en Medical Physics Medical Physics تحقيق بديع Original Research <div style="text-align: justify;">Background: Assessment of activity concentrations of ²³⁸U, ²³²Th, ⁴⁰K and gamma dose rate (DR) was carried out over a laterite mining field in Ilorin-south, Nigeria. Materials and Methods: A well calibrated Super-Spec (RS-125) gamma spectrometer was used to measure the activity concentrations of ⁴⁰K, ²³⁸U, ²³²Th and gamma doses rate at 1 m above the ground level over the laterite mining field. Fifty (50) measurements of the activity concentration of the radionuclides were obtained at about 1 meter above the topsoil. For each point, measurements were taken four (4) times for better accuracy. Results: The overall mean of the activity concentrations of ⁴⁰K, ²³⁸U and ²³²Th are 81.38, 43.89 and 38.79 Bqkg^-1respectively. The mean value for DR was found to be 46.44 nGyhr^-1. The mean activity concentrations of ²³⁸U and ²³²Th are higher than the recommended limits provided by UNSCEAR. This is a cause for worry as significant enhancement in the concentration of ²³⁸U and ²³²Th will increase the level of the background radiation and possibly render the soil unfit for use in building and construction. The results of most of the radiological impact parameters (RIP) are above the limits provided by UNSCEAR. Conclusion: From the results, it implies that the risk of indoor gamma radiation exposure is high for this lateritic soil. So the lateritic soil from this mine field may not be too suitable for building and construction purposes.</div> Radioactivity, background radiation, gamma spectrometry, radiological impact parameters, Ilorin. 895 906 http://ijrr.com/browse.php?a_code=A-10-2055-76&slc_lang=en&sid=1 M.M. Orosun muyiwaorosun@yahoo.com 7900319475328460017132 7900319475328460017132 Yes Department of Physics, University of Ilorin, Ilorin, Kwara state, Nigeria M.R. Usikalu 7900319475328460017133 7900319475328460017133 No Department of Physics, Covenant University, Ota, Ogun State, Nigeria K.J. Oyewumi 7900319475328460017134 7900319475328460017134 No Department of Physics, University of Ilorin, Ilorin, Kwara state, Nigeria