전산화단층촬영에서 신체조건에 따른 자동노출과 수동노출의 차이에 대한 연구

Difference of Radiation Exposure in Computed Tomography (CT) by Anthropometric Characteristics and the Methods of Exposμre

Purpose To minimize the radiation exposure during the computed tomography (CT) examination, the practical amount of radiation exposure was reviewed in terms of anthropometric characteristics of the examinees and the methods of exposure control - automatic and manual. Materials and Methods During 5 months from March to July 2006, radiation exposure data of 200 examinees who had either chest or abdominal CT examination were collected from 16 channel slice multidetector row CT (16 slice MDCT, equipment A) and 64 channel slice multidetector row CT (64 slice MDCT, equipment B) in Hwasun Chonnam national University Hospital. Data were analyzed in relation to examinee’s body mass index (BMI), age, sex and noise index. The difference of radiation exposure between automatic and manual exposure control were also analyzed respectively Results Of total 400 examinees (267 men and 133 women), the amount of radiation exposure was significantly correlated with BMI, body weight and the noise index. The noise index was positively related with body weight. In both equipments, the automatic exposure generally showed lower radiation exposure than manual exposure. The radiation exposure in abdominal examination in e quipment A, however, showed higher radiation exposure in the automatic exposure than in the manual exposure, although statistically insignificant. The exposure levels were higher in the automatic exposure in the 82 percent of abdominal examinees for the equipment A. Conclusion Generally speaking, the automatic exposure method are superior to the manual exposure method to minimize the amount of radiation exposure during the CT examination. But this is not always the case. This study suggest that all the exposure protocol for the CT examination be reviewed through practical evaluation at the actual settings.