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The hardware of a new filtration device, the Microfiltrometer (MicroFM), is described. The different components of the device; impedance meter, power supply, measuring cell and its 5-micron Oligopore filter are described and it is shown how they are interrelated and interfaced to a computer for data acquisition. The properties of the filter and the general functioning principle of the device are also elucidated. For each run, the MicroFM generates elementary signals from individual passages of many hundreds of red blood cells (RBCs) through micropores of a given 5-micron Oligopore filter. Analysis of each elementary signal provides two complementary parameters, the transit time tau of the explored RBC and the change in electrical impedance deltaZ caused by the temporary flow of the considered RBC through a particular micropore of the filter. These two parameters can be utilized for reliable assessment of erythrocyte deformability on a cellular level.

Dosimetric monitoring is useful to limit exposures to ionising radiation in medical occupational settings, and reduce subsequent health risks. Scientific literatures, such as the UNSCEAR report 2017 and International Atomic Energy Agency Report 2014b, updated information on this subject; however, few African works have been found. This is the reason why we undertook this study, which summarises existing information on monitoring external radiation exposure doses for the whole body, using data from medical workers on this continent. Using standard terms and combining different keyword searches for radiation dose monitoring among radiology healthcare workers in Africa, from the titles, abstracts, and full texts, we found 3139 articles in the PubMed/MEDLINE, Google Scholar and INIS databases. Two reviewers screened the retrieved publications based on predefined eligibility criteria to identify relevant studies, extract key information from each, and summarise the data in table form. A total of 20 potentially relevant articles were identified. Among these 20 articles, 15 reported the overall average annual effective dose. Studies included in this systematic review represent an inventory of the radiation protection of medical workers in various African countries, with a focus on the monitoring of occupational radiation exposure. The size of studied populations ranged between 81 and 5152 occupational exposed workers. The mean annual effective doses ranged from 0.44 to 8.20 mSv in all specialities of medical sectors, while diagnostic radiology ranged from 0.07 to 4.37 mSv. For the nuclear medicine and radiotherapy from medical groups, the mean annual effective dose varied between 0.56 and 6.30 mSv. Industrial and research/teaching sectors data varied between 0.38 to 19.40 mSv. In conclusion, more studies implemented on dosimetric monitoring in Africa are needed to get a real picture of occupational exposure in the continent.

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The Microfiltrometer consists of a filtration system for diluted erythrocyte suspensions, through a filter containing 30 cylindrical micropores, 5 microm in diameter, under the influence of a driving pressure. A feeding sinusoidal alternating current of 40 kHz, 300 microA is delivered to the filter. The change in impedance is collected for each temporary flow of erythrocytes through a given micropore. Two main parameters are measured for individually explored erythrocytes: the entry time tau in the micropore and the maximal variation of impedance deltaZ occurring for the transitory flow. The slope deltaZ/tau defines the velocity of pore blockage. A "Microfiltrometer Deformability Index" (MDI) is established by using this slope. When MDI > or = 1, the erythrocyte is considered to be deformable and, conversely, when MDI < 1, the erythrocyte is considered to be undeformable. Using this procedure, less than 2% undeformable erythrocytes in healthy blood samples are identified, with a specificity of 99% and a sensitivity of 97.5%.