Новые возможности в Компьютерной Томографии с model-based итеративной реконструкцией 1 Об оценке радиационной безопасности населения при медицинском облучении и эффективности санитарного надзора • Суммарное количество всех диагностических рентгенорадиологических процедур в России в 2012 году достигло 241 млн. и наблюдается устойчивый рост: на 40% за последние 10 лет • Наибольший вклад в коллективную дозу медицинского облучения пациентов в 2012 году внесли рентгенографические исследования - 34 % (при объеме исследований в 64%) и КТ - 30 % (при объеме исследований в 2%) • За 10 лет вклад компьютерной томографии в коллективную дозу медицинского облучения вырос в 3 раза. 2 3 4 5 Iterative Model-Based Reconstruction A New Era of CT Image Quality 6 По данным измерения на фантоме Catphan 500 3T МРТ Диагностированное поражение на КТ, подтвержденное на МРТ у того же пациента 7 Virtually Noise-Free Images Revealing Critical Information 73 - 90% Noise Reduction* Standard Reconstruction 8 * Image noise as defined by IEC standard 61223-3-5. Image noise was assessed using a Reference Chest Protocol, on a phantom. Data on file. Improve low-contrast detectability Detect Small and Subtle Differences 0.68 mm slice thickness 0.68 mm slice thickness Standard Reconstruction (FBP) 80 kVp, 500 mAs, 9.8 mGy, 170.5 mGy×cm, 2.5 mSv (k=0.015*) 9 Courtesy: Guangdong General Hospital, China * Low-contrast detectability was assessed using a Reference Abdomen Protocol, on the MITA IQ phantom, using human observers. Data on file. * AAPM technical report 96 * Virtually Noise-Free Images* Standard Reconstruction *In clinical practice, IRT may reduce image noise depending on the clinical task, patient size, anatomical location, and clinical practice. A consultation with a radiologist and a physicist should be made to determine the appropriate dose to obtain diagnostic image quality for the particular task. As with any imaging reconstruction, the quality of the resulting IRT images is dependent on the scanning parameters required for your particular patient, clinical indication, and clinical practice. 10 Standard reconstruction IMR 11 7 month old Abdomen Standard Reconstruction IMR Standard Reconstruction IMR Level 3 80 kVp, 70 mAs, Coverage 29.4 cm, CTDIvol 1.5 mGy, DLP 51.5 mGy×cm, 12 Courtesy of University of Maryland Medical Center Pediatric Soft Tissue Neck Standard Reconstruction IMR Level 3 80 kVp, 151mAs/slice, Coverage 15.3 cm, CTDIvol 3.0 mGy, DLP 45.9 mGy×cm, Effective Dose 0.5 mSv (k=0.021)*, * AAPM technical report 96 13 Cardiac 100 kVp, 150 mAs/slice, CTDIvol 7.1 mGy, DLP 92.0 mGy×cm, Effective Dose 1.2 mSv (k=0.014)*, * AAPM technical report 96 Courtesy of: MT. Sinai 14 Abdomen 3 mm slice Standard Reconstruction 3 mm Slice iDose4 Level 7 0.67 mm slice IMR Level 3 120 kVp, 125 mAs, CTDIvol 5.5mGy, DLP: 190.3 mGy×cm, Effective Dose: 2.8 mSv (k=0.015) * AAPM technical report 96 , Courtesy of: Fletcher Allen Medical Center 15 Abdomen Standard Reconstruction IMR 120 kVp, 128 mAs/slice, CTDIvol 9.4 mGy, DLP 348.74mGy×cm, Effective Dose 5.2mSv (k=0.015)*, * AAPM technical report 96 Courtesy of Fletcher Allen Medical Center 16 Abdomen Standard Reconstruction IMR 120 kVp, 128 mAs/slice, CTDIvol 9.4 mGy, DLP 348.74mGy×cm, Effective Dose 5.2mSv (k=0.015)*, * AAPM technical report 96 Courtesy of Fletcher Allen Medical Center 17 Abdomen Standard Reconstruction IMR 80 kVp, 500 mAs/slice, CTDIvol 16.9 mGy, DLP 380.2 mGy×cm, Effective Dose 5.7 mSv (k=0.015)*, * AAPM technical report 96 Courtesy of : GD General Hospital 18 Chest Standard Reconstruction IMR 80 kVp, 10 mAs/slice, CTDIvol 0.2 mGy, DLP 6.36 mGy×cm, Effective Dose 0.11 mSv (k=0.014)*, * AAPM technical report 96 Courtesy of: UCL Utrecht 19 Brain Standard Reconstruction iDose4 IMR 120 kVp, 400 mAs, CTDIvol 53.6 mGy, DLP 857.6 mGy×cm, Effective Dose 1.8 mSv (k=0.0021)* * AAPM technical report 96 Courtesy of Carmel Medical Center Israel 20 Brain 3mm Standard Reconstruction 3 mm iDose4 Level 5 1 mm IMR Level 3 120 kVp, 300 mAs, CTDIvol 14.3 mGy, DLP 866 mGy×cm, Effective Dose 1.8 mSv (k=0.0021)* * AAPM technical report 96 Courtesy of UCL 21 Thoracic Spine Standard Reconstruction IMR 120 kVp, 104 mAs/slice, CTDIvol 6.8 mGy, DLP 234.6 mGy×cm, Effective Dose 3.2mSv (k=0.014)*, * AAPM technical report 96 22 Paper – A phantom study of image quality of 6 iterative reconstruction algorithms for Brain CT* • Evaluated “the image quality produced by six different iterative reconstruction (IR) algorithms in four CT systems in the setting of brain CT, using different radiation levels and iterative optimisation levels.”1 • The statistical iterative reconstruction products evaluated were: – iDose4 (Philips); ASiR (GE); SAFIRE (Siemens); AIDR3D (Toshiba) • The Model-based iterative reconstruction products evaluated were: – IMR (Philips); Veo (GE) • Regarding CNR, “Both model-based algorithms clearly improve spatial resolution. This is particularly remarkable for Philips IMR, which at the same time greatly reduces noise.”1 • Conclusion: “The four statistical IR algorithms evaluated in the study all improved the general image quality compared with FBP, with improvement seen for most or all evaluated quality criteria. Further improvement was achieved with one of the model-based IR algorithms.”1 (IMR was that model-based IR algorithm.) 1Six iterative reconstruction algorithms in brain CT: a phantom study on image quality at different radiation dose levels. Askell Löve, MD, et. al. Skåne University Hospital, Lund University, Lund, Sweden British Journal of Radiology DOI 10.1259/bjr.20130388 Accepted: 16 September 2013 23 24