A review of MRI studies in Africa with special focus on quantitative MRI: Historical development, current status and the role of medical physicists.

This scoping review provides overview on the historical and major developments, current status, quantitative magnetic resonance (MR) studies and the role of medical physics bodies in MR imaging in Africa. The study analyzed MRI availability in 32 (59 %) of the 54 African countries. South Africa and Egypt have the most dominant MR systems. Number of MR systems in the 4 northern countries (Egypt, Morocco, Algeria and Libya) alone constitute 53 % of the total number of machines in the studied countries. Less than one-third of the countries have 1 MR system serving less than a million population. Libya recorded the most MR systems per million population. The studied countries altogether have an average of 1 machine per million population. The private sector far dominates number of installed MR systems across the region, making up two-thirds of the distribution. A major challenge was revealed where less than 3 % of Medical Physicists in the studied countries are engaged in MRI facilities. Review of MRI published studies in the last 5 years indicates dominance of literature on brain studies and most of such published works coming from Nigeria. Only 7 out of 27 published studies reviewed were quantitative. The African region has no dedicated MRI physics societies; however, the regional medical physics body and national associations have big roles to play in developing MRI through education, research, training and leveraging on awareness creation. Thisreview is the first of such wide scale study on MRI availability and quantitative studies in the African region.

Biological Evaluation of Grid versus 3D Conformal Radiotherapy in Bulky Head and Neck Cancer.

Grid radiotherapy is one of the treatment techniques applied to treat patients with advanced bulky tumors. Purpose: This study aims to estimate the difference in biological and dosimetric parameters of the grid radiotherapy technique for the treatment of bulky head and neck (H and N) tumors and compare it with conventional conformal radiotherapy. Subjects and Methods: Three-dimensional conformal and grid radiotherapy were designed by the Monaco treatment planning system (TPS). Eight bulky tumors of (H and N) cases were selected, using a single fraction 15-20 Gy. Dose-volume histogram of the tumors and organs at risk (OARs) used to calculate the equivalent uniform dose (EUD) (Gy) by Matlab program. Furthermore, dosimetric parameters of the tumors from the TPS were compared for two techniques (grid radiotherapy and the conventional conformal radiotherapy). Results: Grid attained a lower EUD (Gy) in tumors and OARs as compared to conformal therapy, as Grid principle protects about half of the tumor area from the radiation leads to less coverage of the tumor. Also, where OARs in closed with tumors and the shielding by multi-leaf (1 cm) were more effective than other techniques, lead to a decrease of radiobiological values according to its definition by Niemierko. Radiobiological results showed significant differences between the two methods, and dosimetric data obtained by the TPS for tumours for two plans were P < 0.05. Conclusions: The grid plan achieves lower values of EUDs than the conformal technique for OARs. Hence, it achieves more sparing and fewer complications for these organs.