Study of Contrast-to-Noise Ratio performance of a Medipix3RX CdTe detector for low dose mammography imaging

Objectives: Modern reconstruction and post-processing software aims at reducing image noise in CT images, potentially allowing for a reduction of the employed radiation exposure. This study aimed at assessing the influence of a novel deep-learning based software on the subjective and objective image quality compared to two traditional methods [filtered back-projection (FBP), iterative reconstruction (IR)]. Methods: In this institutional review board-approved retrospective study, abdominal low-dose CT images of 27 patients (mean age 38 ± 12 years, volumetric CT dose index 2.9 ± 1.8 mGy) were reconstructed with IR, FBP and, furthermore, post-processed using a novel software. For the three reconstructions, qualitative and quantitative image quality was evaluated by means of CT numbers, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in six different ROIs. Additionally, the reconstructions were compared using SNR, peak SNR, root mean square error and mean absolute error to assess structural differences. Results: On average, CT numbers varied within 1 Hounsfield unit (HU) for the three assessed methods in the assessed ROIs. In soft tissue, image noise was up to 42% lower compared to FBP and up to 27% lower to IR when applying the novel software. Consequently, SNR and CNR were highest with the novel software. For both IR and the novel software, subjective image quality was equal but higher than the image quality of FBP-images. Conclusion: The assessed software reduces image noise while maintaining image information, even in comparison to IR, allowing for a potential dose reduction of approximately 20% in abdominal CT imaging. Advances in knowledge: The assessed software reduces image noise by up to 27% compared to IR and 48% compared to FBP while maintaining the image information. The reduced image noise allows for a potential dose reduction of approximately 20% in abdominal imaging.

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Non-enhanced versus low-dose contrast-enhanced renal magnetic resonance angiography at 7 T: a feasibility study

Acta Radiologica ◽

10.1177/0284185117718399 ◽

2017 ◽

Vol 59 (3) ◽

pp. 296-304 ◽

Cited By ~ 2

Author(s):

Anja Laader ◽

Karsten Beiderwellen ◽

Oliver Kraff ◽

Stefan Maderwald ◽

Mark E Ladd ◽

...

Keyword(s):

Magnetic Resonance ◽

Magnetic Resonance Angiography ◽

Low Dose ◽

Contrast Ratio ◽

Three Dimensional ◽

Renal Arteries ◽

Tof Mra ◽

Contrast Enhanced ◽

Noise Ratio ◽

Renal Mra

Background Considering the currently reported association between a repetitive application and cumulative dosage of Gadolinium (Gd)-based contrast agents and Gd-deposition in brain tissue as well as the risk for the advent of nephrogenic systemic fibrosis (NSF), techniques allowing for a dose reduction become an important key aspect aside from non-enhanced magnetic resonance angiography (MRA) techniques. Thus, this study was focused on the reduction and/or complete omission of contrast agent for renal MRA at 7T. Purpose To evaluate the performance of time-of-flight MRA versus low-dose contrast-enhanced (CE) renal MRA at 7T. Material and Methods Ten healthy volunteers were examined on a 7T MR system comprising a TOF MRA and three-dimensional (3D) fast low angle shot spoiled gradient-echo sequence (FLASH) MRA after administration of one-quarter of clinical dose of gadobutrol. Qualitative image analysis was performed including overall image quality, artery delineation and presence of artifacts. Contrast ratio (CR), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the renal arteries were calculated. Results TOF MRA and low-CE MRA achieved comparable overall ratings, with slightly superior delineation of the main renal arteries in TOF MRA (TOF = 3.10 ± 0.75, low-CE = 2.95 ± 0.75). Segmental branches outside and inside the parenchyma were delineated significantly better on TOF MRA. Quantitative analysis demonstrated the superiority of TOF MRA, yielding higher scores for CR, SNR, and CNR. Conclusion The initial results of our study demonstrate the feasibility and comparable diagnostic performance of TOF and low-dose CE renal MRA at 7T.

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Intervariability in radiographic parameters and general evaluation of a low-dose fluoroscopic technique in patients with idiopathic scoliosis

Acta Radiologica Open ◽

10.1177/20584601211043258 ◽

2021 ◽

Vol 10 (9) ◽

pp. 205846012110432

Author(s):

Christian Wong ◽

Jens Adriansen ◽

Jytte Jeppsen ◽

Andreas Balslev-Clausen

Keyword(s):

Image Quality ◽

Idiopathic Scoliosis ◽

Low Dose ◽

Signal To Noise Ratio ◽

Radiographic Images ◽

Dose Area Product ◽

General Evaluation ◽

Radiographic Parameters ◽

Cobb’S Angle ◽

Noise Ratio

Background Radiographic images in adolescent idiopathic scoliosis (AIS) have a potential radiation-induced oncogenic effect; thus lowering radiation dose by using fluoroscopic imaging technique of low-dose fluoroscopic technique (LFT) which might be relevant for clinical evaluation. Purpose To compare radiographs of LFT with gold standard radiographs for AIS ordinary radiographic technique (ORT). Material and Methods Image quality was evaluated for LTF and ORT of a child phantom and two 3D-printed models (3DPSs) of AIS. We measured the primary physical characteristics of noise, contrast, spatial resolution, signal-to-noise ratio, and contrast-to-noise ratio. Three independent evaluators assessed the radiographs by observer-based methods of image criteria (ICS) and visual grading analysis(VGAS). Radiation doses were evaluated by the dose-area-product (DAP) of the 25 phantom radiographs. Reliability and agreement of Cobb’s angle (CA) and other radiographic parameters were evaluated on the 3DPSs and reliability on 342 LFT. Results The average noise and contrast were approximately 15-fold higher for LFT. SNR and CNR were similar. Overall, ICS and VGAS were 3-fold higher for ORT than for LFT for L3 and similar for Th6. Reliability and agreement were good for the experimental LFT, and the interclass correlation coefficient for CA was 0.852 for the clinical LFT. The average DAP and effective dose for LFT were 8-fold lower than those for ORT. Conclusion In conclusion, LFT is reliable for CA measurements and is thus useful for clinical outpatient follow-up evaluation. Even though the image quality is lower for LFT than ORT, the merits are the substantially reduced radiation and a lowered malignancy risk without compromising the measurement of Cobb’s angle, thus following the principles of ALARA.

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The Effects Of High Dose and Low Dose Protocols In Thorax’s CT Scan Image Quality

INDONESIAN JOURNAL OF APPLIED PHYSICS ◽

10.13057/ijap.v11i2.48365 ◽

2021 ◽

Vol 11 (2) ◽

pp. 189

Author(s):

Ni Larasati Kartika Sari ◽

Deni Tiko Bahagia ◽

Puji Hartoyo ◽

Dewi Muliyati

Keyword(s):

Computed Tomography ◽

Image Quality ◽

Ct Scan ◽

Spatial Resolution ◽

Low Dose ◽

High Dose ◽

Ct Number ◽

Noise Ratio ◽

Computed Tomography Dose Index ◽

Dose Index

ABSTRACTThe aim of this research was to evaluate the effects of two different dose protocols’ usage on image quality. This research was performed on three different CT Scanners using high dose and low dose protocols of thorax scan. Different exposure parameters were used, depending on each scanner’s setting. GE QA CT Scan phantom was used for image quality assessment. Image quality measured were CT number accuracy, uniformity and linearity, noise uniformity, spatial resolution and Contrast To Noise Ratio (CNR). CT Scan’s dose index, CTDIvol (Volumetric Computed Tomography Dose Index), was also measured to evaluate how these two protocols work in reducing radiation dose. The result showed that the usage of low dose protocols reduce the CTDIvol value at 85-91% compared to the high dose protocols, meanwhile most of the image quality parameters obtained from both protocols were still considered good. The CT number accuracy, uniformity, linearity and noise uniformity for all CT Scans were all still inside BAPETEN’s (Indonesia National Regulator Agency) threshold. There were 20-23% difference on the spatial resolution value measured from both protocols. The most significant difference came from CNR. The CNR obtained from high dose protocols were 65-93% higher than the one from low dose protocols. Keywords: contrast to noise ratio, CTDIvol, CT number, spatial resolutionABSTRAKPenelitian ini mengevaluasi pengaruh penggunanaan protokol dosis tinggi dan protokol dosis rendah terhadap kualitias citra dan dosis khususnya pada pemeriksaan CT Scan thorax. Penelitian ini dilakukan pada 3 sampel CT Scan yang berbeda. Faktor eksposi yang digunakan berbeda untuk tiap scanner, bergantung pada setting yang terdapat pada scanner. Fantom yagdigunakan untuk menilai kualitas citra adalah fantom GE QA CT Scan. Adapun kualitas citra yang diukur adalah keseragaman, akurasi, dan linearitas CT number, keseragaman noise, resolusi spasial, serta Contrast to Noise Ratio (CNR). Sementara dosis radiasi yang diamati adalah CTDIvol (Volumetrik Computed Tomography Dose Index) yang tampil pada konsol. Hasil penelitian ini menunjukkan bahwa penggunaan protokol dosis rendah mampu mengurangi nilai CTDIvol sebesar 85-91% dibanding dengan protokol dosis tinggi, sementara sebagian besar parameter kualitas citra yang diukur masih dinilai baik. Nilai akurasi, keseragaman, dan linearitas CT number serta keseragaman noise pada protokol dosis tinggi dan dosis rendah, keseluruhannya masih dalam batas ambang BAPETEN. Terdapat perbedaan sebesar 20-23% pada nilai resolusi spasial yang terukur dari kedua protokol. Nilai CNR pada protokol dosis tinggi lebih baik dari pada protokol dosis rendah, dengan perbedaan yang cukup signifikan, yaitu 65-93%.Kata kunci: contrast to noise ratio, CTDIvol, CT number, resolusi spasial

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Iterative reconstruction improves image quality and reduces radiation dose in trauma protocols; A human cadaver study

Acta Radiologica Open ◽

10.1177/20584601211055389 ◽

2021 ◽

Vol 10 (10) ◽

pp. 205846012110553

Author(s):

Johannes Clemens Godt ◽

Cathrine K Johansen ◽

Anne Catrine T Martinsen ◽

Anselm Schulz ◽

Helga M Brøgger ◽

...

Keyword(s):

Computed Tomography ◽

Image Quality ◽

Dose Reduction ◽

Iterative Reconstruction ◽

Low Dose ◽

Human Cadaver ◽

Full Dose ◽

Significant Difference ◽

Noise Ratio ◽

Dose Levels

Background Radiation-related cancer risk is an object of concern in CT of trauma patients, as these represent a young population. Different radiation reducing methods, including iterative reconstruction (IR), and spilt bolus techniques have been introduced in the recent years in different large scale trauma centers. Purpose To compare image quality in human cadaver exposed to thoracoabdominal computed tomography using IR and standard filtered back-projection (FBP) at different dose levels. Material and methods Ten cadavers were scanned at full dose and a dose reduction in CTDIvol of 5 mGy (low dose 1) and 7.5 mGy (low dose 2) on a Siemens Definition Flash 128-slice computed tomography scanner. Low dose images were reconstructed with FBP and Sinogram affirmed iterative reconstruction (SAFIRE) level 2 and 4. Quantitative image quality was analyzed by comparison of contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). Qualitative image quality was evaluated by use of visual grading regression (VGR) by four radiologists. Results Readers preferred SAFIRE reconstructed images over FBP at a dose reduction of 40% (low dose 1) and 56% (low dose 2), with significant difference in overall impression of image quality. CNR and SNR showed significant improvement for images reconstructed with SAFIRE 2 and 4 compared to FBP at both low dose levels. Conclusions Iterative image reconstruction, SAFIRE 2 and 4, resulted in equal or improved image quality at a dose reduction of up to 56% compared to full dose FBP and may be used a strong radiation reduction tool in the young trauma population.

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Contrast-to-Noise Ratio and Low-Contrast Object Resolution on Full- and Low-Dose MDCT: SAFIRE Versus Filtered Back Projection in a Low-Contrast Object Phantom and in the Liver

American Journal of Roentgenology ◽

10.2214/ajr.11.7421 ◽

2012 ◽

Vol 199 (1) ◽

pp. 8-18 ◽

Cited By ~ 125

Author(s):

Mark E. Baker ◽

Frank Dong ◽

Andrew Primak ◽

Nancy A. Obuchowski ◽

David Einstein ◽

...

Keyword(s):

Low Dose ◽

Back Projection ◽

Filtered Back Projection ◽

Low Contrast ◽

Noise Ratio

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Diagnostic performance and image quality of deep learning image reconstruction (DLIR) on unenhanced low-dose abdominal CT for urolithiasis

Acta Radiologica ◽

10.1177/02841851211035896 ◽

2021 ◽

pp. 028418512110358

Author(s):

Aurélien Delabie ◽

Roger Bouzerar ◽

Raphaël Pichois ◽

Xavier Desdoit ◽

Jérémie Vial ◽

...

Keyword(s):

Deep Learning ◽

Image Reconstruction ◽

Image Quality ◽

Low Dose ◽

Signal To Noise Ratio ◽

Intraclass Correlation ◽

Reconstruction Algorithm ◽

Urinary Stones ◽

Abdominopelvic Ct ◽

Noise Ratio

Background Patients with urolithiasis undergo radiation overexposure from computed tomography (CT) scans. Improvement of image reconstruction is necessary for radiation dose reduction. Purpose To evaluate a deep learning-based reconstruction algorithm for CT (DLIR) in the detection of urolithiasis at low-dose non-enhanced abdominopelvic CT. Material and Methods A total of 75 patients who underwent low-dose abdominopelvic CT for urolithiasis were retrospectively included. Each examination included three reconstructions: DLIR; filtered back projection (FBP); and hybrid iterative reconstruction (IR; ASiR-V 70%). Image quality was subjectively and objectively assessed using attenuation and noise measurements in order to calculate the signal-to-noise ratio (SNR), absolute contrast, and contrast-to-noise ratio (CNR). Attenuation of the largest stones were also compared. Detectability of urinary stones was assessed by two observers. Results Image noise was significantly reduced with DLIR: 7.2 versus 17 and 22 for ASiR-V 70% and FBP, respectively. Similarly, SNR and CNR were also higher compared to the standard reconstructions. When the structures had close attenuation values, contrast was lower with DLIR compared to ASiR-V. Attenuation of stones was also lowered in the DLIR series. Subjective image quality was significantly higher with DLIR. The detectability of all stones and stones >3 mm was excellent with DLIR for the two observers (intraclass correlation [ICC] = 0.93 vs. 0.96 and 0.95 vs. 0.99). For smaller stones (<3 mm), results were different (ICC = 0.77 vs. 0.86). Conclusion For low-dose abdominopelvic CT, DLIR reconstruction exhibited image quality superior to ASiR-V and FBP as well as an excellent detection of urinary stones.

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High-quality low-dose cardiovascular computed tomography (CCT) in pediatric patients using a 64-slice scanner

Acta Radiologica ◽

10.1177/0284185117752981 ◽

2018 ◽

Vol 59 (10) ◽

pp. 1247-1253 ◽

Cited By ~ 2

Author(s):

Paola Maria Cannaò ◽

Francesco Secchi ◽

Marco Alì ◽

Ida Daniela D'Angelo ◽

Marco Scarabello ◽

...

Keyword(s):

Computed Tomography ◽

Image Quality ◽

Radiation Dose ◽

Effective Dose ◽

Low Dose ◽

Signal To Noise Ratio ◽

High Quality ◽

Dose Length Product ◽

Noise Ratio ◽

Estimate Radiation Dose

Background Cardiovascular computed tomography (CCT) technology is rapidly advancing allowing to perform good quality examinations with a radiation dose as low as 1.2 mSv. However, latest generation scanners are not available in all centers. Purpose To estimate radiation dose and image quality in pediatric CCT using a standard 64-slice scanner. Material and Methods A total of 100 patients aged 6.9 ± 5.4 years (mean ± standard deviation) who underwent a 64-slice CCT scan using 80, 100, or 120 kVp, were retrospectively evaluated. Radiation effective dose was calculated on the basis of the dose length product. Two independent readers assessed the image quality through signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and a qualitative score (3 = very good, 2 = good, 1 = poor). Non-parametric tests were used. Results Fifty-five exams were not electrocardiographically (ECG) triggered, 20 had a prospective ECG triggering, and 25 had retrospective ECG triggering. The median effective dose was 1.3 mSv (interquartile range [IQR] = 0.8–2.7 mSv). Median SNR was 30.6 (IQR = 23.4–33.6) at 120 kVp, 29.4 (IQR = 23.7–34.8) at 100 kVp, and 24.7 (IQR = 19.4–34.3) at 80 kVp. Median CNR was 21.0 (IQR = 14.8–24.4), 19.1 (IQR = 15.6–23.9), and 25.3 (IQR = 19.4–33.4), respectively. Image quality was very good, good, and poor in 56, 39, and 5 patients, respectively. No significant differences were found among voltage groups for SNR ( P = 0.486), CNR ( P = 0.336), and subjective image quality ( P = 0.296). The inter-observer reproducibility was almost perfect (κ = 0.880). Conclusion High-quality pediatric CCT can be performed using a 64-slice scanner, with a radiation effective dose close to 2 mSv in about 50% of the cases.

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Low-Dose 68 Ga-PSMA Prostate PET/MRI Imaging Using Deep Learning Based On MR Priors

10.21203/rs.3.rs-972414/v1 ◽

2021 ◽

Author(s):

Fuquan Deng ◽

Xiaoyuan Li ◽

Fengjiao Yang ◽

Hongwei Sun ◽

Jianmin Yuan ◽

...

Keyword(s):

Prostate Cancer ◽

Nuclear Medicine ◽

Deep Learning ◽

Low Dose ◽

Imaging Method ◽

Learning Methods ◽

Full Dose ◽

Multiple Imaging ◽

Psma Pet ◽

Noise Ratio

Abstract Purpose: 68 Ga-prostate-specific membrane antigen (PSMA) PET/MRI has become an effective imaging method for prostate cancer. The purpose of this study was to use deep learning methods to perform low-dose image restoration on PSMA PET/MRI and to evaluate the effect of synthesis on the images and the medical diagnosis of patients at risk of prostate cancer.Methods: We reviewed the 68 Ga-PSMA PET/MRI data of 41 patients. The low-dose PET images of these patients were restored to full-dose PET images through a deep learning method based on MR priors. The synthesized images were evaluated according to quantitative scores from nuclear medicine doctors and multiple imaging indicators, such as peak-signal noise ratio (PSNR), structural similarity (SSIM), normalization mean square error (NMSE), and relative contrast-to-noise ratio (RCNR).Results: The scores of the full images synthesized from 25%- and 50%-dose images based on MR priors were 3.84±0.36 and 4.03±0.17, respectively, which were higher than the scores of the target images. Correspondingly, the PSNR, SSIM, NMSE, and RCNR values of the full-dose images synthesized from 25%-dose PET images based on MR priors were 37.86±4.16, 0.916±0.063, 0.015±0.012, and 1.004±0.126, respectively.Conclusion: According to a combination of quantitative scores from nuclear medicine doctors and evaluations with multiple image indicators, the synthesis of full-dose images based on MR priors using 25%- and 50%-dose PET images did not affect the clinical diagnosis of prostate cancer. Prostate cancer patients can undergo 68 Ga-PSMA prostate PET/MRI scans with radiation doses reduced by up to 75% through the use of deep learning methods to synthesize full-dose images.

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