Dosage measurement in spiral CT examinations in the head and neck region

Purpose: In view of the increasing frequency of computed tomographic examinations the organ doses of the thyroid gland and the eye lenses in spiral CT examinations of the head and neck should be determined. Material and methods: Standard CT-examinations of the neck, the paranasal sinuses in axial and coronal sections, and the mandibula were simulated by help of an Anderson-Rando phantom. Dose measurements were performed as well in 28 patients. The examinations were carried out in spiral mode ("Somatom AR.SP" "Picker PQ 2000", and "Toshiba Xpress SX") and conventional single slice technique ("Somatom Plus"). Three LiF-TLD were placed on each eyelid and three on the thyroid. Results: With direct exposure to the x-ray-beam the organ doses did not exceed 64 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 data known from conventional CT.