Roentgen diagnosis of sex based on adult skull characteristics; comparison study of cephalometry of male and female skull films (frontal pro-projection).

Abstract

ASURVEY OF THE medical literature indicates that there has been no attempt to compare definitively skull radiographs of the male and female adult. Keen (1) has presented this problem from the standpoint of the anthropologist and it was felt that a comprehensive evaluation of the roentgenology would be of value and interest. It was also felt that such a study might be of some importance medicolegally. We have been encouraged by a personal communication (2) to develop this comparison. Methods The basis for this paper was the evaluation of 100 normal adult male and 100 normal adult female skull films. The ages of the male patients ranged from twenty to seventy-two years and the females from twenty-two to eighty-six years. The films were compared with regard to the following characteristics noted on the frontal projection (posteroanterior): 1. Sagittal diameter: Measurement of the distance from the top of the skull in the midline to the lower edge of the mandible in the same plane. 2. Mastoid length: Measurement of the distance from the inferior tip of the mastoid process to the petrous ridge perpendicularly above the mastoid tip. 3. Mandible width: Measurement of the distance from one lateral border of the mandible to the other similar border at the level of the mastoid tip. 4. Mandible angle width: Measurement of the width of the mandible at the angle, this being the distance from the outer to the inner margins. Figure 1 shows the points at which the measurements were obtained. Only films made with the mouth closed were included. The distance from the tube to the film was 36 inches, and the central ray was either straight (perpendicular) or angulated 100 toward the feet. In evaluating the results, an attempt has been made to predict the sex of the patient, thereby testing the validity of identification of male and female skulls by the measurements used. Results The results of the measurements of the diameters listed above are portrayed graphically in Tables I-IV. The ordinate line represents the number of cases and the abscissa line the measurement in centimeters in all cases. The left side of each table includes the female cases and the right side represents the males. In the center of each table there is an area which includes those cases in which the measurements are similar for the sexes. We have termed this area of overlapping the “neutral zone.” Table I presents the data comparing the sagittal diameters. If we accept the limits of the diameter from 21.0 to 24.4 cm., the diagnosis of female by this measurement is 91 per cent accurate. The “neutral zone,” where the upper diameters of the female skull and the lower diameters of the male skull overlap, is from 24.5 to 25.4 em.