Monitoring clinical exposure index and deviation index for dose optimization based on national diagnostic reference level: Focusing on general radiography of extremities.

Abstract

The International Electrotechnical Commission established the concept of the exposure index (EI), target exposure index (EIT) and deviation index (DI). Some studies have conducted to utilize the EI as a patient dose monitoring tool in the digital radiography (DR) system. To establish the appropriate clinical EIT, this study aims to introduce the diagnostic reference level (DRL) for general radiography and confirm the usefulness of clinical EI and DI. The relationship between entrance surface dose (ESD) and clinical EI is obtained by exposure under the national radiography conditions of Korea for 7 extremity examinations. The EI value when the ESD is the DRL is set as the clinical EIT, and the change of DI is then checked. The clinical EI has proportional relationship with ESD and is affected by the beam quality. When the clinical EIT is not adjusted according to the revision of DRLs, there is a difference of up to 2.03 in the DI value and may cause an evaluation error of up to 1.6 times for patient dose. If the clinical EIT is periodically managed according to the environment of medical institution, the appropriate patient dose and image exposure can be managed based on the clinical EI, EIT, and DI.