Kei Ma Wang, Hogg Peter, Norton Sue
Radiol Technol. 2014 May-Jun;85(5):479-85.
To determine how kilovoltage (kV), milliampere seconds (mAs), and focal spot size affect perceptual image quality using a hand phantom.
Using computed radiography, 70 images of a posteroanterior (PA) oblique hand phantom were acquired with different kilovoltage and milliampere second values using large and small focal spot sizes. Images were displayed on quality-controlled monitors with dimmed ambient lighting. The look-up table for hand radiography was used for image display. Five diagnostic radiographers scored each image for perceptual image quality against a reference image using a 5-point Likert scale.
No significant difference in image quality was found between small and large focal spot sizes at different kilovoltage (P = .46) and milliampere second (P = .56) values. As milliampere seconds increase, perceptual image quality increases gradually from 0.4 mAs to 4 mAs, after which perceptual image quality begins to deteriorate. When kilovoltage increases to within the range of 40 kV to 55 kV, perceptual image quality increases; image quality remains stable after 55 kV.
This study shows that both large and small focal spot sizes produce images of similar quality, and a wide range of kilovoltage and milliampere seconds can be used to produce images of acceptable quality. The implications of these findings include the potential for extending the life of radiography equipment and the potential for reducing the dose patients receive during appendicular examinations.
Large focal spot size can be used for PA oblique hand imaging without affecting perceptual image quality. Perceptual image quality remains acceptable and stable for a wide range of kilovoltage and milliampere second values. Optimization of these technical factors to achieve image quality is critical to avoiding higher radiation doses than necessary.
使用手部模型确定千伏（kV）、毫安秒（mAs）和焦点尺寸如何影响感知图像质量。
使用计算机X线摄影，使用大焦点和小焦点尺寸，通过不同的千伏和毫安秒值采集70张后前位（PA）斜位手部模型图像。图像在环境光调暗的质量控制显示器上显示。手部X线摄影的查找表用于图像显示。五名诊断放射技师使用5点李克特量表，将每张图像与参考图像进行比较，对感知图像质量进行评分。
在不同的千伏（P = 0.46）和毫安秒（P = 0.56）值下，小焦点和大焦点尺寸之间的图像质量没有显著差异。随着毫安秒增加，感知图像质量从0.4 mAs逐渐增加到4 mAs，之后感知图像质量开始下降。当千伏增加到40 kV至55 kV范围内时，感知图像质量增加；55 kV后图像质量保持稳定。
本研究表明，大焦点和小焦点尺寸均可产生质量相似的图像，并且可以使用广泛的千伏和毫安秒值来产生质量可接受的图像。这些发现的意义包括延长X线摄影设备使用寿命的可能性以及减少患者在四肢检查期间接受剂量的可能性。
大焦点尺寸可用于PA斜位手部成像，而不影响感知图像质量。对于广泛的千伏和毫安秒值，感知图像质量保持可接受且稳定。优化这些技术因素以实现图像质量对于避免不必要的高辐射剂量至关重要。
