Simultaneous 3D Visualization of the Microvascular and Neural Network in Mouse Spinal Cord Using Synchrotron Radiation Micro-Computed Tomography / 神经科学通报·英文版

Effective methods for visualizing neurovascular morphology are essential for understanding the normal spinal cord and the morphological alterations associated with diseases. However, ideal techniques for simultaneously imaging neurovascular structure in a broad region of a specimen are still lacking. In this study, we combined Golgi staining with angiography and synchrotron radiation micro-computed tomography (SRμCT) to visualize the 3D neurovascular network in the mouse spinal cord. Using our method, the 3D neurons, nerve fibers, and vasculature in a broad region could be visualized in the same image at cellular resolution without destructive sectioning. Besides, we found that the 3D morphology of neurons, nerve fiber tracts, and vasculature visualized by SRμCT were highly consistent with that visualized using the histological method. Moreover, the 3D neurovascular structure could be quantitatively evaluated by the combined methodology. The method shown here will be useful in fundamental neuroscience studies.

3D Histology Using the Synchrotron Radiation Propagation Phase Contrast Cryo-microCT / 체질인류학회지

3D histology is a imaging system for the 3D structural information of cells or tissues. The synchrotron radiation propagation phase contrast micro-CT has been used in 3D imaging methods. However, the simple phase contrast micro-CT did not give sufficient micro-structural information when the specimen contains soft elements, as is the case with many biomedical tissue samples. The purpose of this study is to develop a new technique to enhance the phase contrast effect for soft tissue imaging. Experiments were performed at the imaging beam lines of Pohang Accelerator Laboratory (PAL). The biomedical tissue samples under frozen state was mounted on a computer-controlled precision stage and rotated in 0.18° increments through 180°. An X-ray shadow of a specimen was converted into a visual image on the surface of a CdWO4 scintillator that was magnified using a microscopic objective lens (X5 or X20) before being captured with a digital CCD camera. 3-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed were performed using Amira software. In this study, We found that synchrotron phase contrast imaging of frozen tissue samples has higher contrast power for soft tissue than that of non-frozen samples. In conclusion, synchrotron radiation propagation phase contrast cryo-microCT imaging offers a promising tool for non-destructive high resolution 3D histology.

In vitro effect of amorphous calcium phosphate paste applied for extended periods of time on enamel remineralization

Abstract Dental applications based on the unique characteristics of amorphous calcium phosphate stabilized by casein phosphopeptides (CPP-ACP) have been proposed, as well as the improvement of its properties. Objectives: The objective of this study was to determine the ability of topically applied CPP-ACP from a commercial product to remineralize subsurface lesions when applied for extended periods of time (3 h and 8 h). Material and Methods: Artificially induced carious lesions were produced in 50 bovine enamel blocks previously selected by surface hardness. After treatments with gel without F and CPP-ACP applied for 1 minute (Placebo); 2% NaF neutral gel applied for 1 minute (Fluoride 1 min); CPP-ACP applied for 3 min (ACP 3 min); and CPP-ACP applied for 3 h (ACP 3 h) and for 8 h (ACP 8 h), the enamel blocks were submitted to the remineralization pH-cycling. Surface hardness and synchrotron micro-tomography were used to determine the percentage of surface hardness recovery (%SHR) and to calculate mineral concentration (gHAp.cm−3), respectively. The data were submitted to ANOVA followed by the Student-Newman-Keuls test (p<0.05). Results: Fluoride gel presented higher %SHR followed by ACP 3 min (p<0.001). No difference (p = 0.148) was found for Placebo, ACP 3 h and ACP 8 h groups for %SHR. Fluoride gel showed greater mineral concentration (p<0.001) when compared with the other groups. ACP 3 min demonstrated a significant difference (p<0.001) from ACP 3 h and ACP 8 h. The ACP 3 h and 8 h presented a subsurface lesion with development of laminations in all blocks. Conclusion: In this in vitro study the use of CPP-ACP for extended periods of time did not produce an additive effect in the remineralization process.

The effect of nerve preservation methods on rat sciatic nerve structures studied with Synchrotron small-angle X-ray scattering (SAXS)

BACKGROUND: Synchrotron small-angle X-ray scattering (SAXS) is a very useful technique for experimental study of the nano-structure of the nervous system of animals. The study was designed to evaluate nerve preservation methods for the measurement of SAXS patterns. METHODS: Normal sciatic nerves extracted from male Sprague- Dawley rats were preserved in saline (N = 2), formalin (N = 2) or liquid nitrogen (N = 2) for 1 day, followed by measurement of SAXS patterns. SAXS patterns of normal sciatic nerves (N = 3) extracted just before the initiation of the experiment were used as controls. The study was carried out using the 4C1 beamline at Pohang Accelerator Laboratory in Korea. Incoming X-rays were monochromatized at 11 keV using a double multilayer (WB4C) monochromator with beam size of approximately 0.5 (V) × 0.8 (H) mm2. The exposure time was set at 60 sec, and 8 to 12 images per sample were acquired at a 0.5 mm interval. RESULTS: The periodic peaks of interfibrillar space between collagen fibrils were undetectable. The periodic peaks of the myelin sheath and collagen fibers were weakly detected or undetected in the nerves preserved in normal saline or formalin. The periodic peaks and intensity of the myelin sheath, collagen fibers, and interfibrillar space between collagens in the nerves preserved in liquid nitrogen were comparable to those of nerves in the ex vivo state. CONCLUSIONS: The study results indicated that preservation of nerves in liquid nitrogen is adequate for measurements with SAXS. However, saline and formalin preservation techniques were inadequate for SAXS measurement.

Evaluation methods of angiogenesis in experimental liver fibrosis / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the methods for assessing angiogenesis in experimental liver fibrosis.</p><p><b>METHODS</b>Male C57BL/6 mice were randomly divided into a normal (unmodeled) group and a liver fibrosis model group.The model was established by a 4-week course of 10% CCl4 solution (in olive oil) intraperitoneal injection. Liver vasculature was observed by magnetic resonance (MR),computed tomography (CT),synchrotron radiation X-ray,and von Willibrand factor(vWF) immunofluorescence staining. Liver inflammation and fibrosis were observed by staining with hematoxylin-eosin and Sirius red.The t-test and Pearson's correlation analysis were used for statistical analyses.</p><p><b>RESULTS</b>Compared with the normal group,the model group had more robust inflammation and fibrosis in liver tissue.The liver tissue in the modeled mice showed significant deceases in MR signal intensity on T2WI before and after enhancement (386.67+/-69.04 vs.492.67+/-112.50,t =-2.456, P=0.026).The liver tissue in the modeled mice also showed significantly decreased enhancement CT values (P < 0.01).Synchrotron radiation X-ray imaging showed that the small vessels in the liver tissues of the modeled mice were significantly increased compared to that in the normal mice (P < 0.01).The MR T2W enhanced signal value (439.67+/-104.80, Pearson's r=0.714, P=0.009) and microvascular relative length (676.53+/-122.75, Pearson's r=0.791, P=0.002) were positive correlated with microvessel density (MVD) (14.50+/-5.95),as shown by detection of labeled vWF.The before and after CT enhancement difference (132.60+/-57.02, Pearson's r=-0.612, P=0.034) was negatively correlated with MVD.</p><p><b>CONCLUSION</b>s MR,CT and synchrotron radiation X-ray imaging can be used for assessing angiogenesis in liver fibrosis,and the findings from each are correlated with the traditional MVD detection method. The two-dimensional imaging of synchrotron radiation X-ray is more intuitive,and has been confirmed as an effective evaluation method for liver angiogenesis.</p>

Structural analysis of a ligatured rat sciatic nerve in the ex vivo state using synchrotron small-angle X-ray scattering (SAXS)

BACKGROUND: To understand the fundamentals of neural tissue injury, experiments on the nano-structured nerve system of animals are essential. This study was designed to reveal the nanostructure changes of an isolated ligatured rat sciatic nerve using the synchrotron small-angle X-ray scattering (SAXS) technique. METHODS: Male Sprague-Dawley rats (weighing approximately 250 grams) were used in this study. The SAXS patterns of 1 week after ligatured nerves (N = 5) and the normal sciatic nerves (N = 5) for the control were acquired after extracted approximately 15 mm before the experiment. Experiments were conducted at the 4C1 beam line at the Pohang Accelerator Laboratory in Korea. The exposure time was 60 sec, and 8 to 12 images per sample were acquired in 0.5 mm intervals, including the regions above, around and below the ligatured position. RESULTS: The periodic peaks of the myelin sheath and the interfibrillar space of collagen completely disappeared at the ligatured position. Farther from the ligatured point, weak and quite different SAXS patterns were observed for the myelin sheath and interfibrillar space. However, the collagen fiber peaks appeared at all positions, although they were weaker near the ligatured position. CONCLUSIONS: The ligature treatment totally destroyed the myelin sheath and interfibrillar space of collagen. In addition, retrograde degeneration developed 2 mm above the ligatured site. The myelin sheath and interfibrillar space of collagen were damaged 6 mm below the ligatured site. However, the collagen fiber structure was not significantly affected by the ligature, indicating a much different structural organization.

Quantitative structure characteristics and fractal dimension of Chinese medicine granules measured by synchrotron radiation X-ray computed micro tomography / 药学学报

The shape and structure of granules are controlled by the granulation process, which is one of the main factors to determine the nature of the solid dosage forms. In this article, three kinds of granules of a traditional Chinese medicine for improving appetite and promoting digestion, namely, Jianwei Granules, were prepared using granulation technologies as pendular granulation, high speed stirring granulation, and fluidized bed granulation and the powder properties of them were investigated. Meanwhile, synchrotron radiation X-ray computed micro tomography (SR-µCT) was applied to quantitatively determine the irregular internal structures of the granules. The three-dimensional (3D) structure models were obtained by 3D reconstruction, which were more accurately to characterize the three-dimensional structures of the particles through the quantitative data. The models were also used to quantitatively compare the structural differences of granules prepared by different granulation processes with the same formula, so as to characterize how the production process plays a role in the pharmaceutical behaviors of the granules. To focus on the irregularity of the particle structure, the box counting method was used to calculate the fractal dimensions of the granules. The results showed that the fractal dimension is more sensitive to reflect the minor differences in the structure features than the conventional parameters, and capable to specifically distinct granules in structure. It is proved that the fractal dimension could quantitatively characterize the structural information of irregular granules. It is the first time suggested by our research that the fractal dimension difference (Df,c) between two fractal dimension parameters, namely, the volume matrix fractal dimension and the surface matrix fractal dimension, is a new index to characterize granules with irregular structures and evaluate the effects of production processes on the structures of granules as a new indicator for the granulating process control and optimization.

Analysis of ultrastructural changes in the rat sciatic nerve after exposure to pulsed radiofrequency using small angle X-ray scattering (SAXS)

BACKGROUND: Pulsed radiofrequency (PRF) may be used in the treatment of patients with some pain syndromes that cannot be controlled by alternative techniques. The objective of the present study is to examine the ultrastructural changes in rat sciatic nerve after PRF, using synchrotron small angle X-ray scattering (SAXS). METHODS: Twenty rats (Male Sprague-Dawley, about 250 grams) were used this study. The PRF is applied to the afferent axons of the sciatic nerves of the rats in ex vivo state, and the ultrastructure of axons were studied after 1 (N = 5), 4 (N = 5), and 6 (N = 5) weeks by SAXS. The control (N = 5) consisted of non-treated sciatic nerve to provide a statistical differential comparison. RESULTS: In the PRF group, the periodic peaks of myelin sheath and collagen fibrils were not changed compared to the control group, in the time progression of 1, 4, and 6 weeks. But the periodic peaks of interfibrillar distance of collagen were greater at 1 and 4 weeks after PRF, comparing to the control group, but it had tendency to return to normal in 6 weeks. CONCLUSIONS: It is suggested that PRF did not induce ultrastructural change of myelin sheath and collagen fiber, but it induced the change of distance between collagen fibrils of the nerve tissue. This change was not caused by thermal injury but by electromagnetic fields and it is reversible.

Peripheral nerve injury caused by needle impalement: Synchrotron small-angle X-ray scattering study in ex-vivo rat sciatic nerve

BACKGROUND: Direct puncture by a needle is a risk factor for nerve damage. This study was designed to demonstrate nerve damage caused by a needle using the synchrotron small-angle X-ray scattering (SAXS) technique. METHODS: A 15 mm section of rat (Male Spargue-Dawley, about 250 grams) sciatic nerves were involved in this study. The nerve specimen for the experiment (N = 5) was punctured 5 times by a needle (25 G, 100 beveled) under general anesthesia with enflurane. The needle was placed perpendicular to the nerve and the needle bevel was placed parallel to the nerve. The SAXS patterns of the punctured nerves, extracted about 15 min prior to the experiment, were acquired after 1 week. The SAXS patterns of a normal sciatic nerve (N = 5), extracted about 15 min prior to the experiment, were measured in order to provide a comparison. Experiments were carried out at 4C1 beamline at Pohang Accelerator Laboratory in Korea. Incoming X-rays were monochromatized at 11 keV using a double multilayer (WB4C) monochromator; the beam size was around 0.5 (V) x 0.8 (H) mm2. The exposure time was 60 sec, and 8 to 12 images were acquired per sample with a 0.5 mm interval. RESULTS: In the punctured group, the periodic peaks of myelin sheath and collagen fiber were not changed. However, the periodic peaks of interfibrillar distance of collagen were greatly changed. CONCLUSIONS: Direct needle-nerve impalement did not cause damages in myelin sheath and collagen fibers when the needle was placed perpendicular and the needle bevel paralleled to the nerve fiber. This result can imply that the needle slipped into the interfibrillar packing of collagen fibrils.

Identification of the polymorphs of clopidogrel bisulfate based on the steric morphology parameters of crystals / 药学学报

The crystal form of solid substance had intrinsic correlation with its three dimensional crystal morphology. Based on the characterization of the three dimensional crystal morphology of clopidogrel bisulfate, this research is to establish a model based on the three dimensional morphological parameters. The granular samples composed of polymorphs of clopidogrel bisulfate and microcrystalline cellulose (MCC) were scanned by synchrotron radiation X-ray microscopic CT technology (SR-microCT) and the three dimensional structural models for which were constructed. Seven groups of three dimensional morphological parameters were calculated. Finally, the mathematical model was established with the multi-layer perception (MLP) artificial neutral network methods to identify and predict the polymorphs of clopidogrel bisulfate. The success rate of the model prediction for the polymorphs of clopidogrel bisulfate was 92.7% and the area under the ROC curve was 96.2%. The polymorphs of drugs could be identified and predicted through the numerical description of the three dimensional morphology. The volume, number of the vertices and the surface area were the major determinants for the identification of the polymorphs of clopidogrel bisulfate.

Kinetic study on pyrolysis of psoralen / 中国中药杂志

In this study, products of psoralen pyrolysis were detected using a solid pyrolysis apparatus and synchrotron radiation vacuum ultraviolet photoionization mass spectrum (SVUV-PIMS). The pyrolytic kinetics of psoralen was also studied by calculating its initial pyrolytic route in quantum chemistry. According to the findings with SVUV-PIMS, three pyrolytic products were observed, CO, C9H6O and C10H6O2. Theoretically, three fragment pathways were calculated for psoralen, in which the major primary decomposition route was de-CO, and the major secondary decomposition reaction was de-CO reaction of de-CO products.

Exploring the three-dimensional structure of dermal tissues of normal skin and scar in rat with synchrotron radiation X-ray imaging technology / 中华烧伤杂志

<p><b>OBJECTIVE</b>To compare the morphological difference between dermal tissue of normal skin and that of scar in rat, and to explore its structural pattern.</p><p><b>METHODS</b>The full-thickness skin and the scar tissue formed 3 weeks after wound healing from SD rats were harvested as samples, which were prepared appropriately afterwards. Samples were scanned and imaged with synchrotron radiation technology, micro-CT, and phase-contrast imaging technology. The images were rebuilt with three-dimensional software.</p><p><b>RESULTS</b>The micro-CT was materialized by using X-ray generated by synchrotron radiation light source. The structure of dermal tissues was clearly shown with the assistance of phase-contrast imaging technology in the process. It was demonstrated that the dermal tissues of normal skin of rat were mainly composed of collagenous fibers, which twined together to form an olive-like structure. These olive-like structures as basic units were arranged randomly in a certain way. The collagenous fibers in dermal tissue of the scar were arranged in a parallel manner, while some fibers were crooked and arranged in a disorderly manner.</p><p><b>CONCLUSIONS</b>Dermal tissue of normal skin in rat has stable three-dimensional structure, and its basic structure and manner of composition are obviously different from those of scar dermal tissue.</p>

Real time observation of mouse fetal skeleton using a high resolution X-ray synchrotron

The X-ray synchrotron is quite different from conventional radiation sources. This technique may expand the capabilities of conventional radiology and be applied in novel manners for special cases. To evaluate the usefulness of X-ray synchrotron radiation systems for real time observations, mouse fetal skeleton development was monitored with a high resolution X-ray synchrotron. A non-monochromatized X-ray synchrotron (white beam, 5C1 beamline) was employed to observe the skeleton of mice under anesthesia at embryonic day (E)12, E14, E15, and E18. At the same time, conventional radiography and mammography were used to compare with X-ray synchrotron. After synchrotron radiation, each mouse was sacrificed and stained with Alizarin red S and Alcian blue to observe bony structures. Synchrotron radiation enabled us to view the mouse fetal skeleton beginning at gestation. Synchrotron radiation systems facilitate real time observations of the fetal skeleton with greater accuracy and magnification compared to mammography and conventional radiography. Our results show that X-ray synchrotron systems can be used to observe the fine structures of internal organs at high magnification.

Synchrotron Radiation Imaging of Breast Tissue Using a Phase-contrast Hard X-ray Microscope / 의학물리

Synchrotron radiation (SR) imaging enables us to observe internal structures of biologic samples without staining. In this study, we obtained X-ray microscopic images of human breast tissues with 11.1 KeV hard X-ray microscope of the Pohang light source and used zone plates and phase-contrast technique to get high resolution X-ray images. Hard X-ray microscopic images of fibrocystic change and breast cancer tissues with a spatial resolution of 60 nm were obtained and from these images, we could observe the micro-structures of human breast tissue. Also we analyzed and compared these images, which revealed distinct features of each condition. In conclusion, SR imaging with phase-contrast hard X-ray microscope for medical application, especially in breast disease can give some useful information for clinical research.

The human ear anatomical structure imaging based on x-ray phase-contrast / 中国医疗器械杂志

In this paper, the ear anatomic structure imaging is implemented based on X-Ray Phase-Contrast CT. The results of experimentation demonstrate the efficiency of the proposed scheme.

Evaluation of Phase-Contrast Microscopic Imaging with Synchrotron Radiation in the Diagnosis of Breast Cancer and Differentiation of Various Breast Diseases: Preliminary Results / 한국유방암학회지

PURPOSE: A significant improvement of imaging using synchrotron radiation (SR) is obtained by introducing phase-contrast technique. This technique provides greatly enhanced contrast and good soft tissue discrimination with high spatial resolution. The aim of this study was to observe microstructures of pathologic breast specimens including invasive breast cancer using phase-contrast technique with SR and to evaluate the feasibility of phase-contrast imaging in clinical application. METHODS: Phase-contrast microscopic image of normal breast tissue and the images of various breast diseases such as fibrocystic change, ductal carcinoma in situ, invasive ductal carcinoma, Paget's disease were obtained using hard X-ray microscopy with an 11.1 keV monochromatic beam from SR source and CsI (TI) scintillation crystal. Zernike phase-shifter was adapted for phase-contrast hard X-ray microscopy. The visual image was magnified 20 times by microscopic objective lens and captured using a full frame charge-coupled device camera. Obtained images were compared with corresponding histopathologic findings in the optical microscopy. RESULTS: The SR images of various breast diseases were obtained with a good contrast and high visibility by phase-contrast technique. It was possible to observe the microstructures with high spatial resolution down to the micron region. The characteristic features of each disease were consistent with the histopathologic findings of corresponding sample and the images of breast cancer and the other diseases were distinct from each other. CONCLUSION: Using phase-contrast technique, SR images of various breast diseases including breast cancer were obtained. These images were comparable with standard histopathologic findings and showed different features for each disease. The results suggest that phase-contrast microscopic imaging with SR has potential as a diagnostic tool and also its clinical application is feasible, especially in breast imaging.

Synchrotron X-ray Microscopic Imaging of Thyroid Tissues / 대한내분비외과학회지

PURPOSE: X-ray microscopy with synchrotron radiation will soon be a useful tool for innovative x-ray imaging in clinical and laboratory settings. It enables us to observe the detailed internal structure of human tissue samples with great magnification power and excellent resolution. So, it has the possibility to be used for the clinical and research purposes to investigate thyroid diseases if it can effectively evaluate the various conditions of thyroid tissue. To determine the relation with their optical microscopic features, we compared the synchrotron X-ray images of unstained normal and thyroid cancer tissue samples with the histopathologic findings of their adjacent, stained thyroid tissue sections. METHODS: An x-ray microscope was installed on a 1B2 beamline with a Pohang Light Source, which is a 3rd generation synchrotron radiation facility with an operating energy of 2.5 GeV at Pohang, Korea. The x-ray energy was set at 11.1 keV and the x-ray beam was monochromatized using a W/B4C monochromator. Formalin-fixed 10µm-thick female thyroid tissues from normal cases and carcinoma cases were attached on Kapton film for the imaging. The sample was positioned 25 m away from the beam source. The x-ray image of the sample was converted into a visual image on the CsI (TI) scintillation crystal, and it was magnified 20 times by the microscopic objective lens. After an additional 10 times digital magnification, this visual image was captured by a full frame CCD camera. RESULTS: The monochromated x-ray microscopic images of the female thyroid tissues of the normal cases and carcinoma cases were obtained with good resolution. These synchrotron images showed the normal follicular structures in the normal thyroid tissue sections and the characteristic severe stromal fibrosis with collagen fiber accumulation in the cancer tissue sections. CONCLUSION: Owing to the great magnification and excellent resolution, the synchrotron x-ray microscopic images of the normal and cancerous thyroid tissues showed good correspondence with the histopathologic findings of their adjacent, stained tissue sections. So, the x-ray microscopic imaging of thyoid tissue using synchrotron radiation has good potential for use in various clinical and research settings in the future.

Synchrotron Radiation Imaging of Female Breast Tissues Using Phase Contrast Technique / 한국유방암학회지

PURPOSE: X-ray microscopy with synchrotron radiation might be a useful tool for novel x-ray imaging in the clinical and laboratory settings. This technique provides detailed images of internal structures non-invasively. It also has the potential to resolve some of the limitations of conventional breast imaging. We evaluated high resolution synchrotron imaging of breast tissues from normal breasts and breasts with fibroadenomas and cancer. METHODS: A new x-ray microscope was installed on the 1B2 beamline of a Pohang Light Source, at a third generation synchrotron radiation facility in Pohang, Korea. The phase contrast x-ray energy was set at 6.95 keV and the x-ray beam was monochromatized by a W/B4C monochromator. Formalinfixed or unfixed female breast tissue from normal breast as well as breasts with fibroadenomas and carcinoma were attached onto the Kapton film. The sample was positioned 25 m away from the beam source. The x-ray image of the sample was converted into a visual image on the CsI (TI) scintillation crystal, and magnified 20 times by the microscopic objective lens. After an additional 10 fold digital magnification, this visual image was captured by a full frame CCD camera. RESULTS: The monochromated x-ray microscopic images of female breast tissue from normal breast, fibroadenoma and carcinoma cases were evaluated. The total magnifying power of the microscope was x200. This synchrotron radiation imaging enabled us to observe detailed structures of breast tissue without sample preparation such as staining or fixation. CONCLUSION: Using monochromated synchrotron radiation, the x-ray microscopic images of the normal breast and breasts with fibroadenomas and cancer were obtained. From the images obtained, the x-ray microscopic imaging of breast tissue with synchrotron radiation appears to have great potential for clinical and research purposes such as oncology studies, early detection of cancer and as an aid to the pathological diagnosis in the future.

Synchrotron Microangiography of the Rat Heart Using the Langendorff Model

BACKGROUND AND OBJECTIVES: The ability to study microvessels of a beating heart in real time at the level of the capillary is essential for research. However, there are no proven methods currently available to achieve this. The conventional absorption-contrast agents have limitations for studying capillaries. Microangiography with using synchrotron phase-contrast X-ray technology and no contrast agent has recently been reported on. We tried to verify this previous report, and we wanted to visualize the microvessels of a rat heart using air as a contrast agent. MATERIALS AND METHODS: We made the Langendorff apparatus in a hutch of the Pohang Accelerator Laboratory. The images were obtained with a white beam and a monochromatic beam. The visual images were magnified using 3x and 20x optical microscope lenses, and the images were captured with a charge-coupled device camera. RESULTS: We could not duplicate the previously reported findings in which microvessels were visualized without the use of contrast agent. But with using air as a contrast agent, the microvasculature of rat hearts was clearly identified at a spatial resolution of 1.2 microm. Air being absorbed inside a capillary was also observed. Vessels under 10 microm diameter were unable to be visualized with using iodine as a contrast agent. CONCLUSION: Phase contrast imaging already allows spatial resolution of 1 microm, which is enough to inspect capillaries. We were able to obtain images of cardiac capillaries with using air as a contrast agent. Yet air has the fatal limitations in that it causes embolism and ischemia. A more suitable contrast agent or imaging method needs to be developed in order to study the microvessels of a beating heart.

Quasi monochromatic synchrotron radiation source based on compact X-band linear accelerator and terra watt laser for medical diagnostics

X-ray has many useful applications in different research field such as solid state physics, biology, microscopy, medical imaging and diagnostics. One of the great interests in medical application is the Coronary Arterio Graphy [CAG] in which the coronary artery is visualized by contrast agent [iodine] injected into the artery by a catheter that inserted into the artery. This technique is very invasive for patient and associated with high irradiation dose for the patient and for the medical doctor too due to the wide energy spectrum emitted from the X-ray tube used in this technique. In this paper we avoided all the shortcomings of the aforementioned technique by introducing a new, cheap and compact system to produce hard X-ray based on electron-laser collision which enables the physicians to visualize the coronary artery dynamically. The dynamic visualization was possible in this technique due to the high flux of the X-ray photons, which is about 10[11] photons/second. This technique utilizes the advantage of the K-edge attenuation of the iodine [Z = 53] at X-ray energy of 33.169 KeV; hence a monochromatic X-ray radiation just above this energy will give high contrast ratio and clear image. The contrast agent [iodine] in this technique will be injected intravenously instead of using a catheter that inserted into the artery. For that reason the new technique is known as an Intra Venous Coronary Arterio Graphy [IVCAG]. The X-ray flux generated from laser-electron collision has been optimized using CAIN code, while the accelerating cavities of the X-band linear accelerator were designed and optimized using SUPERFISH code. Several scenarios have been proposed to achieve our final goal of compact and stable hard x-ray sources. The progress of the system is presented too