RF Exposure Assessment for Various Poses of Patient Assistant in Open MRI Environment

Seon-Eui Hong,Hyung-Do Choi,Sukhoon Oh

doi:10.3390/app11114967

Abstract

In this study, the radio-frequency (RF) energy exposure of patient assistants was assessed for an open magnetic resonance imaging (MRI) system based on numerical computations of the head and body RF coil. Various poses of the patient assistants were defined to see how poorly they affected the RF energy exposure. For the assessments, the peak spatial-averaged specific absorption rate (SAR) levels were carefully compared with each patient assistant pose based on the finite-difference time domain calculations of RF coil models when the patient was placed in such coils in a 0.3 Tesla open MRI system. Overall, the SAR levels of the patient assistant were much lower than those of the patient. However, significantly increased SAR levels were observed under specific conditions, including a larger loop size of the patient assistants’ arms and a closer distance to the RF coils. A comparably high level of SAR to the patient’s body was also found. More careful investigations are needed to prevent the increase of SAR in patient assistants for open MRI systems at higher field strengths.

Highlights

Diagnostic medical devices based on magnetic resonance imaging (MRI) have taken a major share of the global medical device market owing to their unique features; for example, the technology provides various contrast information, for soft biological tissues, has a high capability to provide 3D cross-sectional visualization of the human body, and has no associated ionizing radiation hazards
The RF exposure levels are dependent on the loaded body parts because more loading in a RF coil requires additional RF power to flip the spins at a specific angle for the desired MRI scans [28]
This helps with analytical comparisons of specific absorption rate (SAR) computations under different MRI scan protocols requiring different levels of RF power

Summary

Introduction

Diagnostic medical devices based on magnetic resonance imaging (MRI) have taken a major share of the global medical device market owing to their unique features; for example, the technology provides various contrast information, for soft biological tissues, has a high capability to provide 3D cross-sectional visualization of the human body, and has no associated ionizing radiation hazards. For these reasons, MRI systems are widely used for clinical and research purposes. A lower image quality is generally expected in a low-field MRI, the open-magnet shape provides a unique MR imaging environment

Methods

Results

Conclusion