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Ambient dose during intraoral radiography with current techniques: Part 1 conversion factor for scattered radiation using a rectangular collimator
摘要： The aim of this study was to establish a conversion factor for assessing the scattered radiation produced during intraoral radiography with a rectangular collimator in areas where the remnant beam is not present. The dose level in the remnant beam will be addressed in another study. A radiological phantom (Rando) in the upright position was exposed to radiation delivered by a Planmeca Intra X-ray unit over 9 exposure geometries (right side of a full mouth series). For each geometry, the scattered radiation dose was measured at 5 locations in the horizontal plane and 4 locations in the vertical plane in front of the patient. The measurements were corrected for background and leakage radiation. An inventory of the distributions of the different geometries with respect to their share of the total workload was created in order to assign the correct weightings of the total ambient scattered radiation for the different geometries. The weightings were used to construct a scattered radiation pattern for a representative mix of exposures. The maximum value found in this pattern was used to arrive at a safe conversion factor. The scattered ambient radiation dose was evenly distributed over the horizontal plane. The scattered ambient radiation dose ranged from 20 to 65% lower in the vertical plane. The conversion factor established for scattered ambient radiation was 0.05 μSv per mAs at 1 meter. This factor is 3-fold lower than the conversion factors reported previously.
关键词： radiation protection,dental radiography,radiation monitoring,Dental Equipment
更新于2025-09-23 15:23:52
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Ambient dose during intra-oral radiography with current techniques: Part 2 quantifying the remnant beam - an <i>in vivo</i> study
摘要： Objectives: (1) To find a safe reference transmission factor for the remnant beam to be used when assessing the remnant beam during intra-oral radiography. (2) To identify factors such as exposure type, side (left or right), gender and age that might significantly affect transmission. Methods: Measurements were performed in the remnant beam during 323 intra-oral exposures of 43 patients. The exposure parameters were 60 kV and 7 mA. These measurements were compared with values in the same setting, but without a patient present to arrive at a transmission value. Differences between types of exposure [bitewing (BW), incisor and canine (IC) periapical, premolar and molar (PM) periapical], exposure side (left or right), gender and age were statistically analysed. The reference value was based on the exposure yielding the highest transmission value, to which a safety margin of two standard deviations (SDs) was added, and then rounding up. Results: The respective mean transmission values (SD) for BW, IC and PM exposures were as follows: 1.78% (1.15%), 0.639% (0.63%) and 2.60% (0.98%). The differences between PM and IC and between BW and IC were significant (p > 0.01). The differences between exposure side, gender and age were not significant. The reference transmission value, which was calculated from the highest mean transmission percentage for PM (2.60%) plus twice the SD (0.98%) and rounding up, was 5%. Conclusions: A transmission factor of 5% could be used to assess the remnant beam during intra-oral radiography. Anterior exposures led to significantly lower transmission values than posterior exposures.
关键词： radiation protection,dental radiography,dental equipment,radiation monitoring
更新于2025-09-23 15:23:52
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Potential of GAGG:Ce scintillation crystals for synchrotron X-Ray micro-imaging
摘要： We examined the use of cerium-doped gadolinium aluminum gallium garnet (GAGG:Ce) as a material for scintillation screens in synchrotron X-ray radiography (SXR). Highlighted for gamma-ray detection, GAGG:Ce is also an attractive material for SXR because of its high X-ray stopping power and the high light yield at around 530 nm. A thin and transparent screen prepared from our grown ingot of GAGG:Ce was compared with commonly used scintillators of CdWO4 and YAG:Ce in terms of image quality under monochromatic X-ray illumination. Micron spatial resolutions were achieved with comparable image quality, suggesting that a single crystal of GAGG:Ce is competent scintillation material for SXR.
关键词： Spatial resolutions,GAGG,X-ray detection,Synchrotron X-ray radiography,Scintillator
更新于2025-09-23 15:23:52
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Relationship between body habitus and image quality and radiation dose in chest X-ray examinations: A phantom study
摘要： Purpose: To evaluate the influence of being overweight on image quality (IQ), radiation dose and acquisition parameters when undertaking adult chest X-ray (CXR) examinations using routine acquisition protocols. Methods: The Lungman chest phantom, with and without chest plates, was used to simulate the chest region for larger size and average adult patients, respectively. Radiographic acquisitions were conducted using 17 X-ray machines located in eight hospitals using their routine clinical protocols. IQ was assessed using relative visual grading analysis (VGA) and 2 alternative forced choice (2AFC) by six observers. Incident air kerma (IAK) was measured using a solid-state dosimeter. Results: IQ mean (range) scores between the hospitals were 16.2 (12.0–21.3) with a 56.0% difference and 20.9 (14.1–23.6) with a 50.2% difference for the standard and larger size phantoms, respectively. IAK mean (range) scores 63 μGy (19–136 μGy) with a 150% difference and 159 μGy (27–384 μGy) with a 173% difference for the standard and larger size phantoms, respectively. The chest plates had a significant negative impact on IQ (P = 0.001) and lead to an increased in IAK by approximately 50%. Conclusion: Visual measures of IQ and IAK showed large differences between hospitals for standard and larger phantom sizes; differences within the hospitals was lower. Overall, Lungman with chest plates was found to degrade IQ and increase radiation dose by a factor of two. Further optimisation is required especially for the larger sized patient’s imaging protocols for all eight hospitals.
关键词： Overweight,Image quality,Obesity,Adult chest radiography,Dose optimisation,Radiation dose
更新于2025-09-23 15:23:52
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Visual assessment of calcification in solitary pulmonary nodules on chest radiography: correlation with volumetric quantification of calcification
摘要： Purpose To assess the ability of digital chest radiography (CXR) to reveal calcification in solitary pulmonary nodules (SPNs), and to examine the correlation between a visual assessment and volumetric quantification of the calcification. Materials and methods This study was a retrospective review of 220 SPNs identified by both CXR and chest CT. Eleven observers did blind review of the CXR images and scored nodule calcification on a confidence scale of 1 to 5. The area under the receiver operating characteristics (ROC) curve (AUC) was obtained to analyze the diagnostic performance. The intraclass correlation coefficient (ICC) for interrater reliability was calculated. The AUC and ICC were calculated according to the following nodule diameter groups: group 1 (< 10 mm), group 2 (≥ 10 mm and < 20 mm), and group 3 (≥ 20 mm). Results Of the 220 SPNs, 145 SPNs (65.6%) were identified as non-calcified and 75 (34.4%) as calcified. The average percentage of calcification volume in SPN > 160 HU (Vol160HU) among the 75 calcified nodules was 47.5%. The mean Vol160HU of the 68 SPNs classified as having definite calcification was 51.1%. The overall AUC was 0.71. The AUCs for groups 1, 2, and 3 was 0.835, 0.639, and 0.620, respectively. The ICCs for groups 1, 2, 3 was 0.65, 0.48, and 0.33, respectively. Conclusion The overall diagnostic performance of digital CXR to predict calcification in SPNs was moderately accurate and the diagnostic performance for predicting calcification in SPNs was significantly higher, and interobserver reproducibility was good when SPN < 10 mm compared with ≥ 10 mm in diameter.
关键词： Radiography,Solitary pulmonary nodule,Tomography,thoracic,X-ray computed
更新于2025-09-23 15:23:52
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Imaging Patterns of Pediatric Pulmonary Blastomycosis
摘要： OBJECTIVE. The objective of our study was to characterize and update the radiologic patterns of pediatric pulmonary blastomycosis, and correlate the radiologic patterns with patient age. MATERIALS AND METHODS. Patients 0–18 years old with pulmonary blastomycosis who underwent chest imaging from 2005 to 2016 were included in this study. The following data were collected: age, sex, clinical information, and imaging findings including presence of extrapulmonary involvement and scarring on follow-up examinations. Concordance between radiography and CT was analyzed. RESULTS. Thirty-six patients (28 boys and 8 girls) ranging in age from 3 months to 17 years (mean, 10.5 years) were identified. Consolidation was found in 94.4% of patients and was unilateral in 76.5% of cases and bilateral in 23.5%. Upper (70.6%) and middle (47.1%) lobes were more frequently involved. Air bronchograms were identified in 76.5% of patients with consolidations, masslike consolidation was found in 55.9%, cavitation in 38.2%, and bubbly pattern (i.e., multiple small cavities) in 32.4%. In all patients younger than 5 years, consolidations involved multiple lobes. In 67.6% of patients, consolidations were associated with the following additional pulmonary or pleural abnormalities: pulmonary nodules (50% of patients), diffuse patchy opacification (26.5%), reticulonodular pattern (41.2%), atelectasis (5.9%), pleural effusion (20.6%), and hilar lymphadenopathy (23.5%). Pulmonary scarring was found in 70.4% of patients. Five patients had extrapulmonary involvement. The concordance between radiography and CT was excellent for location and extension of consolidation and diagnosis of cavitation, bubbly pattern, and nodules. CONCLUSION. The most common pattern of lung involvement from pulmonary blastomycosis in our series was a combination of consolidations with bilateral lung nodules and reticulonodular opacification.
关键词： chest radiography,imaging patterns,pediatric pulmonary blastomycosis,different age groups,chest CT
更新于2025-09-23 15:23:52
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Virtual subpixel approach for single-mask phase-contrast imaging using Timepix3
摘要： X-ray phase contrast imaging provides a method to distinguish materials with similar density and effective atomic number, which otherwise would be difficult using conventional X-ray absorption contrast. In recent years, multiple methods have been developed to acquire X-ray phase contrast images using incoherent laboratory sources. The single mask edge illumination setup has been demonstrated as a possible candidate for large scale applications due to its relaxed restrictions on longitudinal coherence and mask alignment, and for its ability to do bi-directional phase contrast images in a single sample exposure. Unfortunately, the single mask edge illumination setup's refraction sensitivity, and thereby signal to noise, is limited by detector artifacts. Furthermore, it requires multiple exposures to perform dark-field imaging, a method that enables imaging of micro-structures smaller than the image resolution. We propose using an Advapix detector with Timepix3 pixel-readout chip in a single mask imaging setup to improve signal to noise ratio in phase contrast images. This is achieved using the Timepix3 chip's ability to simultaneously acquire fast time of arrival and time over threshold measurement of single photon events, which enables sub-pixel identification of individual photons. In this paper, we demonstrate that signal to noise ratio can be improved by at least 67 ± 5 % using subpixel identification of single photons compared to conventional acquisitions methods. Thereby the required sample dose can be reduced considerably. This shows that there is a great potential in using Timepix3 chip to improve x-ray phase contrast imaging. Further, the results indicate the possibility for dark field imaging in a single sample exposure using Timepix3 in a single mask edge illumination setup.
关键词： X-ray detectors,X-ray radiography and digital radiography (DR),Data processing methods,Inspection with x-rays
更新于2025-09-23 15:22:29
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Is there still a role for abdominal plain X-ray in acute abdomen?
摘要： The imaging workup of patients with acute abdominal pain still starts with abdominal X-ray in several clinical settings and facilities. Unfortunately, conventional plain film is of limited utility if performed as a routine investigation. Abdominal radiography is valuable only in patients with suspected perforated viscus and large bowel obstruction. Ultrasound is mostly valuable in the vast majority of abdominal pain presentations, whereas computed tomography scan should be considered as second level test.
关键词： Bowel occlusion,Plain radiography,Abdominal X ray,Pneumoperitoneum,Acute abdomen
更新于2025-09-23 15:22:29
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Estimation of Zero-Frequency Noise Power Density in Digital Imaging
摘要： Noise power spectrum (NPS) at zero frequency can efficiently represent noise properties of imaging systems. However, estimations of zero-frequency NPS are susceptible to distortion due to several factors leading to low-estimate precisions. In this letter, a high-precision estimate algorithm for zero-frequency NPS is proposed. The proposed estimate is a compensated sum of signal variances and covariances. The accuracy and precision of the proposed approach were first observed with synthetic data. A flat panel radiography detector based on CsI(Tl)-scintillator was then used to experimentally observe the improved estimate precision of the proposed algorithm. Experiment results showed that the estimation precision was improved to 14 times compared to that of the conventional method.
关键词： Radiography imaging,sample mean of periodograms,zero-frequency noise power density
更新于2025-09-23 15:22:29
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Can adaptive post-processing of storage phosphor plate panoramic radiographs provide better image quality? A comparison of anatomical image quality of panoramic radiographs before and after adaptive processing
摘要： Objective: The objective of the present study was to study the effect of adaptive image processing on the visibility of anatomical structures in storage phosphor plate (SPP) panoramic images. Materials and methods: Three hundred SPP panoramic X-ray radiographs of children and adolescents were used. The radiographs were post-processed using general operator processor (GOP) technology, resulting in both a standard-processed and a GOP-processed radiograph. Four specialists in dental radiology compared the structural image quality of all standard-processed and GOP-processed panorama images for six anatomical structures, using a six-point scale for visual grading characteristics (VGC) analysis. Results: For three of the anatomic structures – the root canal space of the mandibular left first premolar, mandibular canal left side and periodontal ligament space of the mandibular right first molar – there was a statistically significant difference to the GOP’s advantage. For the three remaining structures – dentino-enamel junction of the maxillary right first molar, crista alveolaris of the mandibular left molar area and floor of maxillary sinus right side – no significant difference between standard processing and GOP processing was obtained. Conclusions: The study demonstrates that it is possible to improve the quality of SPP radiographs and the visibility of anatomical structures by using the GOP technique. Manufacturers’ image-processing programs can be further developed, as there is a possibility of improving the diagnostic content of an image with external processing.
关键词： digital,storage phosphor plate,radiographic image enhancement,radiography,panoramic,Adaptive processing,dental
更新于2025-09-23 15:22:29