Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, AT-1090 Vienna, Austria.
AJR Am J Roentgenol. 2011 Aug;197(2):W318-23. doi: 10.2214/AJR.10.5505.
A newly developed computed radiography (CR) detector that uses a storage phosphor plate made of needle-shaped crystals provides improved dose efficiency. The aim of our study was to compare the image quality of standard-dose CR and dose-reduced CR achieved using needle technology for knee imaging in a clinical setting.
We compared standard CR images obtained using a powder-structured image plate (PIP) (ADC Compact Plus) with images obtained using the new needle-structured image plate (NIP) (DX-S). In 30 consecutive patients with knee pain willing to participate in this study, anteroposterior knee radiographs were acquired with both systems at a standard dose. In addition, NIP images were obtained with approximately 75% and 50% of the standard dose (corresponding incident doses: 300, 235, and 154 μGy, respectively). Images were evaluated in a blinded, side-by-side comparison. Six radiologists determined whether there was an appreciable difference in image quality at five anatomic landmarks in regions with high and low differences of attenuation. They also assessed the delineation of selected abnormalities and ranked them using a 10-point scale. The rating scores were tested for statistical differences using an analysis of variance with repeated measures.
The mean overall rating scores for the evaluation of anatomic landmarks were 6.97 for NIP images obtained at full dose, 6.48 for NIP images obtained at about 75% dose, 5.47 for NIP images obtained at half dose, and 6.01 for PIP images. There was a significant difference in favor of the CR system with an NIP at the same dose level (p < 0.05). The NIP images obtained at a dose of about 75% were also ranked significantly better than the PIP images with regard to the depiction of both anatomic landmarks and abnormalities. The readers ranked half-dose NIP images inferior to the PIP images with regard to abnormalities and anatomic landmarks in areas with high attenuation, whereas in areas with low attenuation, the image quality was regarded as equivalent to the standard technique.
NIP technology allows a dose reduction of approximately 25% compared with PIP while still providing higher image quality. Even at the half-dose level, there was no relevant loss of image quality with regard to the delineation of anatomic landmarks in areas with low attenuation in anteroposterior knee images. The higher dose efficiency of the needle-detector CR technology compared with conventional CR can be used either for dose reduction or for improved image quality.
一种新开发的计算机射线照相（CR）探测器使用针状晶体制成的存储磷光板，可提高剂量效率。我们的研究目的是比较标准剂量 CR 和使用针技术实现的剂量降低 CR 在临床环境下进行膝关节成像的图像质量。
我们比较了使用粉末结构图像板（PIP）（ADC Compact Plus）获得的标准 CR 图像和使用新型针状结构图像板（NIP）（DX-S）获得的图像。在 30 名连续有膝关节疼痛且愿意参加本研究的患者中，使用两种系统以标准剂量获得前后位膝关节射线照相。此外，使用大约 75%和 50%的标准剂量（相应的入射剂量分别为 300、235 和 154 μGy）获得 NIP 图像。以盲法、并排比较的方式评估图像。六名放射科医生在高和低衰减差异的五个解剖标志处确定图像质量是否有明显差异。他们还评估了选定异常的描绘并使用 10 分制对其进行排名。使用具有重复测量的方差分析测试评分的统计学差异。
在评估解剖标志的总体平均评分中，全剂量 NIP 图像为 6.97，约 75%剂量 NIP 图像为 6.48，半剂量 NIP 图像为 5.47，PIP 图像为 6.01。在相同剂量水平下，具有 NIP 的 CR 系统具有显著差异（p <0.05）。与 PIP 图像相比，75%剂量的 NIP 图像在描绘解剖标志和异常方面的评分也显著更高。与 PIP 图像相比，读者对半剂量 NIP 图像在高衰减区域的异常和解剖标志的评分较低，而在低衰减区域，图像质量被认为与标准技术相当。
与 PIP 相比，NIP 技术可将剂量降低约 25%，同时仍提供更高的图像质量。即使在半剂量水平，在前膝关节射线照相中低衰减区域的解剖标志描绘方面，也没有明显的图像质量损失。与传统 CR 相比，针式探测器 CR 技术的更高剂量效率可用于降低剂量或提高图像质量。
