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Thomas P, Hayton A, Beveridge T, Marks P, Wallace A. Evidence of dose saving in routine CT practice using iterative reconstruction derived from a national diagnostic reference level survey. Br J Radiol 2015; 88:20150380. [PMID: 26133224 DOI: 10.1259/bjr.20150380] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To assess the influence and significance of the use of iterative reconstruction (IR) algorithms on patient dose in CT in Australia. METHODS We examined survey data submitted to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) National Diagnostic Reference Level Service (NDRLS) during 2013 and 2014. We compared median survey dose metrics with categorization by scan region and use of IR. RESULTS The use of IR results in a reduction in volume CT dose index of between 17% and 44% and a reduction in dose-length product of between 14% and 34% depending on the specific scan region. The reduction was highly significant (p < 0.001, Wilcoxon rank-sum test) for all six scan regions included in the NDRLS. Overall, 69% (806/1167) of surveys included in the analysis used IR. CONCLUSION The use of IR in CT is achieving dose savings of 20-30% in routine practice in Australia. IR appears to be widely used by participants in the ARPANSA NDRLS with approximately 70% of surveys submitted employing this technique. ADVANCES IN KNOWLEDGE This study examines the impact of the use of IR on patient dose in CT on a national scale.
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Affiliation(s)
- P Thomas
- Medical Imaging Section, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, VIC, Australia
| | - A Hayton
- Medical Imaging Section, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, VIC, Australia
| | - T Beveridge
- Medical Imaging Section, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, VIC, Australia
| | - P Marks
- Medical Imaging Section, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, VIC, Australia
| | - A Wallace
- Medical Imaging Section, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, VIC, Australia
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Effect of Model-Based Iterative Reconstruction on CT Number Measurements Within Small (10–29 mm) Low-Attenuation Renal Masses. AJR Am J Roentgenol 2015; 205:85-9. [DOI: 10.2214/ajr.14.13835] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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53
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Laqmani A, Veldhoen S, Dulz S, Derlin T, Behzadi C, Schmidt-Holtz J, Wassenberg F, Sehner S, Nagel HD, Adam G, Regier M. Reduced-dose abdominopelvic CT using hybrid iterative reconstruction in suspected left-sided colonic diverticulitis. Eur Radiol 2015; 26:216-24. [PMID: 26070499 DOI: 10.1007/s00330-015-3810-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 04/13/2015] [Accepted: 04/20/2015] [Indexed: 01/25/2023]
Abstract
OBJECTIVES To assess the effect of hybrid iterative reconstruction (HIR) and filtered back projection (FBP) on abdominopelvic CT with reduced-dose (RD-APCT) in the evaluation of acute left-sided colonic diverticulitis (ALCD). METHODS Twenty-five consecutive patients with suspected ALCD who underwent RD-APCT (mean CTDIvol 11.2 ± 4.2 mGy) were enrolled in this study. Raw data were reconstructed using FBP and two increasing HIR levels, L4 & L6. Two radiologists assessed image quality, image noise and reviewer confidence in interpreting findings of ALCD, including wall thickening, pericolic fat inflammation, pericolic abscess, and contained or free extraluminal air. Objective image noise (OIN) was measured. RESULTS OIN was reduced up to 54 % with HIR compared to FBP. Subjective image quality of HIR images was superior to FBP; subjective image noise was reduced. The detection rate of extraluminal air was higher with HIR L6. Reviewer confidence in interpreting CT findings of ALCD significantly improved with application of HIR. CONCLUSIONS RD-APCT with HIR offers superior image quality and lower image noise compared to FBP, allowing a high level of reviewer confidence in interpreting CT findings in ALCD. HIR facilitates detection of ALCD findings that may be missed with the FBP algorithm. KEY POINTS HIR significantly reduces objective image noise in comparison to conventional FBP. HIR offers superior subjective image quality in comparison to conventional FBP. HIR allows reduced-dose abdominopelvic CT with acceptable image quality. Reviewer confidence in interpreting CT findings in ALCD significantly improves with HIR.
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Affiliation(s)
- Azien Laqmani
- Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany.
| | - Simon Veldhoen
- Department of Diagnostic and Interventional Radiology, University Medical Center Würzburg, Oberdürrbacher Str. 6, 97080, Würzburg, Germany
| | - Simon Dulz
- Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Thorsten Derlin
- Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Cyrus Behzadi
- Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Jakob Schmidt-Holtz
- Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Felicia Wassenberg
- Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Susanne Sehner
- Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Hans-Dieter Nagel
- Scientific and Application-oriented Studies and Consulting in Radiology (SASCRAD), Fritz-Reuter-Weg 5f, 21244, Buchholz, Germany
| | - Gerhard Adam
- Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Marc Regier
- Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
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Radiation Dose Consideration in Kidney Stone CT Examinations: Integration of Iterative Reconstruction Algorithms With Routine Clinical Practice. AJR Am J Roentgenol 2015; 204:1055-63. [PMID: 25905941 DOI: 10.2214/ajr.14.13038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Musculoskeletal wide detector CT: Principles, techniques and applications in clinical practice and research. Eur J Radiol 2015; 84:892-900. [DOI: 10.1016/j.ejrad.2014.12.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 12/15/2014] [Accepted: 12/31/2014] [Indexed: 11/21/2022]
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Ultralow-dose chest computed tomography for pulmonary nodule detection: first performance evaluation of single energy scanning with spectral shaping. Invest Radiol 2015; 49:465-73. [PMID: 24598443 DOI: 10.1097/rli.0000000000000037] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE The purpose of this study was to evaluate the image quality and sensitivity of ultralow radiation dose single-energy computed tomography (CT) with tin filtration for spectral shaping and iterative reconstructions for the detection of pulmonary nodules in a phantom setting. METHODS Single-energy CT was performed using third-generation dual-source CT (SOMATOM Force; 2 × 192 slices) at 70 kVp, 100 kVp with tin filtration (100Sn kVp), and 150Sn kV with tube current-time product adjustments resulting in standard dose (CT volume dose index, 3.1 mGy/effective dose, 1.3 mSv at a scan length of 30 cm), 1/10th dose level (0.3 mGy/0.13 mSv), and 1/20th dose level (0.15 mGy/0.06 mSv). An anthropomorphic chest phantom simulating an intermediate-sized adult with randomly distributed solid pulmonary nodules of various sizes (2-10 mm; attenuation, 75 HU at 120 kVp) was used. Images were reconstructed with advanced model-based iterative reconstruction (ADMIRE; strength levels 3 and 5) and were compared with those acquired with second-generation dual-source CT at 120 kVp (reconstructed with filtered back projection) and sinogram-affirmed iterative reconstruction (strength level 3) at the lowest possible dose at 120 kVp (CT volume dose index, 0.28 mGy). One blinded reader measured image noise, and 2 blinded, independent readers determined overall image quality on a 5-grade scale (1 = nondiagnostic to 5 = excellent) and marked nodule localization with confidence rates on a 5-grade scale (1 = unsure to 5 = high confidence). The constructional drawing of the phantom served as reference standard for calculation of sensitivity. Two patients were included, for proof of concept, who were scanned with the 100Sn kVp protocol at the 1/10th and 1/20th dose level. RESULTS Image noise was highest in the images acquired with second-generation dual-source CT and reconstructed with filtered back projection. At both the 1/10th and 1/20th dose levels, image noise at a tube voltage of 100Sn kVp was significantly lower than in the 70 kVp and 150Sn kV data sets (ADMIRE 3, P < 0.01; ADMIRE 5, P < 0.05). Sensitivity of nodule detection was lowest in images acquired with second-generation dual-source CT at 120 kVp and the lowest possible dose. Protocols at 100Sn kVp and ADMIRE 5 showed highest sensitivity at the 1/10th and 1/20th dose levels. Highest numbers of false-positives occurred in second-generation dual-source CT images (range, 12-15), whereas lowest numbers occurred in the 1/10th and 1/20th dose data sets acquired with third-generation dual-source CT at 100Sn kVp and reconstructed with ADMIRE strength levels 3 and 5 (total of 1 and 0 false-positives, respectively). Diagnostic confidence at 100Sn kVp was significantly higher than at 70 kVp or 150Sn kV (ADMIRE 3, P < 0.05; ADMIRE 5, P < 0.01) at both the 1/10th and 1/20th dose levels. Images of the 2 patients scanned with 100Sn kVp at the 1/10th and 1/20th dose levels were of diagnostic quality. CONCLUSIONS Our study suggests that chest CT for the detection of pulmonary nodules can be performed with third-generation dual-source CT producing high image quality, sensitivity, and diagnostic confidence at a very low effective radiation dose of 0.06 mSv when using a single-energy protocol at 100 kVp with spectral shaping and when using advanced iterative reconstruction techniques.
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Comparison of iterative model-based reconstruction versus conventional filtered back projection and hybrid iterative reconstruction techniques: lesion conspicuity and influence of body size in anthropomorphic liver phantoms. J Comput Assist Tomogr 2015; 38:859-68. [PMID: 25321625 DOI: 10.1097/rct.0000000000000145] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
PURPOSE This study aimed to determine whether an iterative model-based reconstruction (IMR) can improve lesion conspicuity and depiction on computed tomography (CT) compared with filtered back projection (FBP) and hybrid iterative reconstruction (iDose) using anthropomorphic phantoms. MATERIALS AND METHODS One small and one large anthropomorphic body phantoms, each containing 8 simulated focal liver lesions (FLLs), were scanned using a 256-channel CT scanner at 120 kVp with variable tube current-time products (10-200 mAs). Scans were divided into 3 groups based on radiation dose (RD) as follows: (a) full dose (FD), (b) low dose (FD50), and (c) ultralow dose (FD25 for the large phantom, FD15 for the small phantom). All images were reconstructed using FBP, iDose, and IMR. Image noise and lesion-to-liver contrast were assessed quantitatively and qualitatively. Thereafter, 6 radiologists independently evaluated conspicuity of FLLs, and then, compared the number of invisible FLLs on 3 image sets of each RD group. RESULTS Image noise was significantly lower with IMR than with FBP and iDose at the same RD. Iterative model-based reconstruction improved conspicuity of low-contrast FLLs in all RD groups compared to the others (P < 0.001). Furthermore, compared to FBP and iDose, the number of visible FLLs significantly increased on IMR images in the FD15 group of the small phantom 52.8% [38/72], 68.1% [49/72], and 84.8% [61/72], respectively; P < 0.001) and in the FD 25, FD50 groups of the large phantom (FD50: 56.9% [41/72], 76.4% [55/72], and 84.7% [61/72], respectively; P < 0.05). CONCLUSIONS Iterative model-based reconstruction reduced image noise and improved low-contrast FLL conspicuity, compared to FBP and iDose. Therefore, depiction of low-contrast FLLs on FBP could be improved using IMR.
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Sullivan CJ, Murphy KP, McLaughlin PD, Twomey M, O'Regan KN, Power DG, Maher MM, O'Connor OJ. Radiation exposure from diagnostic imaging in young patients with testicular cancer. Eur Radiol 2014; 25:1005-13. [PMID: 25500962 DOI: 10.1007/s00330-014-3507-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 10/30/2014] [Accepted: 11/13/2014] [Indexed: 12/22/2022]
Abstract
OBJECTIVES Risks associated with high cumulative effective dose (CED) from radiation are greater when imaging is performed on younger patients. Testicular cancer affects young patients and has a good prognosis. Regular imaging is standard for follow-up. This study quantifies CED from diagnostic imaging in these patients. METHODS Radiological imaging of patients aged 18-39 years, diagnosed with testicular cancer between 2001 and 2011 in two tertiary care centres was examined. Age at diagnosis, cancer type, dose-length product (DLP), imaging type, and frequency were recorded. CED was calculated from DLP using conversion factors. Statistical analysis was performed with SPSS. RESULTS In total, 120 patients with a mean age of 30.7 ± 5.2 years at diagnosis had 1,410 radiological investigations. Median (IQR) surveillance was 4.37 years (2.0-5.5). Median (IQR) CED was 125.1 mSv (81.3-177.5). Computed tomography accounted for 65.3 % of imaging studies and 98.3 % of CED. We found that 77.5 % (93/120) of patients received high CED (>75 mSv). Surveillance time was associated with high CED (OR 2.1, CI 1.5-2.8). CONCLUSIONS Survivors of testicular cancer frequently receive high CED from diagnostic imaging, mainly CT. Dose management software for accurate real-time monitoring of CED and low-dose CT protocols with maintained image quality should be used by specialist centres for surveillance imaging. KEY POINTS • CT accounted for 98.3 % of CED in patients with testicular cancer. • Median CED in patients with testicular cancer was 125.1 mSv • High CED (>75 mSv) was observed in 77.5 % (93/120) of patients. • Dose tracking and development of low-dose CT protocols are recommended.
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Affiliation(s)
- C J Sullivan
- Department of Radiology, Cork and Mercy University Hospitals, Wilton, Cork, Ireland
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Dose monitoring using the DICOM structured report: assessment of the relationship between cumulative radiation exposure and BMI in abdominal CT. Clin Radiol 2014; 70:176-82. [PMID: 25496824 DOI: 10.1016/j.crad.2014.11.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 10/30/2014] [Accepted: 11/03/2014] [Indexed: 11/24/2022]
Abstract
AIM To perform a systematic, large-scale analysis using the Digital Imaging and Communication in Medicine structured report (DICOM-SR) to assess the relationship between body mass index (BMI) and radiation exposure in abdominal CT. MATERIALS AND METHODS A retrospective analysis of DICOM-SR of 3121 abdominal CT examinations between April 2013 and March 2014 was performed. All examinations were conducted using a 128 row CT system. Patients (mean age 61 ± 15 years) were divided into five groups according to their BMI: group A <20 kg/m(2) (underweight), group B 20-25 kg/m(2) (normal weight), group C 25-30 kg/m(2) (overweight), group D 30-35 kg/m(2) (obese), and group E > 35 kg/m(2) (extremely obese). CT dose index (CTDIvol) and dose-length product (DLP) were compared between all groups and matched to national diagnostic reference values. RESULTS The mean CTDIvol and DLP were 5.4 ± 2.9 mGy and 243 ± 153 mGy.cm in group A, 6 ± 3.6 mGy and 264 ± 179 mGy.cm in group B, 7 ± 3.6 mGy and 320 ± 180 mGy.cm in group C, 8.1 ± 5.2 mGy and 375 ± 306 mGy.cm in group D, and 10 ± 8 mGy and 476 ± 403 mGy.cm in group E, respectively. Except for group A versus group B, CTDIvol and DLP differed significantly between all groups (p<0.05). Significantly more CTDIvol values exceeded national diagnostic reference values in groups D and E (2.1% and 6.3%) compared to group B (0.5%, p<0.05). CONCLUSION DICOM-SR is a comprehensive, fast, and reproducible way to analyse dose-related data at CT. It allows for automated evaluation of radiation dose in a large study population. Dose exposition is related to the patient's BMI and is increased by up to 96% for extremely obese patients undergoing abdominal CT.
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Kim SH, Baek SH, Yoon JH, Lim YJ, Baek HJ, Kim SJ, Eun CK. Quarter regular dose non-enhanced CT for urinary stone: added value of adaptive statistical iterative reconstruction. Acta Radiol 2014; 55:1137-44. [PMID: 24259297 DOI: 10.1177/0284185113513761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND As urinary stone diseases are common in young adults and have a high recurrence rate, repetitive computed tomography (CT) scans would increase the radiation hazard. Therefore, CT radiation dose reduction is needed in the diagnosis of urinary stones. PURPOSE To prospectively evaluate the added value of adaptive statistical iterative reconstruction (ASIR) applied to half-dose (HDCT) and quarter regular dose non-enhanced CT (QDCT) for the detection of urinary stones. MATERIAL AND METHODS One hundred and twelve consecutive patients who presented with acute flank pain and had clinically suspected urinary stones were initially eligible. All patients underwent non-enhanced CT that consisted of HDCT (120 kVp, 100 mAs) and QDCT (120 kVp, 40 mAs). The images were reconstructed separately with a 50% ASIR blending ratio. Two radiologists independently performed a 2-week interval reading to detect urinary stones on a per stone basis (size ≥1 mm) from the QDCT images to the ASIR applied images. Two weeks later, the HDCT images were analyzed in the same manner. The CT image noise was measured for each image set. The sensitivity for urinary stone detection for each set was compared using the McNemar test. RESULTS A total of 114 urinary stones were found in 48 patients (37 men, 11 women; mean age, 46 years; range, 19-71 years). After applying ASIR to the QDCT images, the sensitivity increased from 70% to 80% for reader 1 and from 69% to 82% for reader 2 (P = 0.001, respectively). However, in the HDCT images, the sensitivity was unchanged for both readers (reader 1, 87%; reader 2, 89%). The measured noise significantly decreased from 40.2 to 27.7 after applying ASIR to the QDCT images and from 25.1 to 17.6 after applying ASIR to the HDCT images (P = 0.001 for both). CONCLUSION Although ASIR showed no added diagnostic value for HDCT images, it improved the sensitivity for the detection of urinary stones based on QDCT images.
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Affiliation(s)
- Seung Ho Kim
- Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea
| | - Soo Heui Baek
- Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea
| | - Jung-Hee Yoon
- Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea
| | - Yun-Jung Lim
- Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea
| | - Hye Jin Baek
- Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea
| | - Seon-Jeong Kim
- Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea
| | - Choong Ki Eun
- Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea
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Euler A, Heye T, Kekelidze M, Bongartz G, Szucs-Farkas Z, Sommer C, Schmidt B, Schindera ST. Assessment of image quality and low-contrast detectability in abdominal CT of obese patients: comparison of a novel integrated circuit with a conventional discrete circuit detector at different tube voltages. Eur Radiol 2014; 25:687-93. [DOI: 10.1007/s00330-014-3459-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 09/10/2014] [Accepted: 09/29/2014] [Indexed: 10/24/2022]
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Introduction of an Effective Method for the Optimization of CT Protocols Using Iterative Reconstruction Algorithms: Comparison With Patient Data. AJR Am J Roentgenol 2014; 203:W434-9. [DOI: 10.2214/ajr.13.11973] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Kalmar PI, Quehenberger F, Steiner J, Lutfi A, Bohlsen D, Talakic E, Hassler EM, Schöllnast H. The impact of iterative reconstruction on image quality and radiation dose in thoracic and abdominal CT. Eur J Radiol 2014; 83:1416-20. [DOI: 10.1016/j.ejrad.2014.05.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 05/07/2014] [Accepted: 05/08/2014] [Indexed: 11/25/2022]
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Raman SP, Mahesh M, Blasko RV, Fishman EK. CT scan parameters and radiation dose: practical advice for radiologists. J Am Coll Radiol 2014; 10:840-6. [PMID: 24183553 DOI: 10.1016/j.jacr.2013.05.032] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022]
Abstract
Although there has been increasing recognition of the importance of reducing radiation dose when performing multidetector CT examinations, the increasing complexity of CT scanner technology, as well as confusion about the importance of many different CT scan parameters, has served as an impediment to radiologists seeking to create lower dose protocols. The authors seek to guide radiologists through the manipulation of 8 fundamental CT scan parameters that can be altered or optimized to reduce patient radiation dose, including detector configuration, tube current, tube potential, reconstruction algorithm, patient positioning, scan range, reconstructed slice thickness, and pitch. Although there is always an inherent trade-off between image quality or noise and patient radiation dose, in many cases, a reasoned manipulation of these 8 parameters can allow the safer imaging of patients (with lower dose) while preserving diagnostic image quality.
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Affiliation(s)
- Siva P Raman
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland.
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Integrated circuit detector technology in abdominal CT: added value in obese patients. AJR Am J Roentgenol 2014; 202:368-74. [PMID: 24450679 DOI: 10.2214/ajr.13.10839] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE The purpose of this article was to assess the effect of an integrated circuit (IC) detector for abdominal CT on image quality. MATERIALS AND METHODS In the first study part, an abdominal phantom was scanned with various extension rings using a CT scanner equipped with a conventional discrete circuit (DC) detector and on the same scanner with an IC detector (120 kVp, 150 effective mAs, and 75 effective mAs). In the second study part, 20 patients were included who underwent abdominal CT both with the IC detector and previously at similar protocol parameters (120 kVp tube current-time product and 150 reference mAs using automated tube current modulation) with the DC detector. Images were reconstructed with filtered back projection. RESULTS Image quality in the phantom was higher for images acquired with the IC compared with the DC detector. There was a gradually increasing noise reduction with increasing phantom sizes, with the highest (37% in the largest phantom) at 75 effective mAs (p < 0.001). In patients, noise was overall significantly (p = 0.025) reduced by 6.4% using the IC detector. Similar to the phantom, there was a gradual increase in noise reduction to 7.9% in patients with a body mass index of 25 kg/m(2) or lower (p = 0.008). Significant correlation was found in patients between noise and abdominal diameter in DC detector images (r = 0.604, p = 0.005), whereas no such correlation was found for the IC detector (r = 0.427, p = 0.060). CONCLUSION Use of an IC detector in abdominal CT improves image quality and reduces image noise, particularly in overweight and obese patients. This noise reduction has the potential for dose reduction in abdominal CT.
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Chen JH, Jin EH, He W, Zhao LQ. Combining automatic tube current modulation with adaptive statistical iterative reconstruction for low-dose chest CT screening. PLoS One 2014; 9:e92414. [PMID: 24691208 PMCID: PMC3972172 DOI: 10.1371/journal.pone.0092414] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 02/21/2014] [Indexed: 11/19/2022] Open
Abstract
Objective To reduce radiation dose while maintaining image quality in low-dose chest computed tomography (CT) by combining adaptive statistical iterative reconstruction (ASIR) and automatic tube current modulation (ATCM). Methods Patients undergoing cancer screening (n = 200) were subjected to 64-slice multidetector chest CT scanning with ASIR and ATCM. Patients were divided into groups 1, 2, 3, and 4 (n = 50 each), with a noise index (NI) of 15, 20, 30, and 40, respectively. Each image set was reconstructed with 4 ASIR levels (0% ASIR, 30% ASIR, 50% ASIR, and 80% ASIR) in each group. Two radiologists assessed subjective image noise, image artifacts, and visibility of the anatomical structures. Objective image noise and signal-to-noise ratio (SNR) were measured, and effective dose (ED) was recorded. Results Increased NI was associated with increased subjective and objective image noise results (P<0.001), and SNR decreased with increasing NI (P<0.001). These values improved with increased ASIR levels (P<0.001). Images from all 4 groups were clinically diagnosable. Images with NI = 30 and 50% ASIR had average subjective image noise scores and nearly average anatomical structure visibility scores, with a mean objective image noise of 23.42 HU. The EDs for groups 1, 2, 3 and 4 were 2.79±1.17, 1.69±0.59, 0.74±0.29, and 0.37±0.22 mSv, respectively. Compared to group 1 (NI = 15), the ED reductions were 39.43%, 73.48%, and 86.74% for groups 2, 3, and 4, respectively. Conclusions Using NI = 30 with 50% ASIR in the chest CT protocol, we obtained average or above-average image quality but a reduced ED.
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Affiliation(s)
- Jiang-Hong Chen
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, XiCheng District, Beijing, China
| | - Er-Hu Jin
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, XiCheng District, Beijing, China
- * E-mail:
| | - Wen He
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, XiCheng District, Beijing, China
| | - Li-Qin Zhao
- Department of Radiology, Beijing Friendship Hospital, Capital Medical University, XiCheng District, Beijing, China
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Experiences with the use of iteratively reconstructed dose-modified MDCT angiography examinations of living renal donors. J Comput Assist Tomogr 2014; 38:535-43. [PMID: 24651752 DOI: 10.1097/rct.0000000000000084] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the performance of iteratively reconstructed (IR) dose-modified (DM) multidetector computed tomography (MDCT) angiography (CTA) examinations of renal donors in comparison to standard dose filtered back projection (FBP) images. MATERIALS AND METHODS Eighty-five potential donors who underwent dual-phase CTA on 16-/64-MDCT scanners were retrospectively reviewed. Images from a 16-MDCT scanner were reconstructed with filtered back projection (group A, 47) and examinations from 64-MDCT with IR (group B, 38). Scan parameters were constant for both groups except for higher noise index (× 1.3) in group B. Images were interpreted for the relevant anatomy and IQ by 2 readers. Surgical report served as reference standard for operated kidneys, whereas for nonoperated kidneys, interobserver agreement was evaluated. RESULTS Radiation dose was 36% lower in group B compared to group A. All CTA examinations were rated for diagnostic quality with comparable IQ scores. In 48 operated kidneys, 10 surgically confirmed vascular anomalies were correctly identified by both readers. In the remaining 122 nonoperated kidneys, there was an excellent interobserver agreement. CONCLUSIONS Iteratively reconstructed technique preserves high image quality and diagnostic performance at significantly lower radiation doses in DM kidney donor CTA examinations.
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Kim M, Lee JM, Yoon JH, Son H, Choi JW, Han JK, Choi BI. Adaptive iterative dose reduction algorithm in CT: effect on image quality compared with filtered back projection in body phantoms of different sizes. Korean J Radiol 2014; 15:195-204. [PMID: 24644409 PMCID: PMC3955785 DOI: 10.3348/kjr.2014.15.2.195] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 01/14/2014] [Indexed: 11/15/2022] Open
Abstract
Objective To evaluate the impact of the adaptive iterative dose reduction (AIDR) three-dimensional (3D) algorithm in CT on noise reduction and the image quality compared to the filtered back projection (FBP) algorithm and to compare the effectiveness of AIDR 3D on noise reduction according to the body habitus using phantoms with different sizes. Materials and Methods Three different-sized phantoms with diameters of 24 cm, 30 cm, and 40 cm were built up using the American College of Radiology CT accreditation phantom and layers of pork belly fat. Each phantom was scanned eight times using different mAs. Images were reconstructed using the FBP and three different strengths of the AIDR 3D. The image noise, the contrast-to-noise ratio (CNR) and the signal-to-noise ratio (SNR) of the phantom were assessed. Two radiologists assessed the image quality of the 4 image sets in consensus. The effectiveness of AIDR 3D on noise reduction compared with FBP were also compared according to the phantom sizes. Results Adaptive iterative dose reduction 3D significantly reduced the image noise compared with FBP and enhanced the SNR and CNR (p < 0.05) with improved image quality (p < 0.05). When a stronger reconstruction algorithm was used, greater increase of SNR and CNR as well as noise reduction was achieved (p < 0.05). The noise reduction effect of AIDR 3D was significantly greater in the 40-cm phantom than in the 24-cm or 30-cm phantoms (p < 0.05). Conclusion The AIDR 3D algorithm is effective to reduce the image noise as well as to improve the image-quality parameters compared by FBP algorithm, and its effectiveness may increase as the phantom size increases.
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Affiliation(s)
- Milim Kim
- College of Medicine, Seoul National University, Seoul 110-744, Korea
| | - Jeong Min Lee
- Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea. ; Research Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea
| | - Jeong Hee Yoon
- Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea
| | - Hyoshin Son
- College of Medicine, Seoul National University, Seoul 110-744, Korea
| | - Jin Woo Choi
- Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea
| | - Joon Koo Han
- Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea. ; Research Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea
| | - Byung Ihn Choi
- Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea. ; Research Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea
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Feasibility of Single-Source Dual-Energy Computed Tomography for Urinary Stone Characterization and Value of Iterative Reconstructions. Invest Radiol 2014; 49:125-30. [DOI: 10.1097/rli.0000000000000002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Kulkarni NM, Pinho DF, Kambadakone AR, Sahani DV. Emerging technologies in CT- radiation dose reduction and dual-energy CT. Semin Roentgenol 2014; 48:192-202. [PMID: 23796370 DOI: 10.1053/j.ro.2013.03.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Naveen M Kulkarni
- Massachusetts General Hospital, Division of Abdominal Imaging and Intervention, Boston, MA 02114, USA
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Hybrid Iterative Reconstruction Technique for Abdominal CT Protocols in Obese Patients: Assessment of Image Quality, Radiation Dose, and Low-Contrast Detectability in a Phantom. AJR Am J Roentgenol 2014; 202:W146-52. [DOI: 10.2214/ajr.12.10513] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Images Acquired Using 320-MDCT With Adaptive Iterative Dose Reduction With Wide-Volume Acquisition: Visual Evaluation of Image Quality by 10 Radiologists Using an Abdominal Phantom. AJR Am J Roentgenol 2014; 202:2-12. [DOI: 10.2214/ajr.12.10364] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Xie Q, Wu J, Tang Y, Dou Y, Hao S, Xu F, Feng X, Liang Z. Whole-organ CT perfusion of the pancreas: impact of iterative reconstruction on image quality, perfusion parameters and radiation dose in 256-slice CT-preliminary findings. PLoS One 2013; 8:e80468. [PMID: 24303017 PMCID: PMC3841218 DOI: 10.1371/journal.pone.0080468] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 10/03/2013] [Indexed: 01/29/2023] Open
Abstract
Background This study was performed to assess whether iterative reconstruction can reduce radiation dose while maintaining acceptable image quality, and to investigate whether perfusion parameters vary from conventional filtered back projection (FBP) at the low-tube-voltage (80-kVp) during whole-pancreas perfusion examination using a 256-slice CT. Methods 76 patients with known or suspected pancreatic mass underwent whole-pancreas perfusion by a 256-slice CT. High- and low-tube-voltage CT images were acquired. 120-kVp image data (protocol A) and 80-kVp image data (protocol B) were reconstructed with conventional FBP, and 80-kVp image data were reconstructed with iDose4 (protocol C) iterative reconstruction. The image noise; contrast-to-noise ratio (CNR) relative to muscle for the pancreas, liver, and aorta; and radiation dose of each protocol were assessed quantitatively. Overall image quality was assessed qualitatively. Among 76 patients, 23 were eventually proven to have a normal pancreas. Perfusion parameters of normal pancreas in each protocol including blood volume, blood flow, and permeability-surface area product were measured. Results In the quantitative study, protocol C reduced image noise by 36.8% compared to protocol B (P<0.001). Protocol C yielded significantly higher CNR relative to muscle for the aorta, pancreas and liver compared to protocol B (P<0.001), and offered no significant difference compared to protocol A. In the qualitative study, protocols C and A gained similar scores and protocol B gained the lowest score for overall image quality (P<0.001). Mean effective doses were 23.37 mSv for protocol A and 10.81 mSv for protocols B and C. There were no significant differences in the normal pancreas perfusion values among three different protocols. Conclusion Low-tube-voltage and iDose4 iterative reconstruction can dramatically decrease the radiation dose with acceptable image quality during whole-pancreas CT perfusion and have no significant impact on the perfusion parameters of normal pancreas compared to the conventional FBP reconstruction using a 256-slice CT scanner.
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Affiliation(s)
- Qian Xie
- Department of Radiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Juan Wu
- Department of Radiology, Affiliated Hospital of Nantong University, Nantong University, Nantong, China
| | - Ying Tang
- Department of Radiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Yafang Dou
- Department of Radiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Sijie Hao
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Feijia Xu
- Department of Radiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Xiaoyuan Feng
- Department of Radiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Zonghui Liang
- Department of Radiology, Jing’an District Central Hospital of Shanghai (Jing’an Branch, Huashan Hospital, Fudan University), Shanghai, China
- * E-mail:
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Nance JW, Schoepf UJ, Ebersberger U. The Role of Iterative Reconstruction Techniques in Cardiovascular CT. CURRENT RADIOLOGY REPORTS 2013. [DOI: 10.1007/s40134-013-0023-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kondratyev E, Karmazanovsky G. Low radiation dose 256-MDCT angiography of the carotid arteries: effect of hybrid iterative reconstruction technique on noise, artifacts, and image quality. Eur J Radiol 2013; 82:2233-9. [PMID: 24094643 DOI: 10.1016/j.ejrad.2013.08.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 10/26/2022]
Abstract
UNLABELLED To evaluate the effect of hybrid iterative reconstruction on qualitative and quantitative parameters at low dose carotid CTA. MATERIALS AND METHODS 44 consecutive patients were enrolled in the study. First group (n=22) was examined under 120 kV 250 mAs, second group (n = 22) - 100 kV 250 mAs. CT images in first group were reconstructed only with the filtered back projection (FBP). CT data in second group were reconstructed both with FBP and three levels of hybrid iterative reconstruction algorithm (iDose). We compared quantitative and qualitative parameters among the two groups and among four different reconstructions in second group. RESULTS Effective dose in 120 kV and 100 kV group was 7.18 ± 1.19 mSv and 4.14 ± 1.03 mSv, respectively (p<0.0001). Mean arterial attenuation was about 25% higher in second group (236.5 ± 46 HU vs. 302.6 ± 32.7 HU; p<0.0001). Image noise at the level of humeral belt was 32.5 ± 12.5 in 100 kV group and 26.3 ± 13.3 in 120 kV (p = 0.115). Average noise decreased when using 3 levels of iDose up to 23.6 ± 6.4, 17.7 ± 5.6 and 13.7 ± 5.1, respectively (p = 0.00001). Mean CNR increased to 10.38 ± 3.87, 14.5 ± 5.21 and 18.32 ± 8.61, respectively (p<0.05). The presence of artifacts on the level of humeral belt in 120 kV group was 14%, in 100 kV - 41% (p = 0.002). The difference in visual scores between standard and low-dose protocol was significant (p = 0.008). When applying iterative reconstruction the frequency of streak artifacts decreased dramatically (p<0.0001). Most studies had excellent quality with no artifacts while using highest level of iDose. CONCLUSION According to the results of our study low dose CT angiography using hybrid iterative reconstruction may provide sufficient image quality and allows for significant reduction of patient dose.
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Affiliation(s)
- Evgeny Kondratyev
- Vishnevsky Institute of Surgery, B. Serpukhovskaya 27, 115093 Moscow, Russian Federation.
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Raman SP, Johnson PT, Deshmukh S, Mahesh M, Grant KL, Fishman EK. CT dose reduction applications: available tools on the latest generation of CT scanners. J Am Coll Radiol 2013; 10:37-41. [PMID: 23290672 DOI: 10.1016/j.jacr.2012.06.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 06/18/2012] [Indexed: 12/23/2022]
Abstract
Increasing concerns about radiation dose have led CT manufacturers to further develop radiation dose reduction tools in the latest generation of CT scanners. These tools include automated tube current modulation, automated tube potential selection, and iterative reconstruction. This review details the principles underlying each of these 3 dose reduction utilities and their different permutations on each of the major vendors' equipment. If available on the user's equipment, all 3 of these tools should be used in conjunction to enable maximum radiation dose savings.
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Affiliation(s)
- Siva P Raman
- Department of Radiology, Johns Hopkins University, Baltimore, MD 21287, USA.
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O'Neill SB, Mc Laughlin PD, Crush L, O'Connor OJ, Mc Williams SR, Craig O, Mc Garrigle AM, O'Neill F, Bye J, Ryan MF, Shanahan F, Maher MM. A prospective feasibility study of sub-millisievert abdominopelvic CT using iterative reconstruction in Crohn's disease. Eur Radiol 2013; 23:2503-12. [PMID: 23740025 DOI: 10.1007/s00330-013-2858-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 03/03/2013] [Accepted: 03/17/2013] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Iterative reconstruction (IR) allows diagnostic CT imaging with less radiation exposure than filtered back projection (FBP). We studied an IR low-dose CT abdomen/pelvis (LDCTAP) protocol, designed to image at an effective dose (ED) approximating 1 mSv in patients with Crohn's disease (CD). METHODS Forty patients, mean age 37 ± 13.4 years (range 17-69), with CD underwent two synchronous CT protocols (conventional-dose (CDCTAP) and LDCTAP). CDCTAP and LDCTAP images were compared for diagnostic acceptability, yield, image quality and ED (in millisieverts). The optimal level of IR for LDCTAP was also studied. RESULTS LDCTAP yielded a mean ED of 1.3 ± 0.8 mSv compared with 4.7 ± 2.9 mSv for CDCTAP, reducing ED by 73.7 ± 3.3 % (mean dose reduction, 3.5 ± 2.1 mSv; P < 0.001) and dose length product by 73.6 ± 2.6 % (P < 0.001). Sub-millisievert (0.84 mSv) imaging was performed for patients with a body mass index (BMI) less than 25 (i.e. 63 % of our cohort). LDCTAP resulted in increased image noise and reduced diagnostic acceptability compared with CDCTAP despite use of IR, but detection of extra-luminal complications was comparable. CONCLUSION Patients with suspected active CD can be adequately imaged using LDCTAP, yielding comparable information regarding extent, activity and complications of CD compared with CDCTAP, but with 74 % less dose. LDCTAP at doses equivalent to that of two abdominal radiographs represents a feasible alternative to CDCTAP. KEY POINTS • Radiation dose is a concern when imaging patients with Crohn's disease. • New techniques allow low-dose abdominopelvic CT with acceptable image quality. • Using hybrid iterative reconstruction, its diagnostic yield compares well with that of conventional CT. • Sub-millisievert CT of patients with Crohn's disease appears technically and clinically feasible.
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Affiliation(s)
- Siobhan B O'Neill
- Department of Radiology, Cork University Hospital, Wilton, Cork, Ireland
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Yasaka K, Katsura M, Akahane M, Sato J, Matsuda I, Ohtomo K. Model-based iterative reconstruction for reduction of radiation dose in abdominopelvic CT: comparison to adaptive statistical iterative reconstruction. SPRINGERPLUS 2013; 2:209. [PMID: 23687632 PMCID: PMC3655211 DOI: 10.1186/2193-1801-2-209] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 05/02/2013] [Indexed: 12/24/2022]
Abstract
Purpose To evaluate dose reduction and image quality of abdominopelvic computed tomography (CT) reconstructed with model-based iterative reconstruction (MBIR) compared to adaptive statistical iterative reconstruction (ASIR). Materials and methods In this prospective study, 85 patients underwent referential-, low-, and ultralow-dose unenhanced abdominopelvic CT. Images were reconstructed with ASIR for low-dose (L-ASIR) and ultralow-dose CT (UL-ASIR), and with MBIR for ultralow-dose CT (UL-MBIR). Image noise was measured in the abdominal aorta and iliopsoas muscle. Subjective image analyses and a lesion detection study (adrenal nodules) were conducted by two blinded radiologists. A reference standard was established by a consensus panel of two different radiologists using referential-dose CT reconstructed with filtered back projection. Results Compared to low-dose CT, there was a 63% decrease in dose-length product with ultralow-dose CT. UL-MBIR had significantly lower image noise than L-ASIR and UL-ASIR (all p<0.01). UL-MBIR was significantly better for subjective image noise and streak artifacts than L-ASIR and UL-ASIR (all p<0.01). There were no significant differences between UL-MBIR and L-ASIR in diagnostic acceptability (p>0.65), or diagnostic performance for adrenal nodules (p>0.87). Conclusion MBIR significantly improves image noise and streak artifacts compared to ASIR, and can achieve radiation dose reduction without severely compromising image quality.
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Affiliation(s)
- Koichiro Yasaka
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Image quality of low-dose CCTA in obese patients: impact of high-definition computed tomography and adaptive statistical iterative reconstruction. Int J Cardiovasc Imaging 2013; 29:1565-74. [PMID: 23624958 DOI: 10.1007/s10554-013-0228-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 04/19/2013] [Indexed: 10/26/2022]
Abstract
The accuracy of coronary computed tomography angiography (CCTA) in obese persons is compromised by increased image noise. We investigated CCTA image quality acquired on a high-definition 64-slice CT scanner using modern adaptive statistical iterative reconstruction (ASIR). Seventy overweight and obese patients (24 males; mean age 57 years, mean body mass index 33 kg/m(2)) were studied with clinically-indicated contrast enhanced CCTA. Thirty-five patients underwent a standard definition protocol with filtered backprojection reconstruction (SD-FBP) while 35 patients matched for gender, age, body mass index and coronary artery calcifications underwent a novel high definition protocol with ASIR (HD-ASIR). Segment by segment image quality was assessed using a four-point scale (1 = excellent, 2 = good, 3 = moderate, 4 = non-diagnostic) and revealed better scores for HD-ASIR compared to SD-FBP (1.5 ± 0.43 vs. 1.8 ± 0.48; p < 0.05). The smallest detectable vessel diameter was also improved, 1.0 ± 0.5 mm for HD-ASIR as compared to 1.4 ± 0.4 mm for SD-FBP (p < 0.001). Average vessel attenuation was higher for HD-ASIR (388.3 ± 109.6 versus 350.6 ± 90.3 Hounsfield Units, HU; p < 0.05), while image noise, signal-to-noise ratio and contrast-to noise ratio did not differ significantly between reconstruction protocols (p = NS). The estimated effective radiation doses were similar, 2.3 ± 0.1 and 2.5 ± 0.1 mSv (HD-ASIR vs. SD-ASIR respectively). Compared to a standard definition backprojection protocol (SD-FBP), a newer high definition scan protocol in combination with ASIR (HD-ASIR) incrementally improved image quality and visualization of distal coronary artery segments in overweight and obese individuals, without increasing image noise and radiation dose.
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Body size indices to determine iodine mass with contrast-enhanced multi-detector computed tomography of the upper abdomen: does body surface area outperform total body weight or lean body weight? Eur Radiol 2013; 23:1855-61. [DOI: 10.1007/s00330-013-2808-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 01/21/2013] [Accepted: 02/07/2013] [Indexed: 12/17/2022]
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Desai GS, Thabet A, Elias AYA, Sahani DV. Comparative assessment of three image reconstruction techniques for image quality and radiation dose in patients undergoing abdominopelvic multidetector CT examinations. Br J Radiol 2013; 86:20120161. [PMID: 23255538 DOI: 10.1259/bjr.20120161] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVE To compare image quality and radiation dose of abdominal CT examinations reconstructed with three image reconstruction techniques. METHODS In this Institutional Review Board-approved study, contrast-enhanced (CE) abdominopelvic CT scans from 23 patients were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASiR) and iterative reconstruction in image space (IRIS) and were reviewed by two blinded readers. Subjective (acceptability, sharpness, noise and artefacts) and objective (noise) measures of image quality were recorded for each image data set. Radiation doses in CT dose index (CTDI) dose-length product were also calculated for each examination type and compared. Imaging parameters were compared using the Wilcoxon signed rank test and a paired t-test. RESULTS All 69 CECT examinations were of diagnostic quality and similar for overall acceptability (mean grade for ASiR, 3.9±0.3; p=0.2 for Readers 1 and 2; IRIS, 3.9±0.4, p=0.2; FBP, 3.8±0.9). Objective noise was considerably lower with both iterative techniques (p<0.0001 and 0.0016 for ASiR and IRIS). Recorded mean radiation dose, i.e. CTDI(vol), was 24% and 10% less with ASiR (11.4±3.4 mGy; p<0.001) and IRIS (13.5±3.7 mGy; p=0.06), respectively, than with FBP: 15.0±3.5 mGy. CONCLUSION At the system parameters used in this study, abdominal CT scans reconstructed with ASiR and IRIS provide diagnostic images with reduced image noise and 10-24% lower radiation dose than FBP. ADVANCES IN KNOWLEDGE CT images reconstructed with FBP are frequently noisy on lowering the radiation dose. Newer iterative reconstruction techniques have different approaches to produce images with less noise; ASiR and IRIS provide diagnostic abdominal CT images with reduced image noise and radiation dose compared with FBP. This has been documented in this study.
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Affiliation(s)
- G S Desai
- Department of Radiology, Harvard Medical School, Boston, MA, USA
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Quantitative and Qualitative Comparison of Standard-Dose and Low-Dose Pediatric Head Computed Tomography. J Comput Assist Tomogr 2013; 37:377-81. [DOI: 10.1097/rct.0b013e31828426de] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Pilot Study of Detection, Radiologist Confidence and Image Quality With Sinogram-Affirmed Iterative Reconstruction at Half–Routine Dose Level. J Comput Assist Tomogr 2013; 37:203-11. [DOI: 10.1097/rct.0b013e31827e0e93] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Delfyett WT, Fetzer DT. Imaging of Neurologic Conditions During Pregnancy and the Perinatal Period. Neurol Clin 2012; 30:791-822. [DOI: 10.1016/j.ncl.2012.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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