Otimização da tecnica de densitometria optica em imagens radiograficas de peças osseas : estudo "in vitro"

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

This experiment was designed in order to determine the sensibility and precision of radiographic optical densitometry by the characteristic curves setorization of radiographics films. We used the mathematic expression describted by PELÁ et aI. (1990), a special computer software (PELÁ et aI., 1992) adapted for to this analysis and the correction of X radiation not uniformity effects. In the first part of this study, twenty pieces of chicken bone and twenty pieces of ox bone, 4,5 cm and 1.5 cm long, respectively, were radiographied by the conventional technique. An eighteen stepped aluminium wedge was used as a densitometric reference. The bones pieces were divided into groups to be descalcified for 2. 4, 7 and 9 days (chicken) and 7. 14. 21 and 28 days (ox). in order to correlate bone mass loss with bone density (values measured in mmAI). Quantification of bone mass loss in each group was done by the titulation technique, after calcination. Linear correlation was high (r>0,97; p <0.02) for the mean values of mmAI. We also observed an excelent correlation between bone mass loss and calcium loss (r = 0,96; P = 0.007) in ox bone. In the second part of the experiment 64 bone pieces of dog (diaphysis of tibia), 1.2 cm long, were observed during the descalcifjcation process and the mineral loss was determined by quantifyng the dried bone mass with a precision balance. To evaluate the X-ray dispersion effect we used two aluminium plates (3 mm wide) beside the stepped wedge. The bone pieces ~ were analysed in shorter periods of descalcification (6, 12, 18, 24, 36 and 48 hours), and the sensibility of this methodology was determined. Correlation for this group (dog bone) was greater than that one observed for the chicken and ox bones (r>0,97 for 68.19% of the analysed pieces)

ASSUNTO(S)

radiografia

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