TOTAL EFFECTIVE RADIATION-DOSE FROM SPIRAL CT AND CONVENTIONAL RADIOGRAPHY OF THE PELVIS WITH REGARD TO FRACTURE CLASSIFICATION

Purpose: In most departments CT has replaced special radiographic proj ections with regard to classification of pelvic fractures. This change of procedure calls for analysis in terms of dosimetry. Methods: The t otal effective radiation doses given with spiral CT and conventional 5 projection radiography were determined according to ICRP 60 by measur ing organ doses with an anthropomorphic Rando Alderson phantom packed with thermoluminescence dosimeters. For comparison, easily obtainable calculated effective doses were also determined, based on the CT dose index (CTDI), measured free-in-air and as entrance surface dose using organ conversion factors according to NRPB-R250 and NRPB-R262. Results : The total effective radiation dose was lower in spiral CT than in co nventional 5 projection radiography, 4.4 and 5.0 mSv, respectively. In spiral CT the calculated effective dose was 11% lower and in conventi onal radiography 68% higher than the dose obtained by actual measureme nt using the Alderson phantom. Conclusion: As CT gives important diagn ostic information with regard to classification of pelvic fractures, a nd without a greater radiation risk than impacted by 5 projection conv entional radiography, we recommend the performance of spiral CT instea d of special projections.