体模研究验证偏心测量。
体模验证研究在15次偏心测量中的误差<1.6毫米。患者偏心在后方方向上有1.92±1.79厘米（平均值±标准差） 的偏差，这与左侧方向上0.22±1.21厘米的偏差有显著差异（p<0.0001，威尔科克森检验）。重新校准后，数字BGO的研究中有27%（38/140）的偏心结果>2.5厘米，这明显优于重新校准前的49%（143/292，p<0.001）以及数字LYSO：重新校准前为54%（119/222，p<0.001），重新校准后为55%（66/121，p<0.001）。平均而言，对于与等中心最接近对齐的非肥胖患者，CT图像质量更好：偏心每增加1厘米，噪声增加3.2±0.1%。前方偏心每增加1厘米，DLP增加144±22 Gy·cm。
数字BGO PET/CT扫描仪中基于AI的自动患者定位可显著减少患者偏心，从而提高图像质量并确保适当的辐射暴露。
