Narita Akihiro, Ohkubo Masaki, Ohsugi Yuki
Department of Radiological Technology, Graduate School of Health Sciences, Niigata University.
Division of Radiology, Niigata University Medical and Dental Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2024 Sep 20;80(9):923-927. doi: 10.6009/jjrt.2024-1486. Epub 2024 Aug 15.
The measurement of slice sensitivity profile (SSP) in non-helical CT is conventionally performed by repeated scans with moving a micro-coin phantom little by little in the longitudinal direction at a small interval, which is reliable but laborious and time-consuming. The purpose of this study was to propose a simple method for measuring the SSP in non-helical CT based on a previous method that measured the slice thickness using a tilted metal wire.
In the proposed method, a CT image was obtained by scanning a wire tilted at an angle θ=30° to the scan plane. By deconvolving the image with the point spread function (PSF) measured at the scanner, we obtained an image that was not affected by the PSF blurring. The CT value profile along the wire was acquired on the obtained image. The SSP was determined by multiplying the profile by tan θ. In addition, the SSP was measured by the conventional method using a micro-coin phantom and compared with the SSP obtained by the proposed method.
The SSP measured by the proposed method agreed well with that measured by the conventional method. The full-width at half-maximum values of these SSPs were the same.
The proposed method was demonstrated to easily and accurately measure the SSP in non-helical CT.
在非螺旋CT中，切片灵敏度分布（SSP）的测量传统上是通过在纵向方向上以小间隔逐渐移动微型硬币模体进行重复扫描来完成的，这种方法可靠但费力且耗时。本研究的目的是基于先前使用倾斜金属丝测量切片厚度的方法，提出一种在非螺旋CT中测量SSP的简单方法。
在所提出的方法中，通过扫描与扫描平面成θ = 30°角倾斜的金属丝来获取CT图像。通过用在扫描仪处测量的点扩散函数（PSF）对图像进行去卷积，我们获得了不受PSF模糊影响的图像。在所获得的图像上获取沿金属丝的CT值分布。通过将该分布乘以tan θ来确定SSP。此外，使用微型硬币模体通过传统方法测量SSP，并与通过所提出的方法获得的SSP进行比较。
所提出的方法测量的SSP与传统方法测量的SSP非常吻合。这些SSP的半高全宽值相同。
所提出的方法被证明能够轻松、准确地测量非螺旋CT中的SSP。
