Osteodensitometry of vertebral metastases after radiotherapy using quantitative computed tomography

Bone density has been assessed during and after radiotherapy of metastases of the spine using quantitative computed tomography (QCT) in 19 patients with osteolytic vertebral lesions. All patients underwent external photon radiation with a total dose of 40 Gy over a period of 4 weeks. Measurements of vertebral mineral density were performed at the beginning, at the end, and 3 months after radiotherapy. In 13 patients with osteolytic metastases, radiotherapy achieved complete release of pain; it was unsuccessful in the remaining 6 patients. Immediately after successful radiotherapy, osteolytic metastases showed a decrease of bone density of 24.7% followed by an increase of 60.6% 3 months later. Normal bone surrounding the osteolysis showed an increase of density at the end and 3 months after radiotherapy. QCT has proved to be a helpful tool in assessing successful radiotherapy of metastases of the spine.