Diagnostic Reference Level for Computed Tomography Thorax Examination: A Single Centre Study
Keywords:CT thorax, CT dose index, diagnostic reference level, dose length product, effective dose
The increased number of CT Thorax examinations has shown an increase in frequency of patients exposed to medical radiation. Therefore, the recent radiation exposure from CT thorax should be revised to achieve dose optimization. This study is aimed to determine a local diagnostic reference level (DRL) in CT thorax study. Data on CT thorax cases (n=307) were retrieved retrospectively from the Picture Archiving Communication System (PACS). Data input including CT scanner model, manufacturer and scanning parameters were incorporated in the CT-EXPO software. Weighted CT dose index (CTDIw), volume CT dose index (CTDIvol), dose length product (DLP) and effective dose (E) were automatically generated from the input. The data was presented as 75th percentile and compared with the previous established national DRL report from the Ministry of Health Malaysia. The results demonstrated DRLs of CTDIw, DLP and E are notably lower than the established national DRLs (8.05 mGy vs 21.30 mGy, 392.31 mGy.cm vs 415mGy.cm and 5.39 mSv vs 8.00 mSv, respectively). The present DRL of CT thorax is lower than the established national DRL report. The present data on the dose reference level could contribute as a guideline for dose optimization in CT thorax examination.