Evaluation of photon irradiation treatment upon calcium content of ribs of Wistar rats using micro-XRF

Therapeutic doses of radiation have been shown to have deleterious consequences on bone health. Among the treatment strategies used for breast cancer treatment, the most used are radiotherapy and chemotherapy. Radiotherapy may be given to destroy the cancer cells using high-dose x-rays. Protocols vary considerably, but generally whole body irradiation totals from 10 to 15 Gy, whereas local therapy totals from 40 to 70 Gy. In clinical practice, the quantitative evaluation of bone tissue relies on measurements of bone mineral density values, which are closely associated with the risk of osteoporotic fracture. Improved survivorship rates of cancer patients receiving radiotherapy increase the importance of understanding the mechanisms and long-term effects of radiation-induced bone loss. In this work, we investigated the variation on calcium distribution in ribs of female Wistar rats (Rattus norvegicus) submitted to photon irradiation with a single dose of 20 Gy. The determination of the calcium distribution was performed using synchrotron radiation microfluorescence (SR-μXRF) at the X-ray Fluorescence beamline at Brazilian Synchrotron Light Laboratory (LNLS). Animals were irradiated using the linear accelerator Varian registered (CLINAC 2100) at the University Centre for Cancer Control of the State University of Rio de Janeiro (CUCC/UERJ). The total dose delivered was 20 Gy. The animals were about three months old and weighting about 200g. They were distributed into two groups (seven per group): control (did not receive any treatment) and irradiated (submitted to irradiation procedure) groups. Results showed that calcium content decreased within the dorsal ribs of rats submitted to radiotherapy in comparison to the control group.