Measurement of Absorbed Dose in the Air in X-ray CT Examination Rooms Using a Special Protective Shield for CT

Abstract

Purpose: X-ray CT examinations are required not only in routine medical examinations but also in various situations such as emergency medical care. Although medical staff may be exposed to radiation when assisting patients, the distribution of air-absorbed doses in the CT examination room when using a special protective shield for CT has not been clarified. Here, we measured air-absorbed doses at several points simultaneously to clarify the distribution of these doses and the effect of a special protective shield for CT in reducing them. Method: A human phantom was imaged with an X-ray CT system. The absorbed dose in the air dose profile distribution was measured with an OSL dosimeter in the presence and absence of a special protective shield for CT. Results: The highest air absorbed doses of 4.27 mGy were at 0 cm in the horizontal direction, 120 cm in the vertical direction, and 50 cm in the body axis direction. The largest reduction in air absorbed dose following installation of the special protective shield for CT was 91.7%, obtained at 0 cm in the horizontal direction, 150 cm in the vertical direction, and 50 cm in the body axis direction. Conclusion: A 91.7% reduction in air-absorbed dose was o directly behind the special protective shield for CT. The reduction in air-absorbed dose was 65.8% at the location of a gap between the special protective shield for CT and gantry.