| Summary: | 碩士 === 中山醫學大學 === 生物醫學科學學系碩士班 === 104 === Purpose
In the past other studies we found changes in body thickness will have an impact to bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DXA). But those studies subjects are all older adult, the effect of body thickness in child still not clear.
Materials and Methods
This study we simulated body fat by bolus to observe the effect of fat layering on BMD measurements in 5 y/o , 10 y/o and adult phantom by fan and pencil beam DXA. Also we measured effective dose by Thermolummescent detectors (TLD) to observe the different of fan and pencil beam DXA.
Results
In pencil beam DXA, associations between body fat thickness and BMD is 0.8554(5y/o) , 0.2543(10y/o) and 0.9596(adult). In fan beam DXA, associations between body fat thickness and BMD is 0.1535 (5y/o) , 0.6341 (10y/o) and 0.9641 (adult). The fan beam DXA BMD measurement effective dose were higher than pencil beam(effective dose: 26.23vs14.79μSv(5y/o) , 14.89 vs 6.93 μSv(10y/o) and 45.97 vs 6.12(adult)).
Conclusion
Pencil and fan beam DXA BMD measurement both affected by body thickness change. Pencil beam DXA had smaller effect by body thickness change in both phantom. Effective dose from pencil and fan beam DXA can not separate from natural background radiation, but fan beam had higher effective dose than pencil beam.
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