Three principles should be followed when choosing the measurement method of bone mineral density: (1) Clarify the significance of measurement; (2) Estimating the degree of osteoporosis; (3) Evaluate whether the treatment is effective.
1. 1 neutron activation analysis (NNA)
Active radioactivity 49Ca. Then, the high-energy rays emitted by 49Ca are immediately measured with a high-resolution Ge (Cr) detector. Calculate the original stable nuclide content by formula. NNA method can be used to measure the bone mineral density of human hand bones, spine and trunk, and can also be used to measure the calcium content of the whole body. Disadvantages: high cost and large radiation.
1.2 quantitative CT (QCT)
Based on the imaging principle of XCT, that is, different absorption of X-rays by human tissues leads to X-photon attenuation, the tissue density of any part can be calculated. Disadvantages: high price, large radiation dose and low accuracy.
1.3 photon scattering method
When rays or X-rays interact with matter, part of the radiation energy radiates to electrons outside the nucleus of matter, resulting in Compton electrons, and the photon energy weakens and the direction changes. Disadvantages: the radiation is large and it is impossible to measure the axial bone.
1.4 x-ray beam method
X-ray beam method is a method to calculate bone mineral density according to the tissue absorption rate of X-ray beam irradiated by clusters. Disadvantages: the measuring range is small and special equipment is needed.
1.5 ultrasonic method
The method of measuring bone density and bone mass by ultrasonic principle and evaluating bone density by broadband ultrasonic attenuation signal. Ultrasonic technology can not only measure bone density, but also reflect bone strength and bone structure. It has the advantages of convenient detection, no radioactivity, low price, easy movement and general survey. It can not only detect osteopenia and bone loss, but also be suitable for children, pregnant women and lactating women. Kangyu medical bone mineral density analyzer adopts ultrasonic detection principle. By detecting people of different age groups and referring to the perfect databases of different regions and different age groups, the bone content was comprehensively analyzed and the bone health status was evaluated. Through the analysis, individual physical development evaluation, bone mineral density analysis, dietary intake analysis and food exchange guidance were carried out to provide a guiding scheme for improving dietary nutrition therapy.