Room: Exhibit Hall | Forum 9
Purpose: Aim of this study is to measure radiation doses, for selected CT examinations from 67 CT departments in Tamil Nadu region from QA controlled CT machines as a first step to help the regulatory body in the country to establish national CT DRLs.
Methods: A pilot study investigated the most frequent CT examinations. 67 CT sites were asked to complete a questionnaire to enable the recording of CT exposure parameters for head, chest and abdomen procedures during a 1 year time period. Dose data such Volumetric Computed Tomography Dose Index (CTDIv) and Dose length product (DLP) on a minimum of 50 average-sized patients in each category were recorded to calculate a mean site CTDIvol and DLP value. The rounded 75th percentile was used to calculate a DRL for each site and the region by compiling all results. Results are compared with international DRL data.
Results: Data were collected for 10,050 patients. DRLs are proposed using CTDIvol (mGy) and DLP (mGy.cm) for CT head (48 and 994 respectively), CT chest (12 and 497 respectively), and CT abdomen (14 and 630 respectively). These values are lower than current DRLs and comparable to other international studies. Wide variations in mean doses are noted across the region.
Conclusion: Baseline figures for Tamil Nadu CT DRLs are provided on the most frequently performed CT examinations. It was noted that there was a wide variation in mean doses among the CT scanners used during diagnosis. The differences in CT dose indices between CT departments as well as identical scanners propose a large potential for optimization of procedures. Further audit are mandatory to reduce patient doses, these include periodical re audits, establishment of periodical QA, and opening clinical audits among radiologist to categorize and get rid of unjustified CT procedures.