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.

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.

scholarly journals Feasibility study of simultaneous multislice diffusion kurtosis imaging with different acceleration factors in the liver

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hui Xu ◽  
Nan Zhang ◽  
Da-Wei Yang ◽  
Ahong Ren ◽  
Hao Ren ◽  
...  
Keyword(s):  
Image Quality ◽  
Quality Parameters ◽  
Left Lobe ◽  
Diffusion Kurtosis Imaging ◽  
B Values ◽  
Simultaneous Multislice ◽  
Adc Values ◽  
Right Lobe ◽  
The Right ◽  
Diffusion Kurtosis

Abstract Background Simultaneous multislice diffusion-weighted imaging (SMS-DWI) has been used to reduce image acquisition time. The purpose of this study was to investigate the feasibility of diffusion kurtosis imaging (DKI) based on the SMS technique in the liver and the influence of this method compared with that of conventional DWI sequences on image quality and DKI-derived quantitative parameters. Methods Forty volunteers underwent SMS-DWI sequences with acceleration factors of 2 and 3 (SMS2-DWI, SMS3-DWI) and conventional DWI (C-DWI) of the liver with three b-values (50, 800, 2000 s/mm2) in a 3T system. Qualitative image quality parameters and quantitative measurements of the signal-to-noise ratio (SNR), mean kurtosis (MK), mean apparent diffusivity (MD) and apparent diffusion coefficient (ADC) for the liver were compared between the three sequences. Results The scan times of C-DWI, SMS2-DWI, and SMS3-DWI were 4 min 11 s, 2 min 2 s, and 1 min 34 s, respectively. For all image quality parameters, there were no significant differences observed between C-DWI and SMS2-DWI (all p > 0.05) in the images with b-values of 800 and 2000 s/mm2. C-DWI and SMS2-DWI exhibited better scores than SMS3-DWI (all p < 0.01) in the images with b-values of 2000 s/mm2. In the images with b-values of 800 s/mm2, C-DWI and SMS2-DWI exhibited better scores than SMS3-DWI for artefacts and overall image quality (all p < 0.01), and C-DWI exhibited better scores than SMS3-DWI for the visibility of intrahepatic vessels (p < 0.001). There were no significant differences in the sharpness of the right lobe edge (p = 0.144), conspicuity of the left lobe (p = 0.370) or visibility of intrahepatic vessels (p = 0.109) between SMS2-DWI and SMS3-DWI. There were no significant differences in the sharpness of the right lobe edge (p = 0.066) or conspicuity of the left lobe (p = 0.131) between C-DWI and SMS3-DWI. For the b-value of 800 s/mm2, there were no statistically significant differences between SMS2-DWI and C-DWI (p = 1.000) or between SMS2-DWI and SMS3-DWI (p = 0.059), whereas SMS3-DWI had a significantly lower SNR than C-DWI (p = 0.024). For the DKI-derived parameters (MK and MD) and ADC values, there were no significant differences between the three sequences (MK, p = 0.606; MD, p = 0.831; ADC, p = 0.264). Conclusions SMS-DWI with an acceleration factor of 2 is feasible for the liver, resulting in considerable reductions in scan time while maintaining similar image quality, comparable DKI parameters and ADC values compared with those of C-DWI.

scholarly journals A Comparison of Image Quality and Radiation Exposure Between the Mini C-Arm and the Standard C-Arm

Hand ◽  
2018 ◽  
Vol 14 (6) ◽  
pp. 765-769
Author(s):  
Juliaan R. M. van Rappard ◽  
Willy A. Hummel ◽  
Tijmen de Jong ◽  
Chantal M. Mouës
Keyword(s):  
Image Quality ◽  
Radiation Exposure ◽  
Hand Surgery ◽  
Exposure Dose ◽  
Skin Dose ◽  
Flat Panel ◽  
Scatter Radiation ◽  
Entrance Dose ◽  
Entrance Skin Dose ◽  
Intraoperative Fluoroscopy

Background: The use of intraoperative fluoroscopy has become mandatory in osseous hand surgery. Due to its overall practicality, the mini C-arm has gained popularity among hand surgeons over the standard C-arm. This study compares image quality and radiation exposure for patient and staff between the mini C-arm and the standard C-arm, both with flat panel technology. Methods: An observer-based subjective image quality study was performed using a contrast detail (CD) phantom. Five independent observers were asked to determine the smallest circles discernable to them. The results were plotted in a graph, forming a CD curve. From each curve, an image quality figure (IQF) was derived. A lower IQF equates to a better image quality. The patients’ entrance skin dose was measured, and to obtain more information about the staff exposure dose, a perspex hand phantom was used. The scatter radiation was measured at various distances and angles relative to a central point on the detector. Results: The IQF was significantly lower for the mini C-arm resulting in a better image quality. The patients’ entrance dose was 10 times higher for the mini C-arm as compared with the standard C-arm, and the scatter radiation threefold. Conclusions: Due to its improved image quality and overall practicality, the mini C-arm is recommended for hand surgical procedures. To ensure that the surgeons’ radiation exposure is not exceeding the safety limits, monitoring radiation exposure using mini C-arms with flat panel technology during surgery should be done in a future clinical study.

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