Evaluation of Radio Frequency-Induced Heating near Fixed Orthodontic Appliances during MRI Examination at 3 Tesla
نویسندگان
چکیده
The purpose of this paper is to assess the added risk pose by radio frequency (RF) induced heating near fixed orthodontic appliances in patients undergoing MRI examination at 3 Tesla. Three of the most commonly used types of fixed orthodontic appliances: Palatal expander (Hyrax) Lingual Bar and Multibracket-/-band braces were investigated using a head phantom and positioned to match the in-vivo situation. Measurements were performed on a 3T MRI system (Siemens Magnetom Verio, Erlangen, Germany) using a Turbo Spin Echo (TSE) pulse sequence that is generating high RF energy, thus, ensuring a worst-case scenario. The measuring points were identified previously through numerical modelling of the Specific Absorption Rate (SAR) of the three appliances. Following numerical modelling, hot spots were identified, which are characterized by the highest values of SAR, and temperature probes were place in these regions. Temperature elevation was between 0.3C to 0.8C in all studied configurations confirming that these fixed orthodontic devices do not present a risk from RF overheating during an MRI examination at 3 Tesla.
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