Purpose
Chronic obstructive pulmonary disease (COPD) affects ∼200 million people worldwide. We propose two‐dimensional (2D) dual‐energy (DE) x‐ray imaging of lung structure and function for the ...assessment of COPD, and investigate the resulting image quality theoretically.
Methods
We investigated xenon‐enhanced DE (XeDE) radiography for functional imaging of COPD and unenhanced DE radiography for structural imaging of COPD. We modeled the ability of human observers to detect ventilation defects in XeDE images and emphysema in (unenhanced) DE images using the detectability index (d′) as a figure of merit. We accounted for the extent of emphysematous destruction and functional impairment as a function of disease severity, defect/lesion contrast, spatial resolution, x‐ray scatter, quantum noise, anatomic noise, and the efficiency of human observers. Whether or not disease was detectable was determined based on a detectability threshold of two. For (unenhanced) DE imaging of emphysema, we compared detectability with that of single‐energy (SE) imaging. Models of signal and noise were compared to published data.
Results
Models of signal and noise agreed well with published data, and model predictions of the detectability of emphysema by SE radiography were consistent with poor sensitivity (i.e., d′<1) to mild to moderate COPD but moderate sensitivity (i.e., d′>1.5) to severe COPD. The detectability of emphysema by DE radiography was greater than that of SE radiography, but did not cross the threshold of detectability for mild to moderate COPD. The detectability index for XeDE imaging exceeded the detectability threshold for mild, moderate, and severe COPD.
Conclusions
Dual‐energy radiography may offer modest improvements in the detection of emphysema relative to SE imaging, but will unlikely enable detecting mild and moderate COPD. However, XeDE radiography may enable detection of functional abnormalities associated with mild, moderate and severe COPD at x‐ray exposures typical of those used in conventional chest radiography, thus warranting further investigation as a low‐dose, low‐cost alternative to CT‐ and MRI‐based approaches for functional imaging of COPD.
In 2007, the International Commission on Radiological Protection (ICRP) revised estimates of the radiosensitivity of tissues including those in the maxillofacial region. The authors conducted a study ...to reassess patients' risk related to common dental radiographic exposures using the 2007 ICRP recommendations.
The authors used a tissue-equivalent head phantom to measure dose. They calculated effective doses by using both 1990 and revised 2007 ICRP recommendations. Effective dose is a calculation that takes into consideration the different sensitivities of organs to long-term effects from ionizing radiation. It is the preferred method for comparing doses between different types of exposures.
Effective doses (per the 2007 ICRP) in microsieverts were as follows: full-mouth radiographs (FMX) with photo-stimulable phosphor (PSP) storage or F-speed film with rectangular collimation, 34.9 microSv; four-image posterior bitewings with PSP or F-speed film with rectangular collimation, 5.0 microSv; FMX using PSP or F-speed film with round collimation, 170.7 microSv; FMX with D-speed film and round collimation, 388 microSv; panoramic Orthophos XG (Sirona Group, Bensheim, Germany) with charge-coupled device (CCD), 14.2 microSv; panoramic ProMax (Planmeca, Helsinki, Finland) with CCD, 24.3 microSv; posteroanterior cephalogram with PSP, 5.1 microSv; and lateral cephalogram with PSP, 5.6 microSv. These values are 32 to 422 percent higher than those determined according to the 1990 ICRP guidelines.
Although radiographs are an indispensable diagnostic tool, the increased effective doses of common intraoral and extraoral imaging techniques are high enough to warrant reconsideration of means to reduce patients' exposure.
Clinicians can reduce patients' dose substantively by using digital receptors or F-speed film instead of D-speed film, rectangular collimation instead of round collimation and radiographic selection criteria.
Abstract
Roentgen’s photographs with the “new kind of rays” triggered a worldwide storm of enthusiasm in all social circles. It was a stroke of luck that the photographic dry plates available to him ...were also sensitive to invisible X-rays. The discovery, research and utilization of X-rays are based on methods for making them visible, from fluorescent screens to photographic plates and digital X-ray detectors. From this point of view, this paper aims to outline the 125-year success story of X-ray imaging from its discovery to the recent development of photon-counting detectors. The scientific-historical view during the transition from the 19
th
to the 20
th
century reveals an impressive period of profound scientific and social upheaval in which revolutionary discoveries and technological developments led to enormous progress in medicine. The cross-fertilization of physics and medicine and their combination with inventiveness, engineering and entrepreneurial spirit created the impressive possibilities of today’s imaging diagnostics. This contribution accompanies the Roentgen Lecture the author gave on November 13, 2020 in Roentgen’s birth house as part of its inauguration and the closing ceremony of the 101
st
Congress of the German Roentgen Society in Remscheid-Lennep.
Key Points:
The development of computed tomography was a milestone in the methodological advancement of imaging with X-rays.
In the detector pixel invisible X-rays are converted into digital electrical impulses, which the computer uses to create images.
Photon-counting detectors could have significant diagnostic advantages for clinical applications.
Citation Format
Schlemmer H, The Eye of the CT Scanner: The story of learning to see the invisible or from the fluorescent screen to the photon-counting detector. Fortschr Röntgenstr 2021; 193: 1034 – 1048
Zusammenfassung
Röntgens Fotografien mit der „neuen Art von Strahlen“ lösten einen weltweiten Begeisterungssturm in allen gesellschaftlichen Kreisen aus. Dabei war es ein Glücksfall, dass die ihm zu Verfügung stehenden fotografischen Trockenplatten auch für die unsichtbaren X-Strahlen empfindlich waren. Entdeckung, Erforschung und Nutzbarmachung von Röntgenstrahlen beruhen auf Methoden zur deren Sichtbarmachung, vom Fluoreszenzschirm über die Fotoplatte bis hin zum digitalen Röntgendetektor. Aus diesem Blickwinkel heraus möchte diese Arbeit die 125-jährige Erfolgsgeschichte der Röntgenbildgebung von der Entdeckung bis zur jüngsten Entwicklung photonenzählender Detektoren skizzieren. Die wissenschaftshistorische Betrachtung am Übergang des 19. zum 20. Jahrhundert offenbart eine eindrucksvolle Zeit tiefgreifender wissenschaftlicher und gesellschaftlicher Umbrüche, in der revolutionäre Entdeckungen und technologische Entwicklungen zu gewaltigen Fortschritten der Medizin führten. Die gegenseitige Befruchtung von Physik und Medizin und deren Verquickung mit Erfindergeist, Ingenieurskunst und unternehmerischem Geschick schufen die eindrucksvollen Möglichkeiten der bildgebenden Diagnostik von heute. Diese Arbeit begleitet die Röntgenvorlesung, die der Autor am 13. November 2020 im Röntgen-Geburtshaus im Rahmen von dessen Eröffnung sowie des feierlichen Abschlusses des 101. Deutschen Röntgenkongresses in Remscheid-Lennep gehalten hat.
Kernaussagen:
Die Entwicklung der Computertomografie markiert einen Meilenstein der methodischen Weiterentwicklung der Bildgebung mit Röntgenstrahlen.
Im Detektorpixel werden die unseren Sinnen unzugänglichen Röntgenstrahlen in digitale elektrische Impulse umgewandelt, aus denen der Computer die Bilder errechnet.
Photonenzählende Röntgendetektoren lassen deutliche diagnostische Vorteile für klinische Anwendungen erwarten.
Zitierweise
Schlemmer H, The Eye of the CT Scanner: The story of learning to see the invisible or from the fluorescent screen to the photon-counting detector. Fortschr Röntgenstr 2021; 193: 1034 – 1049
Panoramic radiology systems are currently being used in more practices than at other any time in the past. The practitioner now has decisions to make regarding detector technology selection for image ...acquisition and must remain informed about appropriate usage. This book is applicable to all panoramic dental images and equipment. It approaches panoramic radiology usage in the context of general and specialty applications.
To investigate the current clinical applications and diagnostic performance of artificial intelligence (AI) in dental and maxillofacial radiology (DMFR).
Studies using applications related to DMFR to ...develop or implement AI models were sought by searching five electronic databases and four selected core journals in the field of DMFR. The customized assessment criteria based on QUADAS-2 were adapted for quality analysis of the studies included.
The initial electronic search yielded 1862 titles, and 50 studies were eventually included. Most studies focused on AI applications for an automated localization of cephalometric landmarks, diagnosis of osteoporosis, classification/segmentation of maxillofacial cysts and/or tumors, and identification of periodontitis/periapical disease. The performance of AI models varies among different algorithms.
The AI models proposed in the studies included exhibited wide clinical applications in DMFR. Nevertheless, it is still necessary to further verify the reliability and applicability of the AI models prior to transferring these models into clinical practice.
Automatic detection of casting defects on radiography images is an important technology to automatize digital radiography defect inspection. Traditionally, in an industrial application, conventional ...methods are inefficient when the detection targets are small, local, and subtle in the complex scenario. Meanwhile, the outperformance of deep learning models, such as the convolutional neural network (CNN), is limited by a huge volume of data with precise annotations. To overcome these challenges, an efficient CNN model, only trained with image-level labels, is first proposed for detection of tiny casting defects in a complicated industrial scene. Then, in this article, we present a novel training strategy which can form a new object-level attention mechanism for the model during the training phase, and bilinear pooling is utilized to improve the model capability of detecting local contrast casting defects. Moreover, to enhance the interpretability, we extend class activation maps (CAM) to bilinear CAM (Bi-CAM) which is adapted to bilinear architectures as a visualization technique to reason about the model output. Experimental results show that the proposed model achieves superior performance in terms of each quantitative metric and is suitable for most actual applications. The real-time defect detection of castings is efficiently implemented in the complex scenario.
Disorders of the lungs such as chronic obstructive pulmonary disease (COPD) are a major cause of chronic morbidity and mortality and the third leading cause of death in the world. The absence of ...sensitive diagnostic tests for early disease stages of COPD results in under-diagnosis of this treatable disease in an estimated 60-85% of the patients. In recent years a grating-based approach to X-ray dark-field contrast imaging has shown to be very sensitive for the detection and quantification of pulmonary emphysema in small animal models. However, translation of this technique to imaging systems suitable for humans remains challenging and has not yet been reported. In this manuscript, we present the first X-ray dark-field images of in-situ human lungs in a deceased body, demonstrating the feasibility of X-ray dark-field chest radiography on a human scale. Results were correlated with findings of computed tomography imaging and autopsy. The performance of the experimental radiography setup allows acquisition of multi-contrast chest X-ray images within clinical boundary conditions, including radiation dose. Upcoming clinical studies will have to demonstrate that this technology has the potential to improve early diagnosis of COPD and pulmonary diseases in general.
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