Measurement of the Weighted Peak Level for Occupational Exposure to Gradient Magnetic Fields for 1.5 and 3 Tesla Mri Body Scanners

Bonutti, Faustino; Tecchio, M.; Maieron, Marta; Trevisan, D.; Negro, C.; Calligaris, F.

doi:10.1093/rpd/ncv308

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…A THM1176 3-Axis hall magnetometer was positioned at a height of 1 m from the ground, with probe sensor facing the scanner magnet. The height was chosen to representative where most of the MRI activities are performed and as an approximate height chosen in a study conducted by Bonutti et al [25] and Fatahi et al [26].…”

Section: Static Magnetic Fields Measurements: Round Onementioning

confidence: 99%

Exposure levels of radiofrequency magnetic fields and static magnetic fields in 1.5 and 3.0 T MRI units

2021

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Magnetic resonance imaging (MRI) staff is exposed to a complex mixture of electromagnetic fields from MRI units. Exposure to these fields results in the development of transient exposure-related symptoms. This study aimed to investigate the exposure levels of radiofrequency (RF) magnetic fields and static magnetic fields (SMFs) from 1.5 and 3.0 T MRI scanners in two public hospitals in the Mangaung Metropolitan region, South Africa. The exposure levels of SMFs and RF magnetic fields were measured using the THM1176 3-Axis hall magnetometer and TM-196 3 Axis RF field strength meter, respectively. Measurements were collected at a distance of 1 m (m) and 2 m from the gantry for SMFs when the brain, cervical spine and extremities were scanned. Measurements for RF magnetic fields were collected at a distance of 1 m with an average scan duration of six minutes. Friedman’s test was used to compared exposure mean values from two 1.5 T scanners, and Wilcoxon test with Bonferroni adjustment was used to identify where the difference between exist. The Shapiro–Wilk test was also used to test for normality between exposure levels in 1.5 and 3.0 T scanners. The measured peak values for SMFs from the 3.0 T scanner at hospital A were 1300 milliTesla (mT) and 726 mT from 1.5 T scanner in hospital B. The difference in terms of SMFs exposure levels was observed between two 1.5 T scanners at a distance of 2 m. The difference between 1.5 T scanners at 1 m was also observed during repeated measurements when brain, cervical spine and extremities scans were performed. Scanners’ configurations, magnet type, clinical setting and location were identified as factors that could influence different propagation of SMFs between scanners of the same nominal B0. The RF pulse design, sequence setting flip-angle and scans performed influenced the measured RF magnetic fields. Three scanners were complaint with occupational exposure guidelines stipulated by the ICNIRP; however, peak levels that exist at 1 m could be managed through adoption of occupational health and safety programs.

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Section: Static Magnetic Fields Measurements: Round Onementioning

confidence: 99%

Exposure levels of radiofrequency magnetic fields and static magnetic fields in 1.5 and 3.0 T MRI units

2021

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“…Therefore, both ICNIRP guidelines [50,67] and EU Directive [17,68] recommend the Weighted Peak Method (WPM) for assessing compliance with exposure limits in case of complex waveforms. WPM can be implemented either in time-domain (hardware or software implementation) [56,57,69] or in frequency-domain [48,70]. The result of this approach is the WP index, whose value must be below 1 to ensure compliance.…”

Section: Exposure Assessmentmentioning

confidence: 99%

“…The result of this approach is the WP index, whose value must be below 1 to ensure compliance. Some commercial instruments permit the implementation of the weighted-peak approach [56,57], according to the ICNIRP 2003 [71] statement on complex waveforms and the ICNIRP 1998 [13] reference levels.…”

Section: Exposure Assessmentmentioning

confidence: 99%

Occupational exposure to electromagnetic fields in magnetic resonance environment: an update on regulation, exposure assessment techniques, health risk evaluation, and surveillance

Hartwig

Virgili²,

Mattei³

et al. 2021

Med Biol Eng Comput

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Magnetic Resonance Imaging (MRI) is one of the most-used diagnostic imaging methods worldwide. There are ∼50,000 MRI scanners worldwide each of which involves a minimum of five workers from different disciplines who spend their working days around MRI scanners. This review analyses the state-of-art of literature about the several aspects of the occupational exposure to electromagnetic fields (EMF) in MRI: regulations, literature studies on biological effects, and health surveillance are addressed here in detail, along with a summary of the main approaches for exposure assessment. The original research papers published from 2013 to 2021 in international peer-reviewed journals, in the English language, are analysed, together with documents published by legislative bodies. The key points for each topic are identified and described together with useful tips for precise safeguarding of MRI operators, in terms of exposure assessment, studies on biological effects, and health surveillance.

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“…Abbreviation: MRI, magnetic resonance imaging. Literature references used: MRI 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ) ; Magnetic stimulation 35 , 36 , 37 , 38 , 39 , 40 ) ; Magnetotherapy 39 , 41 ) ; Diathermy 6 , 39 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ) ; Hyperthermia 5 , 55 , 56 ) ; Electrosurgery 6 , 7 , 37 , 39 , 52 , 57 , 58 , 59 , 60 , 61 ) ; Other (intensive care, emergency, pharmacy, physiotherapy, dentistry, ultrasound, defibrillator) 39 , 41 , 54 , 62 ...…”

Section: Resultsmentioning

confidence: 99%

Occupational exposure to electromagnetic fields from medical sources

Stam

Yamaguchi-Sekino

2018

INDUSTRIAL HEALTH

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High exposures to electromagnetic fields (EMF) can occur near certain medical devices in the hospital environment. A systematic assessment of medical occupational EMF exposure could help to clarify where more attention to occupational safety may be needed. This paper seeks to identify sources of high exposure for hospital workers and compare the published exposure data to occupational limits in the European Union. A systematic search for peer-reviewed publications was conducted via PubMed and Scopus databases. Relevant grey literature was collected via a web search. For each publication, the highest measured magnetic flux density or internal electric field strength per device and main frequency component was extracted. For low frequency fields, high action levels may be exceeded for magnetic stimulation, MRI gradient fields and movement in MRI static fields. For radiofrequency fields, the action levels may be exceeded near devices for diathermy, electrosurgery and hyperthermia and in the radiofrequency field inside MRI scanners. The exposure limit values for internal electric field may be exceeded for MRI and magnetic stimulation. For MRI and magnetic stimulation, practical measures can limit worker exposure. For diathermy, electrosurgery and hyperthermia, additional calculations are necessary to determine if SAR limits may be exceeded in some scenarios.

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Measurement of the Weighted Peak Level for Occupational Exposure to Gradient Magnetic Fields for 1.5 and 3 Tesla Mri Body Scanners

Cited by 5 publications

References 10 publications

Exposure levels of radiofrequency magnetic fields and static magnetic fields in 1.5 and 3.0 T MRI units

Exposure levels of radiofrequency magnetic fields and static magnetic fields in 1.5 and 3.0 T MRI units

Occupational exposure to electromagnetic fields in magnetic resonance environment: an update on regulation, exposure assessment techniques, health risk evaluation, and surveillance

Occupational exposure to electromagnetic fields from medical sources

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