[Possibilities for dose reduction in coronal spiral CT of the mid-face area]

The radiation dose at the eye lens and the thyroid gland in spiral-CT-examinations is comparable to those known from conventional computed tomography. In view of an increasing artificial radiation exposure, it remains an important aim to achieve dose reduction with persistent adequate imaging quality. We determined the doses of the named organs in four different CT-examination protocols by use of phantom studies and in 45 patients. By reduction of tube current and tube voltage, organ doses can be reduced by half. This is achieved without a relevant loss in diagnostic precision as far as high-contrast structures are concerned. Compared to conventional CT-scanning, the dose reduction reached 75%. Taking into consideration the increasing insensitivity in the z-plane and the worsening of the section-sensitivity profile, a properly chosen increase in pitch may result in a significant dose reduction. CT-scanning of high-contrast structures in the head and neck can and should be performed with the least radiation exposure possible.