Analysis of magnetic resonance image quality using an in-house phantom: Gamma knife application

Magnetic Resonance Imaging (MRI) is increasingly used for purposes of radiosurgery and radiotherapy planning. This imaging modality can explore the physical properties of tissue with great details, especially for the brain. However, the geometric distortion is reasonably occurred and can make significant differences in certain MR application such as, localization in Gamma Knife Radiosurgery. Therefore, the geometric distortion measurement and correction should be applied. In this study, an in-house phantom was developed to measure not only geometric distortion, but also uniformity and high contrast spatial resolution of MR image. The phantom attached to Leksell stereotactic frame was scanned using 1.5T MRI GE. T1-Bravo and T2-Fiesta scan protocol were applied. Standard MRI phantom, Magphan SMR100, was used as data comparison. The result shows that geometric distortion could not be found either in Magphan SMR 100 or in-house phantom images. PIU of the in-house phantom image generated by T1-Bravo and T2-Fiesta scan protocol was around of 79.57% and 56.39%, respectively. Furthermore, the high contrast spatial resolution of the in-house phantom images was 1.0 lp/cm lower compared to Magphan SMR100 phantom images. For this study, it was concluded that the in-house phantom could be employed to analyze MR image quality, yet still needs some improvements, especially for uniformity module.