Investigation on the relationship between the measured dose vs. the displayed dose in CT examinations for children / 中国医学装备

ABSTRACT

Objective: To establish the relationship between the measured dose and the displayed dose in CT scans for children, and assess whether the displayed dose could be used as the basis to monitor the actual dose so as to provide data support for establishing a fast estimation method of actual dose in CT examination for children. Methods: The CT equipments with 16 slices detectors and 64 slices detectors of two manufacturers that often were used in clinical practice were selected in the research. CT dosage phantom that suited to children was used and pencil-ionization chamber was adopted to measure CT dose indexes of head scan and breast scan for children under various scan parameters. At the same time, displayed dose of the equipment was recorded and the ratio of measured dose and displayed dose was calculated . Results: The measured doses of the two manufacturers for head of children were 1.30-1.39 times and 1.17-1.26 times of displayed dose, respectively. And on thorax sequence, the measured doses were 1.95-2.27 times and 1.75-1.97 times of displayed dose, respectively. Based on above results, the measured dose of head was more close to the displayed dose than that of thorax sequence. Conclusion: In the CT examination of children, the ratio of measured dose to displayed dose shows good consistency under the different exposure conditions of same CT device model, and thus provides possibility to rapidly estimate the real dose on children according to the displayed dose in CT examinations.