The aim of the study was to radiographically monitor the early effect of radiotherapy in conjunction with Disodium Pamidronate (DP), on metastatic bone disease, using image-processing techniques. Eight patients with bone lytic metastasis received radiotherapy with a 6MV linac up to a dose of 30Gy (3Gy per fraction, 5 days a week) combined with 6 monthly sessions of infusional 180mgr of DP. Conventional X-rays of all patients were obtained at every session of the treatment, retaining the same settings for each exposure. Quality assurance of accuracy and precision of X-ray exposure parameters showed acceptable values. The analysis of the image attributes was based on measuring the first order statistics of the gray level histogram such as mean value (MVGLH) and energy (EGLH), in 24 small rectangular areas constituting the region of lytic metastasis. The measurements showed a 35.72 % reduction of EGLH and a 3.17% increase of MVGLH, before and after the combined treatment. Further analysis concerning the measurement of the optical density of the film in the region of lytic metastases at every session of the treatment revealed a reduction up to 29.12% (P < 0.001, Kruskal-Wallis test). The changes in the MVGLH were high correlated with the changes of EGLH in terms of Rs = 0.98 (P < 0.0001, spearman’s-rho test) and furthermore with the changes in optical density in terms of Rs = 0.87 (P < 0.0001, spearman’s-rho test). These findings indicate a significant level of reliability for both of the above-mentioned methods and beyond this, an important objective early increase in bone mass and formation, which was difficult to be identified visually by the experts.