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

Proposed Safety Guidelines for Patient Assistants in an Open MRI Environment

The wide-open side of an open magnetic resonance imaging (MRI) system allows a patient to easily contact the patient assistant during MRI scans. A wide-open-shaped magnet is highly effective when interventional procedures are necessary. Patient assistants can provide comfort by holding a part of the patient's body. Because current regulations or guidelines are concerned with only patient radio frequency (RF) safety, investigations on the safety of patient assistants exposed to high-magnetic field MRI (up to 1.2 T) are required. In this study, five different poses of patient assistants were numerically simulated at a 1.2 T open MRI system to determine the impact of poses on the RF exposure level. The 10-g averaged specific absorption rate (SAR) levels were analyzed for the poses of each patient assistant wearing gloves. Compared with the patient, up to 29.8% of the patient SAR was observed in the patient assistant. When the patient assistant wore latex gloves, a 63.7% reduction in the 10-g averaged SAR level was observed, which could be a remedy to minimize possible RF hazards. To prevent possible RF hazards during MRI scans, certain clauses regarding the patient assistant's poses or wearing gloves must be added to the existing MRI screening forms.

Perceived safety of MRI units in the two public hospitals within the central region of South Africa: A pilot study among four MR staff

Magnetic resonance scanners are considered safe but comes with substantive safety risks to patients seeking radiological diagnostics and health care professionals. This pilot study aimed to assess the safety compliance of MRI units commonly used in the clinical diagnostic imaging of two public hospitals in South Africa. Structured interviews were conducted with four MRI staff assigned to work in the 1.5 and 3.0 T MRI units. Their responses were benchmarked with ACR MR Safety guideline of 2019 to assess any safety compliance deviations. Thematic analysis was conducted by evaluating responses per themes and further expanding on comments provided on Yes or No options. There were few major shortfalls identified that include outdated safety policies, inadequate screening, nonexistence of demarcations and lack of training of MR and non-MR personnel of MRI safety. These challenges could be eliminated by introducing a comprehensive occupational health and safety program, specific to the MRI units.

Subjective symptoms of SMFs and RF energy, and risk perception among staff working with MR scanners within two public hospitals in South Africa

This study assessed subjective symptoms associated with exposure to static magnetic fields (SMFs) and radiofrequency (RF) energy, and perceived safety risk of scanners among magnetic resonance (MR) staff working in the 1.5 and 3 T MRI units. A questionnaire survey was completed by 77 clinical imaging staff working in two hospitals (A and B) in the Mangaung metropolitan region. 50 participants working with the MR scanners were regarded as exposed group and 27 participants from CT scan and X-ray departments were classified as control group. The study comprised 57% females and 43% male participants with an average MRI experience of 5.4 years. Using logistic regression, tinnitus was significantly different between various job titles (p< .034) and it was reported more often (OR 8:00; CI 1.51, 15.17) by those who worked on a 3 T scanner. Increased years of MRI experience was a significant predictor of headache (p< .05), and reporting of nausea was significantly different between various job titles (p < .01). There was an increased risks of reporting vertigo often among female participants (OR: 4.43; CI 0.91, 21.47), those with 5-15 years of MRI experience (OR: 2.09; CI 0.47, 9.34), and those with a light to moderate workload (OR: 2.70; CI 0.49, 14.86). Using linear regression, presence in zone IV during image acquisitioning was the only significant predictor for the sensation of glowing (p < .000). Movement of head/ upper body in the scanner bore was a significant predictor of nausea (p< .026), vertigo (p< .014), instability when standing (p< .014), and a metallic taste (p< .031). There was no correlation between reporting of symptoms and perceived risk of scanners. However, shift duration (r_s = 0.576), movement of head/upper body in the scanner bore (r_s = 0.424), and strength of the scanners (r_s = 0.299) were significantly correlated with perceived risk of scanners. MRI safety training and a comprehensive occupational health and safety program are necessary.

Health and safety control measures and MR quality control results in the MRI units of two public hospitals within the Mangaung metropolitan

This study aimed to identify risks and hazards in the magnetic resonance imaging (MRI) units, and assess the quality compliance of the scanners within two public hospitals in Mangaung. This is a follow-up study from a previously published study that measured static magnetic fields and radiofrequency magnetic fields in the MRI units included here. An observational checklist was used to identify risks and hazards which were later fed into a baseline risk assessment to classify and review existing control measures in the MRI units of hospitals A and B. The availability of MRI Health and Safety measures were benchmarked against the latest American College of Radiology (ACR) MRI safety requirements. The probability of risk occurrence and severity of hazards were assigned a score ranging from improbable (1) to very likely (5) and minimal (1) to irreversible effect (5). The weekly quality control test results obtained from both units were measured against the ACR quality control acceptable criteria. Similar risks were observed in both MRI units but the multiplication of probability and consequence in all risk categories resulted in a moderate risk-rating score of 12.3 for hospital A and 13.1 for hospital B. Lack of demarcation of four MRI safety zones, ferromagnetic detectors, 5-gauss line, and access control in both units scored above 15 and were classified as high risk. The defective air-cooling systems influenced the temperature of the scanner room, which affected the apparent diffusion coefficient (ADC) measurements performed from 1.5 T Siemens. On a 3.0 T Philips, a low contrast object detectability had 29 spokes for ACR T2, while the percent integral uniformity for image intensity uniformity was 78.2 %. High and moderate risks observed in both units could be reduced by the implementation of an effective health and safety programme. The ambient temperature within the scanner room should be maintained at 21 °C to attain well-performing ADC measurements and RF subsystems should be visually inspected and maintained regularly to obtain optimal image quality.