International radio frequency (RF) electromagnetic field (EMF) exposure assessment standards and regulatory bodies have developed methods and specified requirements to assess the actual maximum RF EMF exposure from radio base stations enabling massive multiple-input multiple-output (MIMO) and beamforming. Such techniques are based on the applications of power reduction factors (PRFs), which lead to more realistic, albeit conservative, exposure assessments. In this study, the actual maximum EMF exposure and the corresponding PRFs are computed for a millimeter-wave radio base station array antenna. The computed incident power densities based on near-field and far-field approaches are derived using a Monte Carlo analysis. The results show that the actual maximum exposure is well below the theoretical maximum, and the PRFs similar to those applicable for massive MIMO radio base stations operating below 6 GHz are also applicable for millimeter-wave frequencies. Despite the very low power levels that currently characterize millimeter-wave radio base stations, using the far-field approach can also guarantee the conservativeness of the PRFs used to assess the actual maximum exposure close to the antenna.

In March 2020, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) released its new guidelines (ICNIRP 2020) on the limitation of radio frequency (RF) electromagnetic fields (EMF) exposure in the frequency range 100 kHz–300 GHz. These have taken several years to develop and include the review of the latest scientific literature. Most countries worldwide currently apply the RF-EMF exposure limits provided in the ICNIRP 1998 guidelines and are expected to align their regulations according to the recently revised limits. In this paper, the implications of the ICNIRP 2020 guidelines on the RF-EMF compliance of base stations (BSs) for mobile communications are analyzed in detail. The study covers different types of BS products, from low-power small cells to macro cell equipment, operating within different frequency bands and of relevance for 2G to 5G mobile technologies. A direct comparison of the BS RF-EMF exclusion zones (or compliance boundaries), when the ICNIRP 2020 and the ICNIRP 1998 limits are applied, is provided. Since existing and future mobile equipment infrastructure is likely to be required to comply with the ICNIRP 2020 guidelines, the paper provides useful information to mobile equipment manufacturers, mobile operators, standardization bodies and regulators.

6073 Background: Existing patient recall systems usually involve contacting the referring physician who then notifies the patient to schedule a return visit for further imaging. We set out to determine whether a direct patient callback system would improve patient compliance in returning for additional imaging including magnification, spot compression, and ultrasound, and whether that would translate to an improvement in early breast cancer detection. Methods: Beginning on 4/1/2004, we prospectively identified all patients whose screening mammograms were read as having an incomplete assessment that required additional imaging (ACR BIRADS 0). Those patients were contacted directly via telephone to return for additional views. Results: Between 11/1/2002 and 3/31/3004, 1142 patients with incomplete screening mammography were identified and the referring physicians were contacted. 956 of 1142 (84%) patients returned and underwent additional breast imaging. Between 4/1/2004 and 12/31/2005, 1,336 patients with incomplete screening mammography were contacted directly to return for additional imaging. 1,307 of 1,336 (98%) patients returned and underwent additional breast imaging. (p < 0.0001, Fisher’s exact test). 125 of the 1,307 (8.5%) of the subsequent exams were found to be suspicious and biopsy was recommended (ACR BIRADS 4 or 5). Conclusions: Our new system of contacting patients with incomplete mammography has significantly increased our recall rate. Implementation of this system has enabled us to identify those patients whose mammograms are suspicious and ultimately diagnose breast cancer earlier. Direct patient callback has become standard policy and we are recommending this system for all radiology recall examinations. No significant financial relationships to disclose.