Abstract
A photon scattering method for measuring the trabecular bone mineral density (TBMD) in vitro is described. This method involves the measurement of the ratio of coherent to Compton 90° scattered photons from Am–241 by using a narrow beam geometry with an intrinsic germanium detector. The feasibility of using smaller scattering angles for better counting efficiency and the associated problems in their application for in�vivo measurements were investigated. Calibration of the system with fresh trabecular bone samples showed a linear relationship between the coherent to Compton ratio R of the detected counts and the TBMD (r = 0.94). The effect of the overlying soft tissue on the R ratio was significant while the effect of self�attenuation by the trabecular bone itself and the cortical layer was negligible. It was found that the marrow fat content could alter the value of the R ratio. Our results show that for a 10% increase in the fat content in the interstices of the trabecular bone there is a 2.5% decrease in the R ratio. This technique together with soft tissue corrections will enable us to measure the TBMD of the calcaneum in vivo, assuming a small variation in the trabecular fat content. The estimated absorbed dose to the bone marrow is about 139 mrad.
Original language | English (US) |
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Pages (from-to) | 208-215 |
Number of pages | 8 |
Journal | Medical physics |
Volume | 9 |
Issue number | 2 |
DOIs | |
State | Published - Mar 1982 |
Externally published | Yes |
Keywords
- AMERICIUM 241
- ANGULAR DISTRIBUTION
- CALIBRATION
- COHERENT SCATTERING
- COMPTON EFFECT
- DENSITY
- EFFICIENCY
- IN VITRO
- MEASURING METHODS
- MINERALIZATION
- TRABECULAR BONE
ASJC Scopus subject areas
- Biophysics
- Radiology Nuclear Medicine and imaging