Length determination of long bone by CT scanogram

The CT digital radiography is a new accurate technique for measuring the long bone length. Authors performed acomparative study on accuracy, time and film consumption and radiation dose between conventional spot scanogramand CT scanogram. We used two femur and two tibia specimen for materials, the Somatom II(Siemens) for CTscanogram, and Rad Check(Voctoreen) for radiation dosimetery. There was no significant difference in accuracybetween direct measurement, conventional scanogram and CT scanogram(lesser than 1% difference). The examinationtime of conventional scanogram was about 35 minutes, CT was 15 minutes, and the film consumption of spot scanogramwas 3 of 14x17'' size, but the CT scanogram need only one 8x10'' film for completion of study. The radiation doseof hip, knee and ankle joint were 220 mRad, 365 mRad, respectively, in spot scanogram, but it was lesser than 5mRad in all joints in CT scanogram. The advantages of the CT scanogram are simple, rapid and reduced radiation.