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1 Clinical Audit on Optimization of Radiation Dose from MDCT: Effect on Diagnostic Reference Levels for Brain, Sinus, Cervical Spine, Chest, Abdomen-Pelvis, and Lumbar Spine Examinations and on Nationwide Collective Effective Dose. Poster No.: C-0066 Congress: ECR 2011 Type: Scientific Exhibit Authors: D. Tack, A. Jahnen, S. Kohler, N. Harpes, C. Back ; Braine L'Alleud/BE, Luxembourg/LU, Luxembourg-Kirchberg/LU Keywords: Radiation safety, Ethics, Education, CT-High Resolution, CTAngiography, CT, Radioprotection, Management DOI: /ecr2011/C-0066 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 54

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3 Purpose Surveys on radiation dose from CTas introduced by the EUR 97/43 Directive intend to stimulate the radiation dose optimization process. Reference Diagnostic Levels (RDLs) defined as 75th percentile of observed dose for a given examination represent the upper limit of acceptable practice. Original historical DRLswere derived from SDCT and were high. In Luxemburg; som DRLs observed in 2007 were even higher (Figure 7). Significant dose reductions between surveys performed on MDCT scanners have not yet been reported, probably because interval between surveys are long (more than 4 years) and because there is no penalty for those who do not optimize, even if their dose levels are higher than DRLs. In order to overcome these problems, the Luxemburg Ministery of Health took the initiative to propose an external audit ans support in MDCT radiation dose in order to obtain rapid dose decrease in all MDCT departments. Purpose of this presentation is to report the effects of an extrnal clinical audit in all MDCT departments in Luxemburg state on DRLs and collective dose delivered in adult patients between two consecutive surveys in 2007 and in Images for this section: Page 3 of 54

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11 Methods and Materials The six most frequent MDCT examinations including Head (He), Sinus (Si), Cervical Spine (CS), Chest (Ch), Abdomen-Pelvis (AP), and Lumbar Spine (LS) - representing 93% of MDCT examinations - were considered. MDCT scanner detector rows ranged from 4 to 40. The auditing process proposed optimized CTDIvol values at 40 mgy for He, 4 mgy for Si, 21 mgy for CS, 6 mgy for Ch, 8 mgy for A-P, and 27 mgy for LS in standard patients. Images for this section: Fig. 1 Page 11 of 54

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17 Results Clinical examples of optimization process in side by side comparisons of standard and optimized acquisitions in the same patients are shown in this section for Head, Sinus, Chest, Abdomen and Lumbar Spine MDCT Examinations. Compared to 2007, the 2009 CTDIvol DRLs (in mgy) were at 50 (- 37%) for He, 5.4 (-71%) for Si, 30 (-70%) for CS, 7.5 (-45%) for Ch, 10.5 (-21%) for A-P, and 34 (-58%) for LS. Annual radiation dose delivered by MDCT per inhabitant was thus reduced by 30%, from 1.9 msv to 1.4 msv. Interrestingly, not only the highest dose were reduced. The P25 values also decreased between 2007 and 2009, indicating that the audi process also helped the best optimized dose levels to be further reduced. All dose reductions reached statistical significance unless those for lumbar spine. An additional audi was conducted in one hospital site in order to acheive L-spine optimization and obtain significant reults later on. Images for this section: Page 17 of 54

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53 Conclusion Clinical audit supporting radiology departments in optimizing the radiation dose delivered by MDCT can help obtaining 20 to 66% reductions in DRLs between consecutive surveys, and a 30% reduction of the collective dose from CT. This one day (per site) process focused on reductions in CTDIvol can be achieved on any MDCT scanner equipped with automatic exposure control (tube current modulation) and is independant on newly developped iterative reconstruction algorithms. However, it does not address the number ow acquisitions per examination nor the zcoverage, both inducung substantial dose increase, mainly in the abdomen. Images for this section: Fig. 1 Page 53 of 54

54 References Optimization and reduction in MDCT with special focus on image quality. D. Tack Diagnostic Imaging - Radiation dose in Adult and Pediatric Multidetector Computed Tomography Springer, New York, Heidelberg 2007 Dose reduction and optimization in computed tomography of the Chest. PA Gevenois, D. Tack Diagnostic Imaging - Radiation dose in Adult and Pediatric Multidetector Computed Tomography Springer, New York, Heidelberg 2007 Dose optimisation and reduction in MDCT of the abdomen. C Keyzer, PA Gevenois, D. Tack Diagnostic Imaging - Radiation dose in Adult and Pediatric Multidetector Computed Tomography Springer, New York, Heidelberg 2007 Personal Information If you need any support in optimization process, contact first author. Page 54 of 54