DOSAGE MEASUREMENT IN SPIRAL CT EXAMINATI ONS IN THE HEAD AND NECK REGION

Purpose: In view of the increasing frequency of computed tomographic e xaminations the organ doses of the thyroid gland and the eye lenses in spiral CT examinations of the head and neck should be determined. Mat erial and methods: Standard CT-examinations of the neck, the paranasal sinuses in axial and coronal sections, and the mandibula were simulat ed by help of an Anderson-Rando phantom. Dose measurements were perfor med as well in 28 patients. The examinations were carried out in spira l mode (''Somatom AR.SP'' ''Picker PQ 2000'', and ''Toshiba Xpress SX' ') and conventional single slice technique (''Somatom Plus''). Three L iF-TLD were placed on each eyelid and three on the thyroid. Results: W ith direct exposure to the x-ray-beam the organ doses did not exceed 6 4 mGy. When exposed by scatter radiation only, doses may be reduced by a factor of up to 10. The measurements in 28 patients showed similar results. Conclusions: The organ doses in spiral CT correspond with dat a known from conventional CT.