基于体模的电子射野影像装置临床成像性能评估

A phantom based evaluation of the clinical imaging performance of electronic portal imaging devices.

作者信息

Tzomakas Marios K, Peppa Vasiliki, Alexiou Antigoni, Karakatsanis Georgios, Episkopakis Anastasios, Michail Christos, Valais Ioannis, Fountos George, Kalyvas Nektarios, Kandarakis Ioannis S

机构信息

Radiation Physics, Materials Technology and Biomedical Imaging Laboratory, Department of Biomedical Engineering, University of West Attica, Egaleo, 12210 Athens, Greece.

General Hospital of Athens Alexandra, Department of Radiotherapy, 11528 Athens, Greece.

出版信息

Heliyon. 2023 Oct 17;9(10):e21116. doi: 10.1016/j.heliyon.2023.e21116. eCollection 2023 Oct.

DOI:10.1016/j.heliyon.2023.e21116

PMID:37916082

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC10616349/

Abstract

PURPOSE

In this study an evaluation of the imaging performance of an electronic portal imaging device (EPID) is presented. The evaluation performed employing the QC-3V image quality phantom.

METHODS

An EPID system of a 6 MV LINAC, was used to obtain images of a QC-3V EPID phantom. The X-ray source to phantom distance was 100 cm and the field size was 15x15 cm. The irradiation conditions comprised Dose Rates (DR) of 200, 400 and 600 for a 2 MU-100 MU range. The Contrast Transfer Function (CTF), the Noise Power Spectrum (NPS), the Normalized Noise Power Spectrum (NNPS) and the Contrast-to-Noise Ratio (CNR) were studied. In addition, an alternative factor showing a frequency related output signal-to-noise ratio (SNR), the Signal-to-Noise-Frequency Response (SNFR), has been introduced. SNFR is a comprehensive quality index, easily determined in clinical environment.

RESULTS

The CTF curves were found comparable to each other. The lowest values were measured at 2 MU and 200 MU/min. Concerning the NPS and NNPS graphs it was found that the values decrease up to approximately 0.3 lp/mm and demonstrate a white noise shape afterwards. SNFR values were found reducing with spatial frequency. Highest CNR were found between the region 7 and 11 of the phantom.

CONCLUSIONS

The influence of MU and DR on EPID performance were investigated. Image quality was assessed using the QC-3V phantom. The presented results can lead to image quality amelioration and act supportively to current image quality control routine protocols.

摘要

目的

本研究对电子射野影像装置（EPID）的成像性能进行了评估。评估采用QC - 3V图像质量模体。

方法

使用一台6兆伏直线加速器的EPID系统获取QC - 3V EPID模体的图像。X射线源到模体的距离为100厘米，射野大小为15×15厘米。照射条件包括在2兆电子伏特至100兆电子伏特范围内，剂量率（DR）分别为200、400和600。研究了对比度传递函数（CTF）、噪声功率谱（NPS）、归一化噪声功率谱（NNPS）和对比度噪声比（CNR）。此外，还引入了一个表示频率相关输出信噪比（SNR）的替代因子，即信号 - 噪声 - 频率响应（SNFR）。SNFR是一个综合质量指标，在临床环境中易于确定。