Crosshole radar measurements were taken in 4 vertical boreholes aligned on a N-S profile. During the survey, the receiver was kept in one borehole at the extremity of the profile while the transmitter was moved along the 3 other boreholes. Using this overlapping survey geometry, several first arrival amplitudes at different transmission distances were measured for specific raypath angles. These amplitudes depend on the traveled distances and raypath angles. Several factors, such as the antenna radiation pattern, partitioning of energy at interfaces, and anisotropy of the media, explain the variations of the first arrival amplitudes with raypath angles. The antenna radiation pattern and anisotropy can be taken into account prior to, or during tomographic procedures. However, effects from partitioning at interfaces and residual amplitudes from the theoretical antenna radiation function used in data reduction, may be misleadingly introduced into a tomographic algorithm. Owing to the overlapping geometry, a correction combining these 2 factors is statistically estimated and applied to the data. The direct arrival attenuation tomograms obtained from the corrected data are more representative of the local geology.