[Adaptation of computed tomography and roentgenography to bone density measurements]

The increasing interest in issues connected with osteoporosis has recently caused the development of many new diagnostic methods which allow the measurement of bone density. The DEXA method, performed by specialised densitometers, is one of the most developed and reliable methods. However, the high cost od densitometers and DEXA investigation prevent this method from becoming easily accessible for everyday diagnosis. The adaptation of computerised tomography and rentgenography to densitometric measurements could be one of the methods by which the problem of densitometric diagnosis accessibility could be solved. Both methods are usually applied in the imaging of human tissues, working on the basis of differences in tissue X-ray absorption. X-ray absorption and density are related by linear function in the energy range used in rentgenography and tomography; therefore, quantitative information concerning density should be easily received. The procedure adapting computerised tomography and rentgenography to quantitative measurements of bone density in the lumbar spine is outlined in this work. The quantitative information is obtained from digitalised tomographic and rentgenographic images through use of a personal computer. Both methods were tested using a set of phantoms imitating the lumbar spine and the surrounding tissues. The precision and accuracy of both methods were assessed and compared to the precision and accuracy of the DEXA method. The outlined results confirm the usefulness of the described method in diagnosis.