RESUMO
Objective To calculate the chest volume for an evaluation of lung development ,the degree of thorax narrowing and pectus excavatum deformity by the surface measurements .Methods Ninety normal Sprague Dawley (4 weeks) rats were ran‐domly divided into experimental and control groups .Experimental group had 70 rats and control group had 20 rats .Cutting off the lower three cartilage from parasternal of rats to produce Pectus excavatum model in experimental groups .We measured many chest radial lines before surgery ,2 ,4 ,8 and 12 weeks after surgery respectively ,then made comparison between parallel group .Thoracic volume size was calculated by a mathematical formula ,Archimedes measurement and the CT three dimensional reconstruction ,and the t test and linear regression were analyzed by SPSS17 .0 .Results this experiment used multiple radial lines to get measurement results ,and through mathematical calculations ,Archimedes measurement and CT reconstruction ,we found there were significant differences between the experimental group and the control group (P<0 .05) .Conclusion It is practicable of surface measurement to calculate chest volume .This method could replace the CT examination to evaluate the change of the chest volume along the process of pectus excavatum formation .