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An in-situ measurement of the background radiation level was carried out at the vicinity of three campuses of two major tertiary institutions in Minna. A portable Geiger-Mueller tube-based environmental radiation dosimeter was used for the measurement. A total of 34 point was surveyed across the three institutions for background environmental radiation. The dose rate range obtained are: at the Niger State College of Education Minna (NCM), the dose rate varies from 0.125 µSv/hr to 0.171µSv/hr; at the Federal University of Technology Bosso Campus (FUTB) it wass between 0.152 µSv/hr and 0.184 µSv/hr; and at the Federal University of Technology GidanKwano campus FUTG it was between 0.137 µSv/hr and 0.184 µSv/hr. In all the 34 points surveyed the mean dose rate was 0.154 µSv/hr with a standard deviation of 0.017 µSv/hr. Generally, the dose rate level in each of the institutions surveyed are comparable to one another and could simply be attributed to natural sources. The average annual effective dose obtained from this study is 0.189 mSv/annum which is still less than the recommended limit of 1mSv/annum by International Commission on Radiation Protection [ICRP] for non occupational population exposure. @ JASEM Radiation from many sources is omnipresent on the earth surface, consequently man is continuously irradiated. The basic difference between ionizing (nuclear) radiation and other common types of radiation in the environment such as heat is that it possesses sufficient energy to cause ionization. In water of which cell are largely composed, ionization can lead to molecular changes and to the formation of chemical species of a type which are damaging to the chromosome material. Ionizing radiation injury is dependent on a number of factors including: The nature (alpha (α), betta (β), and gamma (γ)) and energy of the radiation, the dose, time of exposure, homogeneity of dose and shielding. When the dose and dose rate is within the accepted level, the effect of radiation is small and most time no effect is noticed, although the effect of low level radiation are not yet completely understood

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This research presents a new Windows compatible program (EXABCal) for photon exposure and energy absorption buildup factors for standard energy grid from 0.015- 15 MeV for elements, mixtures and compound. This program was written using Python programming language and the calculation of buildup factors was based on the well-known Geometric Progression (GP) fitting procedure. The equivalent atomic numbers and GP fitting parameters of mixtures and compounds can also be evaluated using this program. The program has been used to evaluate the photon exposure and energy absorption buildup factors for standard energy grid from 0.015- 15 MeV for water, air and concrete, compared with values from the American Nuclear Society (ANS) standard reference data (ANSI-6.4.3) and found to be of high accurate with minimal errors. The program is fast and easy to use and will be of valuable interest to medical Physicist, radiation Physicists, Radiation shielding design engineers, students, teachers and researchers and other experts working in areas where nuclear radiation is applied.

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In this study, organ and conceptus doses of patients undergoing chest, abdomen and skull radiograph examinations at two Nigeria X-ray centres, Niger State General Hospital (NGH) and Two-Tees (TTX), are reported. Air kerma was measured, and entrance surface dose (ESD) and half-value layer estimated for each set of tube potential (kV(p)), focus to skin distance and current-time product (mAs) used for each of the patients included in this study. Results show that the mean air kerma in the two centres are similar for the three projections considered in this study. Organ doses ranged from <0.01 to 2.18 mGy in NGH and from <0.01 to 1.29 mGy in TTX for examinations of the abdomen, from <0.01 to 0.20 mGy in NGH and from <0.01 to 0.13 mGy in TTX for examinations of the skull and from <0.01 to 3.90 mGy in NGH and from <0.01 to 1.96 mGy in TTX for examinations of the chest. Generally, no significant difference is seen between the organ doses of male and female patients. In NGH, organ doses are generally greater than those from TTX for the three examinations. The mean ESDs for examinations of the chest postero-anterior, abdomen antero-posterior (AP) and skull AP are, respectively, 5.37, 6.28 and 4.24 mGy in NGH, and 5.82, 5.33 and 4.76 mGy in TTX. The ESDs reported in this study, except for examinations of the chest, are generally lower than comparable values published in the literature. Conceptus doses were also estimated for female patients using normalised published conceptus dose data for abdomen examinations. The estimated conceptus doses were >1 mGy even when the conceptus was located 12 cm below the surface of the abdomen.