Photon absorptiometry
In medicine, photon absorptiometry is a "noninvasive method for assessing body composition. It is based on the differential absorption of x-rays (or gamma rays) by different tissues such as bone, fat and other soft tissues. The source of (x-ray or gamma ray) photon beam is generated either from radioisotopes such as 153gadolinium, 126iodine 125, or 241americium which emit gamma rays in the appropriate range; or from an x-ray tube which produces x-rays in the desired range. It is primarily used for quantitating bone mineral content, especially for the diagnosis of osteoporosis, and also in measuring bone mineralization."[1]
| Method | Source | Detection levels |
|---|---|---|
| Single-photon absorptiometry (SPA) | Isotope | Single |
| Dual-photon absorptiometry (DPA) | Isotope | Dual |
| Dual-Energy X-Ray Absorptiometry (DEXA) | X-ray | Dual |
Measurement of bone density
Bone density is generally scored by two measures, the T-score and the Z-score. Scores indicate the amount one's bone mineral density varies from the mean. Negative scores indicate lower bone density, and positive scores indicate higher.
References
- ↑ Anonymous (2024), Photon absorptiometry (English). Medical Subject Headings. U.S. National Library of Medicine.