Radiation dose and diagnostic image quality associated with iterative reconstruction in coronary CT angiography: A systematic review

J of Medical Radiation Sci

et al. 2018

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IntroductionAn ideal organ‐specific insert phantom should be able to simulate the anatomical features with appropriate appearances in the resultant computed tomography (CT) images. This study investigated a 3D printing technology to develop a novel and cost‐effective cardiac insert phantom derived from volumetric CT image datasets of anthropomorphic chest phantom.MethodsCardiac insert volumes were segmented from CT image datasets, derived from an anthropomorphic chest phantom of Lungman N‐01 (Kyoto Kagaku, Japan). These segmented datasets were converted to a virtual 3D‐isosurface of heart‐shaped shell, while two other removable inserts were included using computer‐aided design (CAD) software program. This newly designed cardiac insert phantom was later printed by using a fused deposition modelling (FDM) process via a Creatbot DM Plus 3D printer. Then, several selected filling materials, such as contrast media, oil, water and jelly, were loaded into designated spaces in the 3D‐printed phantom. The 3D‐printed cardiac insert phantom was positioned within the anthropomorphic chest phantom and 30 repeated CT acquisitions performed using a multi‐detector scanner at 120‐kVp tube potential. Attenuation (Hounsfield Unit, HU) values were measured and compared to the image datasets of real‐patient and Catphan® 500 phantom.ResultsThe output of the 3D‐printed cardiac insert phantom was a solid acrylic plastic material, which was strong, light in weight and cost‐effective. HU values of the filling materials were comparable to the image datasets of real‐patient and Catphan® 500 phantom.ConclusionsA novel and cost‐effective cardiac insert phantom for anthropomorphic chest phantom was developed using volumetric CT image datasets with a 3D printer. Hence, this suggested the printing methodology could be applied to generate other phantoms for CT imaging studies.

Section: Discussionsupporting

confidence: 92%

Development of an organ‐specific insert phantom generated using a 3D printer for investigations of cardiac computed tomography protocols

J of Medical Radiation Sci

et al. 2018

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“…The results demonstrated that the IR ASIR 60% with a low tube voltage of 100 kVp produced comparable SNR to the current local CCTA protocols of 120 kVp and ASIR 40% resulting in a > 50% reduction in radiation dose as measured by the CTDI vol . In our previous systematic review, 22 we concluded that using an IR algorithm allows up to 41% dose reduction as compared to FBP while maintaining similar image quality. Our findings have revealed that although the IR algorithm is already a powerful tool to reduce dose, the higher IR strength at a lower tube voltage has resulted in a further dose reduction.…”

Section: Discussionmentioning

confidence: 87%

“…The 3D‐printed cardiac insert phantom, simulating the contrast‐enhanced region of the ascending aorta and coronary vessels in CCTA, was constructed using 3D printing technology and placed within an anthropomorphic chest phantom (Lungman N‐01, Kyoto Kagaku Co., Ltd., Kyoto, Japan). The development of the 3D‐printed cardiac insert phantom was described in our previous work 22 . The contrast medium used was Ultravist 370 (Schering Health Care Ltd, Burgess Hill, UK).…”

Section: Methodsmentioning

confidence: 99%

Increasing iterative reconstruction strength at low tube voltage in coronary CT angiography protocols using 3D‐printed and Catphan^® 500 phantoms

J Applied Clin Med Phys

et al. 2020

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Purpose The purpose of this study was to investigate the effect of increasing iterative reconstruction (IR) algorithm strength at different tube voltages in coronary computed tomography angiography (CCTA) protocols using a three‐dimensional (3D)‐printed and Catphan® 500 phantoms. Methods A 3D‐printed cardiac insert and Catphan 500 phantoms were scanned using CCTA protocols at 120 and 100 kVp tube voltages. All CT acquisitions were reconstructed using filtered back projection (FBP) and Adaptive Statistical Iterative Reconstruction (ASIR) algorithm at 40% and 60% strengths. Image quality characteristics such as image noise, signal–noise ratio (SNR), contrast–noise ratio (CNR), high spatial resolution, and low contrast resolution were analyzed. Results There was no significant difference (P > 0.05) between 120 and 100 kVp measures for image noise for FBP vs ASIR 60% (16.6 ± 3.8 vs 16.7 ± 4.8), SNR of ASIR 40% vs ASIR 60% (27.3 ± 5.4 vs 26.4 ± 4.8), and CNR of FBP vs ASIR 40% (31.3 ± 3.9 vs 30.1 ± 4.3), respectively. Based on the Modulation Transfer Function (MTF) analysis, there was a minimal change of image quality for each tube voltage but increases when higher strengths of ASIR were used. The best measure of low contrast detectability was observed at ASIR 60% at 120 kVp. Conclusions Changing the IR strength has yielded different image quality noise characteristics. In this study, the use of 100 kVp and ASIR 60% yielded comparable image quality noise characteristics to the standard CCTA protocols using 120 kVp of ASIR 40%. A combination of 3D‐printed and Catphan® 500 phantoms could be used to perform CT dose optimization protocols.

“…The volume of CT dose index (CTDI vol ) for the 4 protocols was 19.2 mGy, 11.6 mGy, 5.8 mGy and 2.9 mGy, representing dose reductions of 40%, 70% and 85%, respectively. These dose reductions were chosen based on the previous work 6 . The detector collimation was 1 x 16 mm, the display field of view (DFOV) was 350 mm, and gantry rotation time was 0.75 s. Data acquisitions of the phantom were repeated thirty times for each exposure settings.…”

Section: Acquisition Protocolsmentioning

confidence: 99%

“…However, FBP results in images that can be deteriorated by both electronic and quantum noise. 6 Iterative reconstruction (IR) algorithms allow using lowdose CT protocols while maintaining the image quality. It uses statistical noise models to optimise the image quality of the final image.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of an integrated 3D‐printed phantom for coronary CT angiography using iterative reconstruction algorithm

J of Medical Radiation Sci

et al. 2020

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Introduction 3D‐printed imaging phantoms are now increasingly available and used for computed tomography (CT) dose optimisation study and image quality analysis. The aim of this study was to evaluate the integrated 3D‐printed cardiac insert phantom when evaluating iterative reconstruction (IR) algorithm in coronary CT angiography (CCTA) protocols. Methods The 3D‐printed cardiac insert phantom was positioned into a chest phantom and scanned with a 16‐slice CT scanner. Acquisitions were performed with CCTA protocols using 120 kVp at four different tube currents, 300, 200, 100 and 50 mA (protocols A, B, C and D, respectively). The image data sets were reconstructed with a filtered back projection (FBP) and three different IR algorithm strengths. The image quality metrics of image noise, signal–noise ratio (SNR) and contrast–noise ratio (CNR) were calculated for each protocol. Results Decrease in dose levels has significantly increased the image noise, compared to FBP of protocol A (P < 0.001). As a result, the SNR and CNR were significantly decreased (P < 0.001). For FBP, the highest noise with poor SNR and CNR was protocol D with 19.0 ± 1.6 HU, 18.9 ± 2.5 and 25.1 ± 3.6, respectively. For IR algorithm, the highest strength (AIDR3Dstrong) yielded the lowest noise with excellent SNR and CNR. Conclusions The use of IR algorithm and increasing its strengths have reduced noise significantly and thus increased the SNR and CNR when compared to FBP. Therefore, this integrated 3D‐printed phantom approach could be used for dose optimisation study and image quality analysis in CCTA protocols.