Evaluation of Virtual Grid processed clinical pelvic radiographs.

BACKGROUND: A physical scatter grid is not often used in pelvic bedside examinations. However, multiple studies regarding scatter correction software (SC SW) are available for mobile chest radiography but the results are unclear for pelvic radiography. PURPOSE: We evaluated SC SW of Fujifilm (Virtual Grid) on gridless pelvic radiographs obtained from a human Thiel-embalmed body to investigate the potential of Virtual Grid in pelvic bedside examinations. METHODS: Gridless, Virtual Grid, and physical grid pelvic radiographs of a female Thiel-embalmed body were collected with a broad range of tube loads. Different software (SW) grid ratios-6:1, 10:1, 13:1, 17:1, and 20:1-were applied on the gridless radiographs to investigate the image quality (IQ) improvement of 13 IQ criteria in a visual grading analysis (VGA) setup. RESULTS: Gridless radiograph scores are significantly lower (p < 0.001) than Virtual Grid and physical grid scores obtained with the same tube load. Virtual Grid radiographs score better than gridless radiographs obtained with a higher tube load which makes a dose reduction possible. The averaged ratings of the IQ criteria processed with different SW ratios increase with increasing SW grid ratios. However, no statistically significant differences were found between the SW grid ratios. The scores of the physical grid radiographs are higher than those of the Virtual Grid radiographs when they are obtained with the same tube load. CONCLUSION: We conclude that Virtual Grid with an SW ratio of 6:1 improves the IQ of gridless pelvic radiographs in such a manner that a dose reduction is possible. However, physical grid radiograph ratings are higher compared to those of Virtual Grid radiographs.

Integrity of personal radiation protective equipment (PRPE): a 4-year longitudinal follow-up study.

BACKGROUND: Personal radiation protective equipment (PRPE) such as lead aprons minimises radiation exposure of operators using X-ray systems. However, PRPE might be prone to cracks in the attenuating layer resulting in inadequate radiation protection. This study aims to investigate the prevalence, qualification and quantification of PRPE integrity during a longitudinal follow-up study. METHODS: All PRPE of a large, general hospital was evaluated yearly in the period 2018-2021. The equipment was inspected on a tele-operated X-ray table, and tears were qualified and quantified using an X-ray opaque ruler. Rejection criteria of Lambert & McKeon, with an extra rejection criterion of 15 mm2 for individual tears, were applied to accept or reject further use of the PRPE. RESULTS: Over the 4-year follow-up period, a total of 1011 pieces of PRPE were evaluated. In total, 47.3% of the PRPE showed tears of which 31% exceeded the mentioned rejection criteria. Remarkably, of the 287 newly registered pieces of PRPE, 6.0% showed tears in the first year of use of which 88.2% needed to be rejected. Also, 48% of the repaired PRPE was rejected again in the consecutive year. CONCLUSIONS: PRPE is prone to cracks. Up to 50% of PRPE showed tears and cracks resulting in 31% rejections. Newly purchased PRPE is not guaranteed to remain free of cracks and tears in the first year of use. Repair does not guarantee a long-term solution for prolonging the lifespan. Regular X-ray-based integrity analysis of PRPE is needed to ensure adequate radioprotection for operators using X-ray systems.

Evaluation of Virtual Grid Processed Clinical Chest Radiographs.

OBJECTIVES: We evaluated the different Virtual Grid software ratios (Fujifilm, Tokyo, Japan) on gridless clinical chest radiographs with visual grading analysis (VGA). In addition, we investigated the 2 image quality assessment algorithms (IQAAs). MATERIALS AND METHODS: Gridless chest radiographs of 50 different intensive care unit patients were collected and afterward processed with Virtual Grid software. Different software (SW) grid ratios-6:1, 10:1, 13:1, 17:1, and 20:1-were applied to investigate the image quality (IQ) improvement. Image quality improvement was assessed by 4 radiologists in a relative VGA study where the reference image was processed with SW grid ratio of 10:1. One of the IQAAs used to analyze the radiographs was implemented in our department but was originally developed by the research group of the Duke University Medical Center. A general IQ score (IQS) was calculated based on contrast, detail, and noise. Another IQAA-NIQE (naturalness image quality evaluator)-available in Matlab (MATLAB Research R2019b; the MathWorks, Inc) was evaluated. Both methods were compared with VGA. RESULTS: Visual grading analysis scores of gridless radiographs are significantly lower ( P < 0.001). Image quality increases with increasing SW grid ratios, up to grid ratio of 17:1. However, some anatomical structures-spine and ribs-are negatively affected by the higher grid ratios. A correlation coefficient of 0.99 between the VGA and the IQS was observed. The correlation coefficient between VGA and NIQE was 1.00. CONCLUSIONS: Virtual Grid with SW grid ratio of 6:1 improves the IQ of gridless chest bedside radiographs. The grid ratios 17:1 and 20:1 should be considered carefully as the SW negatively affects parts of the ribs and spine. Therefore, grid ratios up to 13:1 can be advised. The IQAAs are promising and could be used to detect differences in IQ when different scatter correction SW settings are used.

Characterizing Scatter Correction Software of 5 Mobile Radiography Units: An Anthropomorphic Phantom Study.

OBJECTIVES: Bedside radiographs are usually obtained gridless, without a physical scatter correction grid because of several limitations. Therefore, multiple manufacturers of mobile radiography systems provide the possibility to apply scatter correction software (SC SW) on those images. The purpose of this study was to characterize different series of radiographs-gridless, SC SW, and physical grid-with an image quality assessment algorithm (IQAA). Furthermore, we investigated the potential dose reduction and the correlation between the output of the IQAA and the human observers. MATERIALS AND METHODS: We obtained different series of radiographs with an anthropomorphic phantom (multipurpose chest phantom N1 "Lungman," Kyoto Kagaku, Kyoto, Japan). All radiographs were obtained with flat-panel detectors of 5 different manufacturers in a wall bucky system. An IQAA to analyze the radiographs was implemented in our department but was originally developed by the research group of the Duke University Medical Center. Seven physical quantities were calculated by the IQAA: rib-lung contrast (RLcontrast), subdiaphragm-lung contrast (SLcontrast), lung detail (Ldetail), mediastinum detail (Mdetail), lung noise (Lnoise), mediastinum noise (Mnoise), and rib-lung sharpness (RLsharpness). In a proof of concept, the results of the IQAA were validated by 3 experienced radiologists. RESULTS: Regression coefficients (b) of the linear regression model indicate that the human observer results correlate well with the IQAA (b ≥ 0.89, R2 ≥ 0.83). All manufacturers have SC SW that increases the 7 physical quantities of the gridless images. However, several manufacturers have SC SW that increases the physical metrics to the same level as the physical grid images. The SC SW radiographs obtained with a reduced tube load have an increased level of contrast, detail, sharpness, and noise compared with the gridless images obtained with the higher tube load. CONCLUSIONS: We have proven in a proof of concept that the originally developed IQAA can be used to characterize different series of images of different manufacturers. Based on the physical quantities, SC SW increases the contrast, detail, sharpness, and noise. The experimental results in this study assume a patient dose reduction could be possible when SC SW is applied.

Impact of Software Parameter Settings on Image Quality of Virtual Grid Processed Radiography Images: A Contrast-Detail Phantom Study.

Mobile radiography systems are commonly used in the intensive care unit. The use of a physical antiscatter grid with these systems is uncommon because of drawbacks. In 2015, Virtual Grid (Fujifilm, Tokyo, Japan) became available for chest and abdomen examinations. In this study, we compared image quality (IQ) with a contrast-detail phantom (CDRAD 2.0; Artinis Medical Systems, Zetten, the Netherlands) of digital radiographs acquired without any grid (gridless) with those corrected for scatter by either software (SW)-based scatter correction (Virtual Grid) or a physical grid (grid). Furthermore, we determined the optimal Virtual Grid settings that lead to the best contrast-detail IQ score (inverse IQ figure). MATERIALS AND METHODS: Images were obtained with a cassette spot film device with an inserted portable flat-panel detector (Fujifilm, Tokyo, Japan). The CDRAD phantom was sandwiched between polymethylmethacrylate (PMMA) with total thicknesses of 12, 16, 21, and 26 cm to simulate patient attenuation and scatter. Tube voltages of 81, 90, 109, and 125 kVp were used to make the radiographs. In total, 12 different Virtual Grid settings (grid ratio, line pairs (lp)/cm, and type of interstitial material) were applied for every phantom thickness and tube voltage. RESULTS: An average increase of 32% in IQ was obtained when Virtual Grid images with a SW grid ratio 10:1 were compared with gridless images (P < 0.001). Increasing the SW grid ratio to 20:1 resulted in a further increased IQ. With a phantom thickness of 12 cm PMMA, Virtual Grid outperformed the removable physical grid presented in the cassette spot film device. The linear mixed-effects model showed that IQ is mainly affected by PMMA, tube voltage, and the SW grid ratio. CONCLUSIONS: Virtual Grid improves images obtained without physical grid for a wide range of experimental conditions. Despite the different possible settings of the Virtual Grid SW, the most important parameter affecting IQ is the SW grid ratio.