Effective doses in pediatric chest and abdomen CT

Abstract

Background : CT is a standard imaging tool for assessing a variety of pediatric disorders. However, a major drawback of these scans is the use of ionizing radiation which potentially increases radiation-related malignancy risk. There has been no available data of pediatric radiation dose from chest and abdomen CT at KCMH.

Objective : To assess radiation dose parameters and image quality of our pediatric multi-slice chest and abdomen CT examinations, and compare them to the diagnostic reference levels (DRLs) in order to minimize or eliminate the amount of unnecessary radiation exposure.

Design : Retrospective descriptive data.

Setting : Department of Radiology, Faculty of Medicine, Chulalongkorn University.

Materials and Methods : Of the total 49 examinations of chest CT and 25 examinations of abdomen CT during Jan 2010 - June 2010, volume CT dose index (CTDI_vol), dose length product (DLP) and image noises were collected. Effective dose was accomplished by multiply adjusted DLP with region- and age-specific conversion coefficients. Third quartile values of CTDI_vol and DLP were compared to the DRLs.

Results : None of the patients aged below 5 years received CTDI_vol and DLP greater than those of the DRLs in chest and abdomen CT examinations, while, a significant number of the patients aged older than 5 years did. Thirteen out of 49 patients (27%) received CTDI_vol and DLP greater than those of the DRLs from chest CT, 8 out of 25 patients (32%) received CTDI_vol greater than that of the DRLs from whole abdomen CT and almost all of them were not performed following the department protocol. Image quality (image noise and image quality score) seemed to be greater among patients aged above 5 years in both protocols.

Conclusion : Our radiation dose parameters were within the DRLs range in patients aged below 5 years but not in those above 5 years. Being stringent to CT protocol seems to be a good solution. The percentage of the studies not done following the protocol should be solved and monitored.