[Examination about the Direction for Uses of the Radiation Exposure Reduction Mechanism (Organ Effective Modulation) in Consideration of Organ Sensitivity].

Automatic exposure control technology can reduce the radiation dose during CT. The purpose of this study is to reveal the important points regarding the usage of organ effective modulation (OEM), by evaluating the characteristics of OEM, an automatic exposure control technology. An analysis of the dosage profiles revealed that OEM may not work with the first rotation of the X-ray tube in the helical method and wide volume method. This phenomenon can be avoided by using the orbital synchronism helical method. This was also demonstrated upon measurement of the integrated absorption dose at the imaging start position. An analysis of standard deviation measurement revealed that with the combined use of OEM and x-y modulation, the reduction in dose may significantly vary depending on the presence or absence of the gantry tilt. Based on the above results, when using OEM to reduce the dose at the imaging start position, the combined use of x-y modulation should be avoided and the orbital synchronism helical method should be used.