scholarly journals Scan Quality and Entrance Skin Dose in Thoracic CT: A Comparison between Bismuth Breast Shield and Posteriorly Centered Partial CT Scans

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Rafel Tappouni ◽  
Bradley Mathers
Keyword(s):  
Image Quality ◽  
Anterior Chest Wall ◽  
Chest Ct ◽  
Ct Scans ◽  
Skin Dose ◽  
Hounsfield Units ◽  
Anthropomorphic Phantom ◽  
Thoracic Ct ◽  
Entrance Skin Dose ◽  
Effective Doses

Objectives. To compare the effectiveness of the bismuth breast shield and partial CT scan in reducing entrance skin dose and to evaluate the effect of the breast shield on image quality (IQ). Methods. Nanodots were placed on an adult anthropomorphic phantom. Standard chest CT, CT with shield, and partial CT were performed. Nanodot readings and effective doses were recorded. 50 patients with chest CTs obtained both with and without breast shields were reviewed. IQ was evaluated by two radiologists and by measuring Hounsfield units (HUs) and standard deviation (SD) of HU in anterior subcutaneous region. Results. Breast shield and the partial CT scans reduced radiation to the anterior chest by 38% and 16%, respectively. Partial CT increased dose to the posterior chest by 37% and effective dose by 8%. Change in IQ in shield CT was observed in the anterior chest wall. Significant change in IQ was observed in 5/50 cases. The shield caused an increase of 20 HU () and a 1.86 reduction in SD of HU () in the anterior compared to posterior subcutaneous regions. Summary. Bismuth breast shield is more effective than the partial CT in reducing entrance skin dose while maintaining image quality.

scholarly journals A resource for the assessment of lung nodule size estimation methods: database of thoracic CT scans of an anthropomorphic phantom

2010 ◽  
Vol 18 (14) ◽  
pp. 15244 ◽  
Author(s):  
Marios A. Gavrielides ◽  
Lisa M. Kinnard ◽  
Kyle J. Myers ◽  
Jennifer Peregoy ◽  
William F. Pritchard ◽  
...  
Keyword(s):  
Lung Nodule ◽  
Estimation Methods ◽  
Ct Scans ◽  
Size Estimation ◽  
Anthropomorphic Phantom ◽  
Nodule Size ◽  
Thoracic Ct

scholarly journals CT Thorax lavdose - En sammenligning av et organdosemodulerings program X-CARE og vismut beskyttelse

2017 ◽  
Vol 3 (1) ◽  
pp. 10
Author(s):  
Mikael Oseberg ◽  
Vanessa Tran ◽  
Kim Hoang ◽  
Hilde Lauvhaug ◽  
Hung Thai Phero Nguyen
Keyword(s):  
Image Quality ◽  
Dose Reduction ◽  
Low Dose ◽  
Region Of Interest ◽  
Lung Parenchyma ◽  
Ct Scans ◽  
Parietal Pleura ◽  
Ct Examination ◽  
Thoracic Ct ◽  
Bismuth Shielding

InnledningComputertomografi (CT) er en hyppig utført undersøkelse i Norge. Både mammae og thyroidea er strålefølsomme organer som eksponeres ved en CT thorax undersøkelse. For å få ned inngangsdosen (ESD) til slike strålefølsomme organer kan man enten benytte seg av en organspesifikk adaptiv dose reduksjons protokoll (X-CARE) eller  isteden legge vismut beskyttelse over de strålefølsomme organene ved CT-undersøkelsen. I denne studien sammenligner vi huddosen (ESD) over mamma, samt bildekvalitet, ved bruk av disse to metodene ved en CT thorax lavdose undersøkelse?Material og metode30 spiral skanninger, hvorav ti standard lavdose, ti med vismut beskyttelse og ti med X-CARE, ble utført på et Alderson fantom, kombinert med Care Dose 4D, på en Siemens SOMATOM Definition Edge 128 CT maskin. ESD ble målt, CTDIvol og Dose-lengde-produkt (DLP) ble hentet ut fra doserapporten. Den objektive bildekvaliteten ble analysert, og vurdert ved hjelp av tre Region Of Interest (ROI), plassert hhv i luft, i lungeparenkymet og i pleura parietale. Signal til støyforhold (SNR) og kontrast til støyforhold (CNR) ble regnet ut ifra ROI verdiene.ResultaterESD til mamma viste dosereduksjon sammenlignet med en standard CT thorax lavdose; hhv 16,5 % dosereduksjon ved bruk av vismut beskyttelse, og 0,44 % ved X-CARE. Det var ingen forskjell i CTDIvol og DLP ved standard lavdose skanningen eller skanningen med vismut beskyttelse. Skanningen med X-CARE ga en økning i CTDIvol og DLP på omtrent 12 %. SNR og CNR i lungeparenkymet og pleura parietale var høyest ved standard lavdose undersøkelsen. Bildestøyen økte 48 % ved vismut og 26,4 % ved X-CARE.KonklusjonESD ble markant redusert ved CT thorax lavdose undersøkelsen med vismut beskyttelse, men ga samtidig en markant økning i bildestøyen. X-CARE reduserte ESD minimalt sammenlignet med standard lavdose skanningen, men ga økt bildestøy. Den mest effektive måten å oppnå en optimal lavdose undersøkelse på, er ved å utføre en standard CT thorax lavdose protokoll.   AbstractIntroductionComputed tomography (CT) is a frequent examination conducted in Norway. Mammae and thyroid gland are both dose sensitive body organs, which are being exposed during a thoracic CT examination. Therefore, an optimization of protocols is necessary and X-CARE (organ-based tube current modulation) or bismuth protection may be applied during a CT examination. Will the two methods give a difference in the entrance surface dose (ESD) to mamma and the image quality of a low-dose thoracic CT examination?Materials and methodsThirty spiral CT scans of which ten was standard low-dose, ten with bismuth shielding and ten with X-CARE was performed on an Alderson phantom, combined with CARE Dose 4D and carried out on a Siemens SOMATOM Definition Edge 128. Measures as ESD, CTDIvol and Dose-length-product (DLP) were obtained from the dose report. The image quality was analysed objectively and assessed using three Region of Interest (ROI), placed in air, lung parenchyma and parietal pleura. Signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated from the ROI results.ResultsESD to the mammary gland demonstrated a dose reduction compared to a standard thoracic CT low dose. Respectively; 16.5 % dose reduction with bismuth shielding and 0.44 % with X-CARE. There was no difference in CTDIvol and DLP between the standard low-dose scans and the scans with bismuth shielding. The CT scans with X-CARE gave an increase in CTDIvol and DLP by approximately 12 %. SNR and CNR in the lung parenchyma and parietal pleura were highest during the standard low-dose scans. Bismuth shielding increased the noise with 48 % and X-CARE with 26,4 %.ConclusionESD was significantly reduced during the CT thoracic low-dose examination using bismuth shielding, however notably the bismut increased the image noise. X-CARE reduced the ESD minimally compared to the CT low-dose scans, and it also increased the image noise. The most efficient way to achieve an optimal thoracic CT examination is to use a standard low-dose protoco 

REDUCING ABSORBED DOSE TO THYROID IN NECK CT EXAMINATIONS: THE EFFECTS OF SABA SHIELDING

2020 ◽  
Vol 191 (3) ◽  
pp. 349-360
Author(s):  
Valiallah Saba ◽  
Jalal Kargar Shuraki ◽  
Abdollah Valizadeh ◽  
Mohsen Zahedinia ◽  
Maziar Barkhordari
Keyword(s):  
Image Quality ◽  
American Association ◽  
Absorbed Dose ◽  
Skin Dose ◽  
Radiation Attenuation ◽  
Patient Study ◽  
Entrance Skin Dose ◽  
Radiosensitive Organs ◽  
Attenuation Values

Abstract Bi shielding has been used for the protection of radiosensitive organs during computed tomography (CT) for 20 years. In 2017, American Association of Physicists in Medicine recommended against Bi shielding due to its degrading effects on image quality. Saba shielding introduced recently protecting organs as Bi shielding without degrading image quality. In this study, the Saba shield was modified and primary radiation attenuation values of the shields and entrance skin dose (ESD) on the thyroid were measured with and without shielding. Furthermore, the quality of images obtained using Saba shielding was investigated quantitatively and qualitatively. Saba and Bi shielding reduced the ESD on the thyroid by about 50%. Saba shielding had about 5–7 HU less noise and about 51–65 HU less CT numbers shift in comparison with Bi shielding at a distance of 1 cm from the shields. Saba shielding had no degrading effects on image quality in the patient study.

scholarly journals Investigation of Exposure Factors for Various Breast Composition and Thicknesses in Digital Screening Mammography Related to Breast Dose

2018 ◽  
Vol 27 (3) ◽  
pp. 211-216 ◽  
Author(s):  
Khaled Alkhalifah ◽  
Ajit Brindhaban
Keyword(s):  
Image Quality ◽  
Nonparametric Tests ◽  
Screening Mammography ◽  
Amorphous Selenium ◽  
Skin Dose ◽  
Reference Systems ◽  
Mean Glandular Dose ◽  
Entrance Skin Dose ◽  
Mammography Image

Objective: To investigate the effect of exposure factors used in digital screening mammography on image quality of different breast compositions. Material and Methods: A digital mammography unit, with tungsten (W) as target, rhodium (Rh) and silver (Ag) as filters, and amorphous selenium detectors, was used to image Computerized Imaging Reference Systems (CIRS) Model 12A phantoms of thickness 4, 5, and 6 cm. Images of each phantom were obtained using target-filter combinations of W/Rh and W/Ag, at 28, 30, and 32 kVp. Images were evaluated by 5 senior technologists with experience in mammography. Image scores were assigned, for each type of feature present in the phantom. Statistical analysis was performed using nonparametric tests to compare sets of image scores at p = 0.05. Results: A small but statistically significant improvement was detected in the visibility of microcalcifications (8.8 ± 0.2; p = 0.031) for the W/Rh combination but this did not show any differences in the visibility of masses or fibers. The entrance skin dose (ESD) and mean glandular dose (MGD) were lower for the W/Ag (ESD = 1.30–3.70; MGD = 0.44–0.93 mGy) combination compared to W/Rh (ESD = 1.66–5.40; MGD = 0.52–1.12 mGy). The Mann-Whitney test revealed that 30-kV exposure with the W/Rh combination showed a significantly better visibility of specks in the 30/70 phantom compared to other exposures. Conclusion: The use of an Rh filter showed a better image quality for all phantoms. 28 and 30 kVp with the W/Rh combination provided a slightly better image quality, and the MGD is less than 1.2 mGy.

scholarly journals Image Quality and Radiation Dose for Fibrofatty Breast using Target/filter Combinations in Two Digital Mammography Systems

2020 ◽  
Vol 10 ◽  
pp. 56
Author(s):  
Khaled Alkhalifah ◽  
Akram Asbeutah ◽  
Ajit Brindhaban
Keyword(s):  
Image Quality ◽  
Radiation Dose ◽  
Digital Mammography ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Filter Material ◽  
Skin Dose ◽  
Tissue Equivalent ◽  
Entrance Skin Dose ◽  
Noise Ratio

Objectives: The aim of this study was to determine the optimum combinations of target and filter materials for various X-ray tube voltage settings, as well as their effects on image quality and radiation dose. This was done using different digital mammography (DM) imaging systems with a breast equivalent phantom. Material and Methods: Two DM units with a tungsten (W) target, silver (Ag), and rhodium (Rh) filters and dual molybdenum (Mo) and Rh targets/filters were used. A tissue-equivalent mammography phantom of 6 cm thickness equivalent to a fibrofatty breast was exposed 20 times to different target/filter material combinations (W/Rh, W/Ag, Rh/Rh, Mo/Rh, and Mo/Mo) and various kV settings (28–34 kV). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for each exposure. Results: The W/Ag combination resulted in the lowest entrance skin dose and mean glandular dose (MGD). The MGD for the W/Rh combination was 60% less than that of the W/Ag combination at 34 kV (P < 0.05). There was a direct relationship in the SNR with the Mo/Mo, Mo/Rh, and Rh/Rh combinations and an inverse relationship with the CNR in the 34 kV range. There were statistically significant differences between all five target/filter combinations, and the best SNR and CNR were observed for the W/Rh combination with a reduced radiation dose in the range of 28–30 kV (P < 0.05). Conclusion: For a breast thicknesses of 6 cm with a fibrofatty nature, the W/Rh combination delivers high performance in terms of image quality at a lower dose.

Automated image quality assessment for chest CT scans

2018 ◽  
Vol 45 (2) ◽  
pp. 561-578 ◽  
Author(s):  
Anthony P. Reeves ◽  
Yiting Xie ◽  
Shuang Liu
Keyword(s):  
Image Quality ◽  
Quality Assessment ◽  
Image Quality Assessment ◽  
Chest Ct ◽  
Ct Scans

scholarly journals Reduction of Ovarian Radiation Dose and Image Quality Disruptive Effects: New Constructed Shields for CT Scanning of Abdomen and Pelvis

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Mehran Bagheri ◽  
Mohammad Reza Azimi Aval
Keyword(s):  
Image Quality ◽  
Dose Reduction ◽  
Ct Scanning ◽  
Quality Parameters ◽  
New Combination ◽  
Skin Dose ◽  
Entrance Skin Dose ◽  
Reduction Strategies ◽  
The Right ◽  
User Friendly

Background: Cumulative dose of ovary as a radiosensitive organ during abdominal and pelvic CT scan imaging is still a controversial challenge that requires practical dose reduction strategies. Although bismuth shields can reduce the dose in the right proportions, their use is controversial due to the reduced image quality. Objectives: The aim of this study was to investigate the performance of a new combination of X-ray absorber structures that have less effect on image quality parameters. Methods: First, various shields with different weight percentages of Cu and Bi were made, then the percentage of dose reduction and image quality were evaluated via phantoms. Finally, Shield with the least effect on image quality was evaluated for clinical evaluation on 20 patients. Results: Shielding with thicknesses of 1T and 3T reduced the Entrance skin dose of ovarian by about 52% and 73%, respectively. Shields with 90% cu-10% Bi and 100% Bi structures had the least and most destructive effects on image quality, respectively, and also have the same image quality. The 10% Bi-90% Cu shield provided a 21% greater dose reduction than the bismuth shield. Also, this 1T thick shield did not create an artifact in the reconstructed images. Conclusions: Shields are flexible, inexpensive, and user-friendly for ovarian shielding in abdominal and pelvic CT scans. Unlike bismuth shields, shields do not have the detrimental effects of image quality degradation.

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