Poklicna izpostavljenost napravam za slikanje z magnetno resonanco, ocena tveganja in ukrepi varstva pred sevanji : magistrsko delo

Godec, Matic (author), Mekiš, Nejc (mentor), Gajšek, Peter (comentor), Fošnarič, Miha (reviewer)

Uvod: Zaposleni, ki delajo v območju naprav za MR slikanje so izpostavljeni različnim oblikam elektromagnetnih polj (EMP), ki se razlikujejo glede na frekvenco in trajanje izpostavljenosti. Za omejitev poklicne izpostavljenosti in varstvo pred zdravstvenimi tveganji zaradi EMP so mednarodne organizacije in odbori izdali različna varnostna priporočila in smernice. Direktiva 2013/35/EU določa specifične mejne vrednosti izpostavljenosti in opozorilne vrednosti za preprečitev posrednih in neposrednih biofizikalnih učinkov na zdravje zaposlenih. Namen: Namen raziskave je bil ugotoviti izpostavljenost zaposlenih, ki opravljajo delo v območju naprav za MR slikanje ter rezultate meritev primerjati z mejnimi in opozorilnimi vrednostmi, ki jih določa direktiva 2013/35/EU. Metode dela: Meritve Bo polja smo izvedli z uporabo merilne naprave Metrolab THM 1176. Za meritve impulznih visokofrekvenčnih polj smo uporabili dva merilna postopka. Z merilno napravo SRM-3006 smo izvedli točkovne meritve impulznih VF EMP v času izvedbe kliničnega protokola. Istočasno smo izvajali še meritve z napravo Narda NBM-550 na fiksnem merilnem mestu. Meritve nizkofrekvenčnega gradientnega magnetnega polja smo izvedli z uporabo merilne naprave ELT 400, ki je bila preko analognega vmesnika priključena na osciloskop. Rezultati: Najvišja vrednost Bo polja v območju izven prostora z MR napravo je bila izmerjena na merilnem mestu št. 2 in je znašala 0,61 mT. Najvišja vrednost Bo polja znotraj območja z MR napravo je bila izmerjena na merilnem mestu št. 10, ki označuje vhod v odprtino naprave in je znašala 1000 mT. Analiza meritev je pokazala, da so bile izpeljane opozorilne vrednosti za dB/dt presežene pri meritvah, ki so bile izvedene v prostoru z MR napravo na merilnih mestih 29 (4,03 T/s) in Y (7,08 T/s). Najvišja vrednost električne poljske jakosti je znašala 22,92 V/m, kar predstavlja 37,57 % opozorilne vrednosti Direktive 2013/35/EU za frekvenčno območje 10-400 MHz. Razprava in zaključek: Na podlagi rezultatov meritev in naših ugotovitev lahko potrdimo, da je poklicna izpostavljenost med rutinskimi postopki na MR oddelku Onkološkega inštituta Ljubljana skladna z mejnimi in opozorilnimi vrednostmi Direktive 2013/35/EU.

• Language: Slovenian
• Keywords: magistrska dela, radiološka tehnologija, magnetna resonanca, poklicna izpostavljenost, ocena tveganja, ukrepi varstva pred sevanji
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [M. Godec]
• Year: 2024
• Number of pages: 100 str., [3] str. pril.
• PID: 20.500.12556/RUL-164018
• UDC: 616-07
• COBISS.SI-ID: 211798531
• Publication date in RUL: 16.10.2024

Secondary language

• Language: English
• Title: Occupational exposure to MRI, risk assessment and protection measures : master thesis

Abstract

Introduction: Medical personnel working in the MRI environment are exposed to various forms of electromagnetic fields (EMF) that vary in frequency and duration of exposure. Many international organizations and committees have developed various safety guidelines to limit occupational exposure and provide protection against known adverse health effects of EMF. Directive 2013/35/EU defines specific exposure limit values and the action levels to prevent all known indirect and direct biophysical health effects caused by EMF. Purpose: The purpose of this paper was to assess the occupational exposure to EMF in MRI clinical environment and to verify its compliance with exposure limit values and action levels set by Directive 2013/35/EU. Methods: The measurements of the static magnetic field have been performed using Metrolab THM 1176 measuring device. Two exposure recording systems were used to assess exposure to high frequency RF fields. Spot measurements were performed using SRM-3006. Simultaneously we measured electric field strength of high frequency RF fields on a fixed grid using Narda NBM 550. Exposure to low frequency gradient magnetic fields involved a measuring system of a Narda ELT 400 that was connected to the oscilloscope via analogue output of the probe. Results: The peak value of the Bo fringe field in the area outside the room with the MRI scanner was measured at the measuring spot 2 (0,61 mT). The peak value of the Bo field inside the room with the MRI scanner reached 1000 mT and was measured at the measuring spot 10. The analysis of low frequency gradient magnetic field measurements showed that the derived action levels for dB/dt were exceeded in the proximity of the MRI device during ongoing clinical protocol at two measuring spots. Peak values of dB/dt measured at this two measuring spots reached 4,03 T/s (measuring spot 29) and 7,08 T/s (measuring spot Y). The peak incident electric field strength was measured at 22,92 V/m, which represents 37,57 % of the action value for the frequency range 10-400 MHz. Discussion and conclusion: Based on the results of the measurements and our findings, we can confirm that the occupational exposure during routine clinical procedures at the MRI department of the Oncology Institute of Ljubljana complies with the exposure limit values and action levels set by Directive 2013/35/EU.

• Keywords: master's theses, radiologic technology, magnetic resonance imaging, occupational exposure, risk assessment, protection measures