TH-EF-BRA-07: A Reference Organ Dose Database for Body CT Examination Based On AAPM 246.

PURPOSE: This study aims to establish a reference organ dose database for clinical body CT based on detailed modeling of patient anatomy and irradiation condition. METHODS: Clinical CT images of 40 adult patients (age range: 18-78 y.o., 22 male, 18 female) were included. Each patient received a chest and abdominopelvic CT examination at our institution. Whole-body computer models were created from clinical CT data, which included most of the radiosensitive organs defined by ICRP Publication 103. A previously-validated Monte Carlo program was used to simulate organ dose for each patient model. The scanner spectrum, geometry and material information of the bowtie filter, and the tube current modulation (TCM) profiles were explicitly modeled. Three examination conditions were modeled: (1) fixed tube current (2) TCM exams with modest modulation strength (alpha = 0.5), and (3) TCM exams with strong modulation strength (alpha = 1).The calculated organ dose values were provided as a reference database for dosimetry benchmarking for chest and abdominopelvic examinations. RESULTS: Given the examination CTDIvol to be 7 mGy, organ dose for chest examination were in the range of 1.42 mGy to 14.4 mGy. For abdominopelvic examination, organ dose were in the range of 1.71 mGy to 10.5 mGy. Organ dose shows a gradual decrease with the increase of tube current modulation level. For chest scan, the average organ dose decreased 42.8% for the heart, and 25.0% for the lungs for strong modulation scans compared to no modulation. For abdominopelvic scan, the average organ dose decreased 33.8% for the stomach and 31.6% for the liver when implemented with strong TCM modulation compared to no modulation. CONCLUSION: A database of organ dose estimation is provided with information available for detailed modeling of the patient anatomy and scanner irradiation condition. Such database may be used as a reference standard in quantification and reporting of organ doses. Research fundings from GE, Siemens, and Carestream.

Duke Scholars

Author Ehsan Samei Radiology