Evaluation of an iterative model-based CT reconstruction algorithm by intra-patient comparison of standard and ultra-low-dose examinations

Background The explosive growth of computer tomography (CT) has led to a growing public health concern about patient and population radiation dose. A recently introduced technique for dose reduction, which can be combined with tube-current modulation, over-beam reduction, and organ-specific dose reduction, is iterative reconstruction (IR). Purpose To evaluate the quality, at different radiation dose levels, of three reconstruction algorithms for diagnostics of patients with proven liver metastases under tumor follow-up. Material and Methods A total of 40 thorax–abdomen–pelvis CT examinations acquired from 20 patients in a tumor follow-up were included. All patients were imaged using the standard-dose and a specific low-dose CT protocol. Reconstructed slices were generated by using three different reconstruction algorithms: a classical filtered back projection (FBP); a first-generation iterative noise-reduction algorithm (iDose4); and a next generation model-based IR algorithm (IMR). Results The overall detection of liver lesions tended to be higher with the IMR algorithm than with FBP or iDose4. The IMR dataset at standard dose yielded the highest overall detectability, while the low-dose FBP dataset showed the lowest detectability. For the low-dose protocols, a significantly improved detectability of the liver lesion can be reported compared to FBP or iDose4 ( P = 0.01). The radiation dose decreased by an approximate factor of 5 between the standard-dose and the low-dose protocol. Conclusion The latest generation of IR algorithms significantly improved the diagnostic image quality and provided virtually noise-free images for ultra-low-dose CT imaging.

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Abdominal CT radiation dose reduction at Siriraj Hospital (Phase II)

The ASEAN Journal of Radiology ◽

10.46475/aseanjr.v21i3.81 ◽

2020 ◽

Vol 21 (3) ◽

pp. 5-24

Author(s):

Piyaporn Apisarnthanarak ◽

Suchanya Hongpinyo ◽

Krittya Saysivanon ◽

Chulaluck Boonma ◽

Sureerat Janpanich ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Dose Reduction ◽

Low Dose ◽

Standard Dose ◽

Image Noise ◽

Satisfaction Score ◽

Abdominal Ct ◽

Low Dose Ct ◽

The Mean

Objective: To compare radiation dose, radiologists’ satisfaction, and image noise between the standard dose abdominal CT currently performed at our hospital and the new automatic tube current modulation (ATCM) low dose abdominal CT, using various parameters (0%, 10%, 20%, and 30%) of the Adaptive Statistical Iterative Reconstruction (ASiR). Materials and Methods: We prospectively performed the ATCM low dose abdominal CT in 111 participants who had prior standard dose CT for comparison. The ATCM low dose CT images were post processed with 4 parameters (0%, 10%, 20% and 30%) of ASiR on a CT workstation. The volume CT dose index (CTDIvol) of the ATCM low dose and the standard dose CT were compared. Four experienced abdominal radiologists independently assessed the quality of the ATCM low dose CT with the aforementioned ASiR parameters using a 5-point-scale satisfaction score (1 = unacceptable, 2 = poor, 3 = average, 4 = good, and 5 = excellent image quality) by using the prior standard dose CT as a reference of an excellent image quality (5). Each reader selected the preferred ASiR parameter for each participant. The image noise of the liver and the aorta in all 5 techniques (1 prior standard dose and 4 current ATCM low dose techniques) was measured. The correlation between the image quality vs the participants’ body mass index (BMI) and waist circumferences were analyzed. Results: The mean CTDIvol of the ATCM low dose CT was significantly lower than of the standard dose CT (7.29 ± 0.20 vs 11.28 ± 0.23 mGy, p<0.001). The mean satisfaction score for the ATCM low dose CT with 0%, 10%, 20% and 30% ASiR were 4.14, 4.16, 4.17, and 4.26, respectively with the ranges of 3 to 5 in all techniques. The preferred ASiR parameters of each participant randomly selected by each reader were varied, depending on the readers’ opinions. The mean image noise of the aorta on the standard dose CT and the ATCM low dose CT with 0%, 10%, 20%, and 30% ASiR was 30.69, 36.60, 34.05, 31.43, and 29.09, respectively, while the mean image noise of the liver was 24.96, 29.90, 27.86, 25.66, and 23.68, respectively. There was a correlation between the image quality (satisfaction score and image noise) vs the participants’ BMI and waist circumferences. Conclusion: The ATCM low dose CT received acceptable radiologists’ satisfaction with significant radiation dose reduction. The increment of ASiR was helpful in reducing the image noise and had a tendency to increase the radiologists’ satisfaction score.

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Ultra-Low-Dose CT of the Thorax Using Iterative Reconstruction: Evaluation of Image Quality and Radiation Dose Reduction

American Journal of Roentgenology ◽

10.2214/ajr.14.13629 ◽

2015 ◽

Vol 204 (6) ◽

pp. 1197-1202 ◽

Cited By ~ 61

Author(s):

Yookyung Kim ◽

Yoon Kyung Kim ◽

Bo Eun Lee ◽

Seok Jeong Lee ◽

Yon Ju Ryu ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Dose Reduction ◽

Iterative Reconstruction ◽

Low Dose ◽

Radiation Dose Reduction ◽

Low Dose Ct

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Application of low-dose CT combined with model-based iterative reconstruction algorithm in oncologic patients during follow-up: dose reduction and image quality

British Journal of Radiology ◽

10.1259/bjr.20201223 ◽

2021 ◽

pp. 20201223

Author(s):

Davide Ippolito ◽

Cesare Maino ◽

Anna Pecorelli ◽

Ilaria Salemi ◽

Davide Gandola ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Dose Reduction ◽

Iterative Reconstruction ◽

Low Dose ◽

Ct Images ◽

Ct Attenuation ◽

Oncologic Patients ◽

Attenuation Values

Objectives: To compare image quality and radiation dose of CT images reconstructed with model-based iterative reconstruction (MBIR) and hybrid-iterative (HIR) algorithm in oncologic patients. Methods: 125 oncologic patients underwent both contrast-enhanced low- (100 kV), and standard (120 kV) dose CT, were enrolled. Image quality was assessed by using a 4-point Likert scale. CT attenuation values, expressed in Hounsfield unit (HU), were recorded within a regions of interest (ROI) of liver, spleen, paraspinal muscle, aortic lumen, and subcutaneous fat tissue. Image noise, expressed as standard deviation (SD), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated. Radiation dose were analyzed. Paired Student’s t-test was used to compare all continuous variables. Results: The overall median score assessed as image quality for CT images with the MBIR algorithm was significantly higher in comparison with HIR [4 (range 3–4) vs 3 (3-4), p = 0.017]. CT attenuation values and SD were significantly higher and lower, respectively, in all anatomic districts in images reconstructed with MBIR in comparison with HIR ones (all p < 0.001). SNR and CNR values were higher in CT images reconstructed with MBIR, reaching a significant difference in all districts (all p < 0.001). Radiation dose were significantly lower in the MBIR group compared with the HIR group (p < 0.001). Conclusions: MBIR combined with low-kV setting allows an important dose reduction in whole-body CT imaging, reaching a better image quality both qualitatively and quantitatively. Advances in knowledge: MBIR with low-dose approach allows a reduction of dose exposure, maintaining high image quality, especially in patients which deserve a longlasting follow-up.

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Evaluation of an iterative model-based reconstruction of pediatric abdominal CT with regard to image quality and radiation dose

Acta Radiologica ◽

10.1177/0284185117728415 ◽

2017 ◽

Vol 59 (6) ◽

pp. 740-747

Author(s):

Marie-Louise Aurumskjöld ◽

Marcus Söderberg ◽

Fredrik Stålhammar ◽

Kristina Vult von Steyern ◽

Anders Tingberg ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Iterative Reconstruction ◽

Low Dose ◽

Pediatric Patients ◽

Standard Dose ◽

Reconstruction Method ◽

Abdominal Ct ◽

Model Based ◽

Iterative Model

Background In pediatric patients, computed tomography (CT) is important in the medical chain of diagnosing and monitoring various diseases. Because children are more radiosensitive than adults, they require minimal radiation exposure. One way to achieve this goal is to implement new technical solutions, like iterative reconstruction. Purpose To evaluate the potential of a new, iterative, model-based method for reconstructing (IMR) pediatric abdominal CT at a low radiation dose and determine whether it maintains or improves image quality, compared to the current reconstruction method. Material and Methods Forty pediatric patients underwent abdominal CT. Twenty patients were examined with the standard dose settings and 20 patients were examined with a 32% lower radiation dose. Images from the standard examination were reconstructed with a hybrid iterative reconstruction method (iDose4), and images from the low-dose examinations were reconstructed with both iDose4 and IMR. Image quality was evaluated subjectively by three observers, according to modified EU image quality criteria, and evaluated objectively based on the noise observed in liver images. Results Visual grading characteristics analyses showed no difference in image quality between the standard dose examination reconstructed with iDose4 and the low dose examination reconstructed with IMR. IMR showed lower image noise in the liver compared to iDose4 images. Inter- and intra-observer variance was low: the intraclass coefficient was 0.66 (95% confidence interval = 0.60–0.71) for the three observers. Conclusion IMR provided image quality equivalent or superior to the standard iDose4 method for evaluating pediatric abdominal CT, even with a 32% dose reduction.

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To investigate dose reduction and comparability of standard dose CT vs Ultra low dose CT in evaluating pulmonary emphysema

Clinical Imaging ◽

10.1016/j.clinimag.2018.10.012 ◽

2019 ◽

Vol 53 ◽

pp. 115-119 ◽

Cited By ~ 4

Author(s):

Ciara O'Brien ◽

Hong Kuan Kok ◽

Brendan Kelly ◽

Kanako Kumamaru ◽

Abhilash Sahadevan ◽

...

Keyword(s):

Dose Reduction ◽

Pulmonary Emphysema ◽

Low Dose ◽

Standard Dose ◽

Low Dose Ct

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Radiation Dose Reduction in Cervical Spine Computed Tomography in Cervical Spine Trauma: Comparison of Low-dose with Standard-dose Multidetector Computed Tomography

Hong Kong Journal of Radiology ◽

10.12809/hkjr1916922 ◽

2019 ◽

Vol 22 (3) ◽

pp. 180-187

Author(s):

KY Man ◽

KM Mo ◽

HT Sung ◽

KY Cho ◽

CW Tam

Keyword(s):

Computed Tomography ◽

Cervical Spine ◽

Radiation Dose ◽

Multidetector Computed Tomography ◽

Dose Reduction ◽

Low Dose ◽

Standard Dose ◽

Radiation Dose Reduction ◽

Cervical Spine Trauma ◽

Spine Trauma

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Utility of Thoracolumbar Low-Dose CT With Model-Based Iterative Reconstruction for Measuring Pedicle Diameter Using a Radiation Dose Less Than a One-Time Lumbar X-Ray

Spine ◽

10.1097/brs.0000000000003210 ◽

2020 ◽

Vol 45 (1) ◽

pp. 38-47 ◽

Cited By ~ 1

Author(s):

Kazutaka Masamoto ◽

Shunsuke Fujibayashi ◽

Bungo Otsuki ◽

Kentaro Hara ◽

Yasuhiro Fukushima ◽

...

Keyword(s):

Radiation Dose ◽

Iterative Reconstruction ◽

Low Dose ◽

X Ray ◽

Low Dose Ct ◽

Model Based

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Radiation dose reduction by using low dose CT protocol of thorax

Radiation Measurements ◽

10.1016/j.radmeas.2012.07.012 ◽

2013 ◽

Vol 55 ◽

pp. 46-50 ◽

Cited By ~ 2

Author(s):

J. Popić Ramač ◽

Ž. Knežević ◽

A. Hebrang ◽

D. Radić Krišto ◽

V. Vidjak ◽

...

Keyword(s):

Radiation Dose ◽

Dose Reduction ◽

Low Dose ◽

Radiation Dose Reduction ◽

Low Dose Ct ◽

Ct Protocol

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Abdominal CT radiation dose optimization at Siriraj Hospital

The ASEAN Journal of Radiology ◽

10.46475/aseanjr.v21i2.80 ◽

2020 ◽

Vol 21 (2) ◽

pp. 28-43

Author(s):

Piyaporn Apisarnthanarak ◽

Chosita Buranont ◽

Chulaluck Boonma ◽

Sureerat Janpanich ◽

Tarntip Suwatananonthakij ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Low Dose ◽

Standard Dose ◽

Image Noise ◽

Abdominal Ct ◽

Low Dose Ct ◽

Excellent Image Quality ◽

Ct Dose ◽

The Mean

OBJECTIVE: To compare radiation dose and image quality between standard dose abdominal CT currently performed at our hospital and new low dose abdominal CT using various percentages (0%, 10%, 20%, and 30%) of Adaptive Statistical Iterative Reconstruction (ASiR). MATERIALS AND METHODS: We prospectively performed low dose abdominal CT (30% reduction of standard tube current) in 119 participants. The low dose CT images were post processed with four parameters (0%, 10%, 20% and 30%) of ASiR. The volume CT dose index (CTDIvol) of standard and low dose CT were compared. Four experienced abdominal radiologists independently assessed the quality of low dose CT with aforementioned ASiR parameters using a 5-point-scale satisfaction score (1 = unacceptable, 2 = poor, 3 = average, 4 = good, and 5 = excellent image quality) by using prior standard dose CT as a reference of excellent image quality (5). Each reader selected the preference ASiR parameter for each participant. The image noise of the liver and the aorta in all 5 (1 prior standard dose and 4 current low dose) image sets was measured. RESULTS: The mean CTDIvol of low dose CT was significantly lower than of standard dose CT (7.17 ± 0.08 vs 12.02 ±1.61 mGy, p<0.001). The mean satisfaction scores for low dose CT with 0%, 10%, 20% and 30% ASiR were 3.95, 3.99, 3.91 and 3.87, respectively with the ranges of 3 to 5 in all techniques. The preferred ASiR parameters of each participant randomly selected by each reader were varied, depending on the readers’ opinions. The mean image noise of the aorta on standard dose CT and low dose CT with 0%, 10%, 20%, and 30% ASiR was 29.07, 36.97, 33.92, 31.49, and 29.11, respectively, while the mean image noise of the liver was 24.60, 30.21, 28.33, 26.25, and 24.32, respectively. CONCLUSION: Low dose CT with 30% reduction of standard mA had acceptable image quality with significantly reduced radiation dose. The increment of ASiR was helpful in reducing image noise.

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