Quantitative investigation of the x-ray absorption coefficient in computed tomography. An approach to numerical diagnosis.

From printout data of 50 normal and 50 abnormal scans of a brain slice picking up the basal ganglia the numerical values of SD and DC were obtained and those values lying inside M + 2sigma were arbitrarily regarded as normal. By these criteria two cases (4%) were diagnosed as false negative and three cases (6%) as false positive, with a misdiagnosis rate of 5%.