X-ray Diagnostic Methods Research Articles

FEATURES OF DIAGNOSTIC SURGICAL TREATMENT OF COMPLICATIONS OF NECROTIC PANCREATITIS

Summary. The aim of the study. On the basis of the conducted research, optimize the program of comprehensive diagnosis of complications of necrotic pancreatitis and the principles of surgical treatment of infected pancreatic necrosis. Materials and methods. Analysis of diagnosis and treatment of 496 patients with acute pancreatitis was performed. Necrotic forms of purulent pancreatitis were diagnosed in 178 (35.9%) patients. Clinical, biochemical and bacteriological methods of laboratory diagnostics were carried out upon admission to the hospital and every 2-5 days depending on the severity of their condition. Ultrasound and endoscopic examination were performed for diagnostic and therapeutic purposes. X-ray diagnostic methods were widely used: X-ray of the stomach and duodenum with barium, fistulography, puncture pancreatocystography. Diagnostic scales were used to study the severity of the course of acute pancreatitis and the prognosis of the disease. The obtained data were processed using statistical methods. Results. The use of modified surgical tactics in the treatment of infected forms of pancreatic necrosis made it possible to reduce postoperative mortality to 14.3%. Conclusions. Indications for early surgical interventions in pancreatic necrosis are biliary pathology and the impossibility of excluding other acute pathology from the abdominal organs, as well as the progression of pancreatic necrosis with significant deterioration of the patient’s general condition. The principle of surgical treatment of infected pancreatic necrosis is to perform surgical intervention in relatively late (more than 20 days from the onset of the disease), after suppression of the systemic inflammatory reaction and possible sequestration of necrosis centers. In surgical treatment, the method of completing the operation for necrotic pancreatitis and its purulent-necrotic complications is closed lavage, which is more effective in the treatment of localized forms of purulent-necrotic pancreatitis; the method of programmed relaparotomy - for common forms of purulent complications of intra-abdominal localization and widespread purulent peritonitis; the method of treatment through a «controlled» laparostomy is effective in the treatment of large retroperitoneal phlegmons.

FEATURES OF DIAGNOSTIC SURGICAL TREATMENT OF COMPLICATIONS OF NECROTIC PANCREATITIS

Summary. The aim of the study. On the basis of the conducted research, optimize the program of comprehensive diagnosis ofcomplications of necrotic pancreatitis and the principles of surgicaltreatment of infected pancreatic necrosis.Materials and methods. Analysis of diagnosis and treatment of496 patients with acute pancreatitis was performed. Necrotic formsof purulent pancreatitis were diagnosed in 178 (35.9%) patients.Clinical, biochemical and bacteriological methods of laboratorydiagnostics were carried out upon admission to the hospital and every2-5 days depending on the severity of their condition. Ultrasoundand endoscopic examination were performed for diagnostic andtherapeutic purposes. X-ray diagnostic methods were widely used:X-ray of the stomach and duodenum with barium, fistulography,puncture pancreatocystography. Diagnostic scales were used to studythe severity of the course of acute pancreatitis and the prognosis of thedisease. The obtained data were processed using statistical methods.Results. The use of modified surgical tactics in the treatment ofinfected forms of pancreatic necrosis made it possible to reducepostoperative mortality to 14.3%.Conclusions. Indications for early surgical interventions inpancreatic necrosis are biliary pathology and the impossibility ofexcluding other acute pathology from the abdominal organs, as wellas the progression of pancreatic necrosis with significant deteriorationof the patient’s general condition.The principle of surgical treatment of infected pancreatic necrosisis to perform surgical intervention in relatively late (more than 20days from the onset of the disease), after suppression of the systemicinflammatory reaction and possible sequestration of necrosis centers.In surgical treatment, the method of completing the operationfor necrotic pancreatitis and its purulent-necrotic complications isclosed lavage, which is more effective in the treatment of localizedforms of purulent-necrotic pancreatitis; the method of programmedrelaparotomy - for common forms of purulent complications of intraabdominallocalization and widespread purulent peritonitis; themethod of treatment through a «controlled» laparostomy is effectivein the treatment of large retroperitoneal phlegmons.

Multivariate analysis of Raman spectra for discriminating human collagens: In vitro identification of extracellular matrix collagens produced by an osteosarcoma cell line

BackgroundThe NHS spends £4.3 billion annually to address musculoskeletal conditions, encompassing age-related bone disorders like osteoarthritis and osteoporosis. Traditional X-ray diagnostic methods are commonly employed for bone disorder diagnosis, primarily assessing gross anatomical bone structure changes. However, these methods are unable to identify subtle biochemical alterations within the bone. More detailed information, particularly about protein changes, may lead to enhanced diagnostics and treatment. Raman spectroscopy is a non-invasive, laser-based technique capable of detecting changes in the collagen component of bone. Despite its long-standing application in discerning mineral and protein changes within bone, there is limited evidence on Raman spectral signatures of purified human collagens and their differentiation. This study aimed to test the hypothesis that Raman spectroscopy could detect different types of collagen in the human body. ResultsA Raman microspectrometer with a 785 nm laser was used to measure unmineralized human collagens types I – VI and collagenous extracellular matrix (ECM) secreted by MG63 osteoblast-like cells. The results demonstrated the efficacy of Raman spectroscopy and subsequent multivariate analysis in distinguishing human collagen types I – VI. This implies that Raman spectroscopy, coupled with multivariate analysis, can identify pure human collagens and offers reference spectra similar to natural human collagen in the bone extracellular matrix. SignificanceThis study establishes Raman spectroscopy as a tool for identifying and characterizing human collagens, aiding in the diagnosis of connective tissue disorders. The creation of a spectral reference library for pure human collagen types I – VI holds potential for medical diagnostics, analytical chemistry, and materials science applications.

The First Cranial Trepanation Find in a Meotian Burial Ground (Starokorsunskiy Settlement No. 2, Krasnodar Region)

A young woman’s skeleton dating back to the Meotian archaeological culture was studied during the investigation of the paleoanthropological series of the burial ground of the Starokorsunsky settlement No. 2. The burial ground is located in the Krasnodar Territory and is dated to the 4th century BC – 2nd century AD, while the burial under discussion dates back to the 2nd century BC – 2nd century AD. A trepanation hole with signs of healing was found on the skull of a young female of 17–25 years of age. In order to describe the pathological changes recorded on the cranial vault recommendations applied in modern paleoanthropology were used. Differential diagnosis was performed using descriptive macroscopic and X-ray diagnostic methods. It was possible to establish that the trepanation hole was made at least several years before the death of the individual. We suggested that the reason for the operation could be early synostosis of the skull sutures, and this manipulation was designed to reduce intracranial pressure and headaches caused by it. The article discusses the likely origins of medical skills for surgical manipulation. It is concluded that so far the data obtained do not allow us to speak unequivocally about the acquisition of medical knowledge by Meots from residents of the Asian Bosporus or from the Sarmatian environment.

Imaging of bones dysbarogenic changes in navy divers

The number of diving descents in the world is steadily growing, as is the complexity of the work performed under conditions of increased environmental pressure. Also, in order to increase efficiency and expand the range of tasks performed, the intensity, depth of dives and the time divers spend in hyperbaric conditions are increasing. These factors contribute to an increase in the number of diving pathologies, including damage to the skeletal bones of dysbarogenic genesis. X-ray diagnostic methods used during annual medical examinations of divers do not always allow the detection of dysbarogenic changes in the bones; in addition, the clinical manifestations of this pathology do not have obvious specificity. In this regard, it can be assumed that the occurrence of this pathology among divers has not been reliably established to date. This article is devoted to a review of the literature on the possibilities of radiodiagnosis of dysbarogenic changes in skeletal bones in specialists whose work involves being in conditions of high environmental pressure. The article highlights the results of a literature review of English-language and Russian-language publications presented in the databases of PubMed and scientific electronic libraries of Russia (eLIBRARY.RU and CYBERLENINKA.RU). In order to determine the optimal methods of radiation diagnostics, the etiological and pathogenetic aspects of the development of dysbarogenic degenerative and necrotic changes in the bones of the skeleton, as well as the experience of scientists in determining the corresponding radiation semiotics, were analyzed. Considering that the worst manifestation of bone pathology of dysbarogenic origin is dysbaric (aseptic) osteonecrosis, we studied the literature on the issues of its clinical and instrumental diagnosis. One of the directions in scientific research was the work of authors exploring the possibilities of early instrumental diagnosis of changes in bone tissue, in particular the possibilities of magnetic resonance imaging in the diagnosis of dysbaric osteonecrosis. In addition, data on modern x-ray methods were analyzed, which may be promising as a screening diagnosis of dysbarogenic degenerative and necrotic changes in the bones of the skeleton.

Clinical experience evaluation and comparative analysis of the results of X-ray diagnostic methods in patients with traumatic fractures of the lower jaw

Clinical experience evaluation and comparative analysis of the results of X-ray diagnostic methods in patients with traumatic fractures of the lower jaw

Synthesis and Electronic Structure of Bimetallic AuFe Nanocomposites

Au, Fe, and AuFe nanoparticles were obtained by metal vapor synthesis using acetone as the dispersion medium. The composition and electronic structure of the particles were studied by TEM, SEM, XPS, XANES, and EXAFS. The Au and Fe particles with average diameters of 5.3 and 1.8 nm, respectively, were obtained. According to X-ray diagnostic methods, gold was in the main Au0 state, and the Au+ and Au3+ states are present in small amounts while iron existed as mixture of non-stoichiometric oxides with states close to Fe2+ and Fe3+. Bimetallic nanoparticles were solid solutions with a disordered structure and Au–Fe–O and Au–O–Fe bonds. A carbon-containing shell was detected for all types of metal particles. The obtained materials may be promising for the development of improved antimicrobial agents and new methods for treating cancer diseases.

Case of acute recurrent myocardial infarction in a child

Information on the essential aspects of prevalence, etiology and pathogenesis of coronary heart disease, which is the leading cause of death in the world, is given in this article. It is emphasized that the incidence of ischemic coronary events is the result of a complex sequence of pathogenetic links, which involves the formation of atherosclerotic lesions and destabilization as the primary provoking factor. Purpose - the attraction of the medical community attention to the problem of ischemic heart disease in children. A clinical case of recurrent myocardial infarction in a child who was examined and treated at the MNPE «Ivano-Frankivsk Regional Children’s Clinical Hospital of the Ivano-Frankivsk Regional Council», is described here. The key points of the patient’s complaints, anamnesis of life and this disease are described, the data of the objective condition at the hospitalization and during dynamic observation of the child, which showed the signs of left ventricular overload, coronary blood flow disorder, dilatation of the left heart ventricles, decreased left ventricular contractility. The data of the main indices of laboratory and instrumental methods of research, including X-ray diagnostic methods, performed not only on the basis of the department, but also in the Scientific-Practical Medical Center of Pediatric Cardiology and Cardiac Surgery of the Ministry of Health of Ukraine (Kyiv). The treatment of this clinical case in the child is described in this article. The data of dynamic observation are given. The discussion and conclusions emphasize the problem of coronary insufficiency in pediatrics, which requires clinical understanding, the choice of the correct diagnostic algorithm and qualified medical care. The study was performed in accordance with the principles of the Declaration of Helsinki. Informed consent of the child’s parents was obtained for the research conduction. No conflict of interests was declared by the authors.

Decision Making Support System for the Diagnostics of the Cardiovascular System Pathologies by the X-ray Images of the Chest

The lack of universal (generalized) data sets, as well as the lack of annotated data, creates the need to study the possibilities of neural network approaches for specific data sets. The importance of building algorithms for detecting extrapulmonary pathologies on chest X-ray images is dictated by the great social significance of many diseases of this group (for example, cardiovascular diseases), given the availability of such images, due to the widespread use of minimally invasive and relatively cheap X-ray diagnostic methods. One of the most impor tant issues in solving the problems of automating the classification of medical images is data preparation. As a result of work on the image base, the performance of the final algorithm has been increased from 75 to 95 %. The processing of the entire volume of the obtained images and their diagnostics for a wide list of pathologies are difficult for medical institutions because of the limited resources. In this regard, it is advisable to use the automation of segmentation and recognition processes, which even at the first stages of development of the technology makes it possible to redistribute the attention of doctors, focusing on potentially pathological cases and returning attention to cases mistakenly identified as non-pathological.

Рентгеноанатомические параллели в структурном оформлении костных челюстных каналов у овец

The article presents X-ray anatomical parallels of the structural design of the bone jaw canals of sheep. The studies were carried out at the Department of Anatomy and Histology of Animals named after. Professor A. F. Klimov of Moscow State Academy of Veterinary Medicine and Biotechnology – MVA named after K. I. Skryabin. The object of research was sexually mature sheep of the Romanov breed (n=20) without pronounced signs of pathology. Skulls and plain radiographs (n=20) served as the material for the study. The study used a set of methods, including: anatomical macroand micro-preparation and macromorphometry, also performed a survey radiography of the bone skeleton of the head in the studied sheep on the apparatus, followed by decoding of the information received and morphometry, followed by statistical processing of the obtained digital data according to generally accepted methods. Analysis of the obtained linear morphometric parameters of the jaw bones made it possible to conclude that the parameters of the upper jaw are inferior in terms of their numerical values to those of the lower one, while there were no significant differences between their right and left halves. In a comparative analysis of the morphometric and X-ray parameters of the skull, no significant differences were found, which indicates the high information content of X-ray diagnostic methods in assessing the morphological and functional components of the head organs. The results obtained are the basis for the development of new methods of treatment strategy and tactics for extirpation of teeth, as well as for local anesthesia of the trigeminal nerve during surgical interventions in veterinary and experimental dentistry.

Phase imaging of irradiated foils at the OMEGA EP facility using phase-stepping X-ray Talbot–Lau deflectometry

Abstract Diagnosing the evolution of laser-generated high energy density (HED) systems is fundamental to develop a correct understanding of the behavior of matter under extreme conditions. Talbot–Lau interferometry constitutes a promising tool, since it permits simultaneous single-shot X-ray radiography and phase-contrast imaging of dense plasmas. We present the results of an experiment at OMEGA EP that aims to probe the ablation front of a laser-irradiated foil using a Talbot–Lau X-ray interferometer. A polystyrene (CH) foil was irradiated by a laser of 133 J, 1 ns and probed with 8 keV laser-produced backlighter radiation from Cu foils driven by a short-pulse laser (153 J, 11 ps). The ablation front interferograms were processed in combination with a set of reference images obtained ex situ using phase-stepping. We managed to obtain attenuation and phase-shift images of a laser-irradiated foil for electron densities above ${10}^{22}\;{\mathrm{cm}}^{-3}$ . These results showcase the capabilities of Talbot–Lau X-ray diagnostic methods to diagnose HED laser-generated plasmas through high-resolution imaging.

Analysis of the Advances of RDC 330/19 in relation to Ordinance 453/98 under the Radiation Protection Focus

Almost twenty years after the publication of Ordinance 453, the National Health Surveillance Agency (ANVISA) approved the Collegiate Board Resolution 330 (RDC 330), which establishes the basic guidelines for Radiation Protection (RP) in diagnostic and interventional radiology and regulates the use of X-ray diagnostic methods throughout the national territory. Therefore, when observing the radiodiagnostic service and its changes suffered in recent decades, the addition of new modalities is noticeable, as well as changes in the service flow, brought about as a result of the advancement of new technologies. The RDC 330 came with several changes even in its format: a document with the basic guidelines for radioprotection and several Normative Instructions (INs) - one for each technology in diagnostic imaging. Among the INs, IN58 and IN59 can be mentioned, which provide for sanitary requirements for quality assurance and safety in ultrasound and magnetic resonance systems, respectively, which now makes quality control mandatory. The RDC 330 and its respective IN were developed to meet all these needs, contextualizing the principles already established for the elevation of the RP culture and diagnostic quality. Therefore, the implementation of RDC 330 is defended, in view of the need for agile adaptation that can ensure improvements in the quality of imaging services, dose optimization and in the quality control of radiodiagnostic equipment, promoting the safety of patients, population and workers exposed to ionizing radiation.

The Role of Vascular-Platelet Hemostasis Disturbances in the Genesis of Respiratory Failure in Patients with COVID-19

The objective: to study the relationship between markers of imbalance in the platelet-vascular hemostasis system and lung damage and disease outcome in patients with COVID-19.Subjects and Methods: the study included 225 patients with the confirmed diagnosis of moderate, severe and extremely severe COVID-19. In all patients, lung damage was confirmed using computed and X-ray diagnostic methods. We studied the concentration of von Willebrand factor (vWF), activity of metalloproteinase ADAMTS-13, concentration of homocysteine, endothelin-1, thrombomodulin and the number of platelets and changes in these parameters on the 1st, 3–5th and 7–10th days from the admission to the intensive care unit (ICU). In deceased patients (n = 106), lung specimens were collected to assess the nature of morphological changes.Results. It was determined that by the 7–10th days with a lethal outcome of the disease, there was a statistically significant increase in the concentration of vWF by 22.2% (p = 0.0225), the vWF/ADAMTS-13 ratio by 2 times (p = 0.0408) and decrease in the platelet count by 52% (p = 0.0008) versus the initial stage of the study. In all the deceased, the morphological picture of lung tissue damage was characterized by destruction of alveolocytes, proliferation of connective tissue, cellular infiltration, plethora of capillaries, parietal erythrocyte thrombi in the lumen of capillaries, arterioles and venules, and obstructive erythrocyte thrombi in the lumen of vessels of lung microcirculation.Conclusion. The study showed that a possible cause of thrombosis in the lumen of vessels of lung microcirculation in the case of a lethal outcome of COVID-19 might be a primary imbalance in the vascular-platelet hemostasis characterized by a significant increase in the concentration of the vWF factor, the vWF/ADAMTS-13 ratio and a decrease in the number (consumption) of platelets by the 7–10th day of the disease versus the initial stage of the study.

Nondestructive Elemental Diagnostics of the Fuel-Rod Cladding Surface by the Ion-Beam and X-Ray Analytical Methods

The characteristics of the production technology for fuel rod cladding oriented to its application for water-moderated water-cooled power reactors with a coolant temperature of 300−350°C are presented. Possible directions for the modification of the cladding surface are proposed. The methodological background for the diagnostics of materials based on the ion-beam and X-ray diagnostic methods is discussed. Using this diagnostics, it is possible to characterize the parameters of the inner and outer surfaces of the fuel-rod cladding without changing its form. Experimental data are presented, which demonstrate the efficiency of the proposed analytical complex for characterizing the surface layers of fuel-rod cladding.

VATS resection of basal pyramid segments in sequestration of the left lower lobe

Lung sequestration is a congenital malformation represented by a non-functioning pulmonary parenchyma supplied via an aberrant artery of systemic circulation. This malformation makes up 1-6% of all congenital lung abnormalities. In 1946, Pryce M.D. proposed the term «lung sequestration» for the disease first described by the Austrian pathologist C. Rokitansky in 1856. Lung sequestration becomes quire common due to development and availability of X-ray diagnostic methods. An aberrant artery can arise from the great vessels (thoracic and abdominal aorta) and smaller arteries (coronary, intercostal arteries). To date, there are 2 forms of lung sequestration (intralobar and extralobar). We report one of the options for surgical treatment of lung sequestration.

Modern possibilities of the urine steroid profile testing applying for the adrenocortical cancer diagnosis

BACKGROUND: X-ray diagnostics methods are important in detection of adrenal neoplasms malignant nature. The sensitivity and specificity of these methods are high enough. However the hormonal tests are also necessary to make an accurate clinical diagnosis with the high diagnostic efficiency of modern X-ray methods for adrenal tumors diagnosing. The urine steroid profile violations are detected with the adrenal glands various pathologies (primary hyperaldosteronism, hypercorticism, congenital hyperplasia of the adrenal cortex and adrenocortical cancer). Urine steroid profile tests in patients with diagnosed adrenal neoplasms are intended primarily to confirm or refute the adrenocortical cancer risk. At the same time in the medical community to date there are a number of disagreements accumulated regarding the accuracy and significance of the urine steroid profile tests.
 AIMS: The study aims to determine the urine steroid profile determination accuracy limits for the adrenocortical cancer diagnosis.
 MATERIALS AND METHODS: In total 62 samples were tested for urine steroid profile by gas chromatography-mass spectrometry. 58 patients had morphologically confirmed adrenal neoplasms. The study was blind prospective. To increase the study accuracy the 30 patients with adrenocortical adenomas (n = 17) and adrenocortical cancer (n = 13) were selected out of 58 tested persons. The sensitivity, specificity and accuracy of the urine steroid profile were determined in order to assess information content of such method for the adrenocortical carcinoma diagnosis.
 RESULTS: The possibilities of the urine steroid profile determining for the adrenocortical cancer diagnosis are estimated. The method sensitivity was 46.2%, specificity and accuracy were 70.6% and 60% respectively. The most reliable of adrenocortical cancer markers were tetrahydro-11-deoxycortisol and dehydroepiandrosterone (38.5% of cases) increasing concentrations.
 CONCLUSIONS: The present study demonstrates relatively low diagnostic efficacy of the urine steroid profile as a primary diagnostic method for adrenocortical cancer determining. This is especially evident in comparison with X-ray diagnostic methods. The technique interpretation is complex and accessible only to specialists with extremely high qualifications. Such fact complicates the distribution and widespread use in clinical practice of this testing method. At the same time the urine steroid profile determination in the future (after additional study) may be apply as an auxiliary diagnostic method which in some cases determines the treatment tactics for patients undergoing adrenocortical cancer adrenalectomy treatment.KEYWORDS: dPheochromocytoma; intraoperative hemodynamic instability; laparoscopic adrenalectomy; Endovascular embolization of preoperative; сase report.

TREATMENT OF SEVERE RECTAL INJURY WITH DAMAGE TO THE EXTERNAL SPHINCTER IN CHILDREN

Material and methods. Over 30 years, under supervision there were 6 children of 3 and 18 years, with severe injuries of the rectum and anus. In the diagnosis there was used history, examination, catheterization of the bladder, ultrasound, vaginal and rectoscopy, x-ray diagnostic methods. Results and discussion. Two 3 and 6 years old girls were raped. All had damage not only to the perineum and vagina, but also to the vaginal-rectal septum, rectum, and sphincter. In one child, damage to the rectum and anus occurred during surgery for rectal atresia. Surgical intervention was performed by perineal access. In three adolescents, an injury to the pelvic organs with damage to the rectum, anus, and pelvic bones was a consequence of traffic accidents. Two of them died from traumatic brain injury. The author presents three clinical observations. Conclusion. Combined injuries of the rectum and sphincter are serious injuries. Signs of shock, internal bleeding, open and closed fractures may come to the fore. Assistance to injured children should be carried out in specialized institutions. The main method of the treatment of severe injuries of the sphincter of the rectum is the closure of the sphincter defect

Challenges of x-ray spectroscopy in investigations of matter under extreme conditions

Advanced X-ray spectroscopic methods provide unique and critical data to study matter under extreme environmental conditions induced by high-intensity and high-energy lasers. The aim of this paper is to contribute to a contemporary discussion of the role of X-ray spectroscopy in the investigation of radiative properties of strongly coupled, highly correlated, and frequently weakly emissive plasma systems formed in matter irradiated by sub-petawatt and petawatt class lasers. After reviewing the properties of different X-ray crystal spectrometers, high-resolution X-ray diagnostic methods are surveyed with respect to their potential to study plasma-induced and externally induced radiation fields, suprathermal electrons, and strong electromagnetic field effects. Atomic physics in dense plasmas is reviewed with emphasis on non-Maxwellian non-LTE atomic kinetics, quasi-stationary and highly-transient conditions, hollow ion X-ray emission, and field-perturbed atoms and ions. Finally, we discuss the role of X-ray free electron lasers with respect to supplementary investigations of matter under extreme conditions via the use of controlled high-intensity radiation fields.

Investigation of light absorption, energy transfer, and plasma dynamic processes in laser-irradiated targets of low average density

The interaction of powerful laser and X-ray pulses with planar low average density (0.5–10 mg/cm3) porous agar-agar targets was experimentally studied. At a laser power density of ∼5 × 1013 W/cm2 (λ = 1.054 μm) the laser light absorption and following energy transfer processes, as well as dynamics of produced plasma were investigated in detail with a variety of optical and X-ray diagnostic methods. Volume absorption is shown to occur in experiments with laser-irradiated agar targets. An extended laser energy deposition region filled with hot (0.8–1 keV) plasma is formed inside a porous target. The laser light absorption efficiency is as high as ∼80%. The emission of 2ω0 and 3ω0/2 harmonics from laser-produced plasma is observed over the time of the laser pulse even with agar targets of 0.5 mg/cm3 average density. Characteristics of energy transfer in low-density porous media are measured in experiments on illumination of agar targets by laser pulses or X rays emitted by a thin Cu converter. The hydrodynamic mechanism is responsible for the energy transfer in laser-illuminated porous targets and the radiative energy transfer seems to be dominant in the case of X-ray irradiation. The experimental data are in reasonable agreement with predictions of a developed theoretical model describing the hot plasma layer formation and the two-stage homogenization process within the illuminated porous targets.

Interaction of a high-power laser beam with low-density porous media

We have experimentally investigated the processes of laser light absorption and energy transfer in porous targets made of “agar-agar” (C14H18O7) with an average density of 1–4 mg/cm3 illuminated by the focused beam of a neodymium laser with an intensity of 1014 W/cm2 within a pulse of duration 2.5 ns. Many important scientific and technical problems, e.g., inertial-confinement thermonuclear fusion, the creation of lasers in the x-ray regime, and the modeling of astrophysical phenomena under laboratory conditions, can be successfully addressed by using low-density porous media as components of such targets. In our experiments with porous targets of variable density and thickness we used optical and x-ray diagnostic methods, which ensured that our measurements were made with high temporal and spatial resolution. We show that a region forms within the porous target consisting of a dense high-temperature plasma which effectively absorbs the laser radiation. Energy is transferred from the absorption region to the surrounding layer of porous material at up to 2×107 cm/s. Experimental data are in good agreement with the predictions of our theoretical model, which takes into account the specific features of absorption of laser radiation in a porous material and is based on representing the energy transfer within the material as a hydrothermal wave.