Erratum

Abstract

In a paper entitled “Patient doses from computed tomography in Manitoba from 1977 to 1987” by W. Huda et al (1989), there is an error in equation 2 on page 140. The revised equation 2 should read This change (i.e. replacing the slice thickness T by the slice thickness squared T2) requires modification of the resultant Tables V, VI and VII. The modified Table V should now read The corrections for Table VI are only for the years 1984 to 1987. In these years, the collective effective dose equivalent has been overestimated by factors which range from 10% to 30%. The (approximate) corrections for these years are given below. 1984 10% reduction in the collective dose (person-Sv) 1985 15% reduction in the collective dose (person-Sv) 1986 15% reduction in the collective dose (person-Sv) 1987 30% reduction in the collective dose (person-Sv) In Table VII, the computed average HE values for patients undergoing CT scans in Manitoba are obtained using the collective dose values given in Table VI. Thus the values of average patient HE for the years 1984 through 1987 should be reduced by the same amount as the collective doses in Table VI. In addition, in Table VII the correct scanner specific patient HE values should now read: Average patient HE for the GE scanner (1987) 3.1 mSv Average patient HE for the Siemens DRH 3.4 mSv