X-ray Television System Research Articles

Local cone beam CT: how did it all start?

The mathematical theory of CT was proposed by J. Radon in 1917. It was declared that the projection of whole data sets was needed to reconstruct CT images. Therefore, according to J. Radon's original theory, local cone beam CT (local CBCT) was impossible to achieve.In this paper, I discuss how local CBCT was discovered and developed. Its development required many technical elements, such as a turntable and X-ray television system, for basic experiments such as those on which narrow collimation theory and multifunctional panoramic tomography were based. These experiments endured many failures during development.Now, local CBCT is extremely popular in dental practice because local CBCT has a low radiation dose and high resolution. This paper introduces the technical elements and outlines the important stages during the development of local CBCT in the 1990s.

Simulation of X-Ray Television System Output Signal Based on CMOS-Matrixes

Various X-ray television systems are used for radiation control of materials and products, both indirect conversion of radiation images and direct conversion systems. X-ray television system type "X-ray screen - optics - CMOS-matrix" have a number of advantages over others: the ability to change the X-ray scintillation screen, which allows you to change the size of the working field and other system parameters; short image acquisition time; simplicity of construction; small dimensions and weight; low cost. The development of digital X-ray television systems requires the solution of important scientific and technical problems, which include: increasing the signal-to-noise ratio and, accordingly, the sensitivity of control, increasing the quantum efficiency of image converters, optimizing operating modes to ensure high quality radiation images.The aim of this research was to develop a model of X-ray television system. A physical and topological model of X-ray image transformation in X-ray television systems of the “X-ray screen — optics — CMOS-matrix” type has been developed during research. The math model allows to calculate the characteristics of X-rays at the output of the X-ray tube and the object under study, the intensity of the screen, the light intensity on the surface of the CMOS matrix after passing the optics, calculate the charge packet in a pixel and the output signal systems. The block diagram of the X-ray television system includes the following components: X-ray machine, object, scintillator (screen), mirror and lens with CMOS-matrix. The first stage of creating a through mathematical model is to simulate X-rays at a certain distance from the anode of the X-ray tube. The second stage of creating an end-to-end mathematical model of X-ray television system based on CMOS matrices of the optical range is the modeling of the process of converting X-rays, which corresponds to the shadow X-ray image of the object, into visible range radiation.The developed physical and topological model of X-ray image transformation in X-ray television systems of the type "X-ray screen - optics - CMOS-matrix" allows us to calculate the characteristics of X-ray television system at the design stage, which will save time and money on system development and also select the optimal modes of operation for the study of certain materials. The found results are a perspective direction in development of technology of research of materials that will allow to reduce cost of installations for researches.

Improvement of parameters X-ray television systems on the basis of electronic converters

Flat Panel Detectors (FPD) emerge as a next-generation digital x-ray technology. The numerous advantages of flat panel detectors over x-ray film, computed radiography image plates, and image-intensifier tubes are given. They include time efficiency through bypassing chemical processing and the ability to digitally transfer and enhance images. The most important parameters of different technologies are discussed. The comparison table of modern FPD is presented.Emergence and distribution of industrial television, creation of different types of vacuum transfer tubes, in particular for x-ray range, and then and their solid-state analogs promoted use and development the x-ray TV systems of methods of researches. In comparison with radiographic these methods have essential advantages and open essentially new opportunities of researches. With creation and mass introduction of modern computer facilities, in particular her attraction to processes of registration, visualization and processing of shadow x-ray images of objects. Now the special branch is put by x-ray TV systems of pulse action that are widely used in medicine, defectoscopy, military science and different technological processes. Thanks to a number of essential positive qualities (the small weight and dimensions, simplicity of a design, an opportunity of both the panoramic, and directed raying, the low power consumption and also an opportunity to control dynamic objects and processes) devices have received the greatest use in technology of nondestructive control of materials in non-stationary conditions.The device and the scheme of operation of the x-ray electron-optical converter with an axial arrangement of the receiver is considered. As the converter light signal matrixes on the basis of charge-coupled devices, and also CMOS sensors are used. Transformation of x-ray radiation to the image, available to the operator, takes place several stages. At each step of transformations primary information is distorted that leads to deterioration in the visual image. Key parameters of x-ray electron-optical converter are specified, shortcomings of this type of technologies are noted.By means of digital the x-ray TV systems of systems it is possible to receive images which quality is much higher qualities of x-ray films and computer radiography. As a result of the big relation signal/noise for digital detector system possible indication of defects, is less than the size of pixel. The sizes of solid-state detectors several times smaller for x-ray electron-optical converter. Besides they have no geometrical distortions and reflections. Other advantage of flat detectors is much faster processing of results at rather high quality of the image which gives a gain in time. The digital X-ray analysis allows to reduce a dose of x-ray radiation due to installation of an exposition at which the necessary noise level is supported.The development and improvement of technologies and technical means in the x-ray non-destructive control has taken the way of using highly stable sources of radiation, modern radiation converters, computer methods of their management, application of the newest methods of digital image processing and their analysis. There is an active transition of control systems with the use of radiation x-ray electron-optical converter to systems using multi-element transducers manufactured by microelectronics: amorphous selenium and amorphous silicon. The use of a television channel in such systems greatly expands the functionality of the equipment.Ref. 36, fig. 4, tabl. 3

Simulation of the formation processes of digital x-ray image

The mathematical model of converting X-ray images in "scintillator – CCD” X-ray television systems was developed. This model allows to calculate the characteristics of X-ray in the output of the X-ray tube and behind the object of research, the glow intensity of X-ray screen, the intensity of light on the surface of the CCD-sensor after passing optics, charge in any pixel of CCD and the output signal from it, the signal-to-noise ratio in the output signal and quantum efficiency of X-ray detector.Reference 10, figures 1, table 1.

Model of the 3D X-ray television system

Flat-panel volume computed tomography (VCT) systems enables imaging of entire organs in one axial acquisition. Higher spatial resolution in such systems can be obtained because of moving patient closer to the digital receptor. It can be used not microfocus X-ray tubes, that is shown at the optical transfer function. Stands for such CT system become simpler. As flat panels reliable, comparatively not expensive CCD sensor array structure with good spatial resolution can be used. 3D image can be formed in radiologist’s mind when revolving object is shown on the monitor’s screen. Enumerated factors make it possible to construct new generation of inexpensive fluoroscopic systems with 3D and CT modes.

Hypoxic pulmonary vasoconstriction disappears in a rabbit model of cavopulmonary shunt

Background Cavopulmonary shunt is widely known as an interim staging procedure in patients with single-ventricle physiology. However, the physiologic characteristics of the pulmonary arterial system after cavopulmonary shunt are not clearly understood. In this article, we developed a rabbit cavopulmonary shunt model and studied the morphologic changes and physiologic characteristics (namely, hypoxic pulmonary vasoconstriction) of pulmonary arteries after cavopulmonary shunt. Methods Male Japanese white rabbits aged 12 to 16 weeks were used for the study. In 5 rabbits, the superior vena cava was anastomosed to the right pulmonary artery in an end-to-side fashion, followed by a proximal side ligation of the right pulmonary artery (cavopulmonary shunt group). In 4 rabbits, the superior vena cava and the right pulmonary artery were dissected and clamped for 10 minutes without making a cavopulmonary shunt (sham group). Two weeks after the operation, we then measured the internal diameter of the acinar (internal diameter, 164 ± 7 μm), the lobular (305 ± 13 μm), and the segmental (669 ± 16 μm) pulmonary arteries in both controlled and hypoxic conditions by using a specially designed x-ray television system. Also, morphometric measurements were made in the pulmonary arteries around the terminal bronchioles. Results Two weeks after the operation, the arterial oxygen tension under room air conditions was significantly lower in the cavopulmonary shunt group than in the sham group (68.2 ± 2.2 mm Hg vs 91.1 ± 1.9 mm Hg; P = .01). The baseline internal diameters in the acinar and the lobular (resistance), but not the segmental (conduit), pulmonary arteries on the anastomosed side of the cavopulmonary shunt group were significantly larger than those of pulmonary arteries on the nonanastomosed side of the cavopulmonary shunt group and the sham group. Moreover, the pulmonary arteries on the anastomosed side of the cavopulmonary shunt group did not respond to hypoxia, whereas those on the nonanastomosed side of the cavopulmonary shunt and sham groups did have local internal diameter reductions in the acinar and lobular arteries (−1.1% ± 1.0% in the anastomosed side vs −17.7% ± 3.5% in the nonanastomosed side vs −20.9% ± 6.1% in the sham group; P = .03). In the morphometric studies, the internal diameter of the pulmonary artery accompanying the terminal bronchiole in the anastomosed side of the cavopulmonary shunt group was significantly larger, and the ratio of medial thickness relative to the outer diameter was smaller compared with ratios in the nonanastomosed side of the cavopulmonary shunt group and the sham group. Conclusions We developed a rabbit cavopulmonary shunt model. In the anastomosed side of the cavopulmonary shunt group, the peripheral pulmonary arteries, which contributed greatly in regulating the pulmonary vascular resistance, had a local reduction in the basal vascular tone and no hypoxic vasoconstriction 2 weeks after the operation.

The Effect of Reduction Capability of Resin Material on the Solder Wettability for Electrically Conductive Adhesives (ECAs) Assembly

Electrically conductive adhesives (ECAs) have been developed as an alternative to traditional Sn-Pb solders for electronic and optoelectronic applications. However, there are critical limitations such as the low conductivity, and unstable contact resistance. These limitations have seriously hindered the broad applications of ECAs. In order to overcome these limitations, a new formulation using Pb-free conducting filler particles was proposed. Our previous study proved that the metallurgical interconnections among conducting filler particles and between particles and the conducting pads were established by process control. In particular, it was found that the wetting behavior of conducting fillers in ECAs is one of the main mechanisms for the establishment of conduction paths. In this study, we propose the fundamental concept of an assembly process using fusible Pb-free conducting filler particles. Also, the effect of the reduction capability of base resin material on the solder wetting property was investigated. As candidates for ECA compositions, two types of resin materials and two lead-free solders were investigated. The reflow temperature profiles for each ECA formulation were determined using a differential scanning calorimeter (DSC) dynamic scan. The wettabilities of the lead-free solders were investigated using an optical microscope with a CCD camera and a microfocus Xray television system. It was found that the developed resin material with an intrinsic reduction capability shows good wettabilities in both leadfree candidates.

Changes in functional and histological distributions of nitric oxide synthase caused by chronic hypoxia in rat small pulmonary arteries.

1. Chronic hypoxia (CH) increases lung tissue expression of all types of nitric oxide synthase (NOS) in the rat. However, it remains unknown whether CH-induced changes in functional and histological NOS distributions are correlated in rat small pulmonary arteries. 2. We measured the effects of NOS inhibitors on the internal diameters (ID) of muscular (MPA) and elastic (EPA) pulmonary arteries (100-700 micro m ID) using an X-ray television system on anaesthetized rats. We also conducted NOS immunohistochemical localization on the same vessels. 3. Nonselective NOS inhibitors induced ID reductions in almost all MPA of CH rats (mean reduction, 36+/-3%), as compared to approximately 60% of control rat MPA (mean, 10+/-2%). The inhibitors reduced the ID of almost all EPA with similar mean values (approximately 26%) in both CH and control rats. On the other hand, inducible NOS (iNOS)-selective inhibitors caused ID reductions in approximately 60% of CH rat MPA (mean, 15+/-3%), but did so in only approximately 20% of control rat MPA (mean, 2+/-2%). This inhibition caused only a small reduction (mean, approximately 4%) in both CH and control rat EPA. A neuronal NOS-selective inhibitor had no effect. 4. The percentage of endothelial NOS (eNOS)-positive vessels was approximately 96% in both MPA and EPA from CH rats, whereas it was 51 and 91% in control MPA and EPA, respectively. The percentage for iNOS was approximately 60% in both MPA and EPA from CH rats, but was only approximately 8% in both arteries from control rats. 5. The data indicate that in CH rats, both functional and histological upregulation of eNOS extensively occurs within MPA. iNOS protein increases sporadically among parallel-arranged branches in both MPA and EPA, but its vasodilatory effect is predominantly observed in MPA. Such NOS upregulation may serve to attenuate hypoxic vasoconstriction, which occurs primarily in MPA and inhibit the progress of pulmonary hypertension.

K ATP channels predominantly regulate conduit vessel tone in normoxic cat pulmonary arteries in vivo

Through our investigations of the intact pulmonary circulation, we aimed to find out whether K ATP channels contribute to regulating basal vascular tone and to clarify which vascular segments dilate during K ATP channel activation under basal tone conditions. Using an X-ray television system on anesthetized cat lungs, we measured internal diameter (ID) responses to two K ATP channel inhibitors (glibenclamide and 4-morpholinecarboximidine- N-1-adamantyl- N′-cyclohexyl-hydrochloride (U-37883A)) and to an activator (levcromakalim) in normoxic pulmonary arteries. In conduit arteries (800–3000 μm ID), the inhibitors and activator induced larger ID constrictions (14–17%) and dilatations (29–32%), respectively. However, in resistance arteries (<500 μm), the constriction response was negligible and the dilatation response relatively small (5–10%). The data suggest that K ATP channels are active and capable of regulating basal vascular tone primarily within conduit pulmonary arteries even though these channels are present in all pulmonary arteries.

Use of an implanted marker and real-time tracking of the marker for the positioning of prostate and bladder cancers

Purpose: A real-time tracking radiotherapy was investigated to assess its usefulness in precise localization and verification of prostate and bladder cancers. Methods and Materials: The real-time tracking radiation therapy (RTRT) system consists of implantation of a 2.0-mm gold marker into a clinical target volume (CTV), three-dimensional radiation treatment planning (3DRTP) system, and the use of two sets of diagnostic x-ray television systems in the linear accelerator room, image processing units, and an image display unit. The position of the patient can be corrected by adjusting the actual marker position to the planned marker position, which has been transferred from the 3DRTP and superimposed on the fluoroscopic image on the display unit of the RTRT system. The position of the markers can be visualized during irradiation and after treatment delivery to verify the accuracy of the localization. Ten patients with prostate cancer and 5 patients with bladder cancer were examined using this system for the treatment setup on 91 occasions. Results: After manual setup using skin markers, the median of absolute value of discrepancies between the actual position of the marker and the planned position of the marker for prostate cancer was 3.4 (0.1–8.9) mm, 4.1 (0.2–18.1) mm, and 2.3 (0.0–10.6) mm for the lateral, anteroposterior, and craniocaudal directions, respectively. The 3D median distance between the actual and planned positions of the marker was 6.9 (1.1–18.2) mm for prostate cancer and 6.9 (1.7–18.6) mm for bladder cancer. After relocation using RTRT, the 3D distance between the actual and planned position of the marker was 0.9 ± 0.9 mm. Median 3D distances between actual positions after treatment delivery and planned positions were 1.6 (0.0–6.3) mm and 2.0 (0.5–8.0) mm during daily radiotherapy for the marker in patients with prostate cancer and bladder cancer, respectively. Conclusion: We believe the new positioning system can reduce uncertainty due to setup error and internal organ motion, although further improvement is needed for the system to account for the rotational and elastic changes of the affected tissues.

Physical aspects of a real-time tumor-tracking system for gated radiotherapy

Purpose: To reduce uncertainty due to setup error and organ motion during radiotherapy of tumors in or near the lung, by means of real-time tumor tracking and gating of a linear accelerator. Methods and Materials: The real-time tumor-tracking system consists of four sets of diagnostic X-ray television systems (two of which offer an unobstructed view of the patient at any time), an image processor unit, a gating control unit, and an image display unit. The system recognizes the position of a 2.0-mm gold marker in the human body 30 times per second using two X-ray television systems. The marker is inserted in or near the tumor using image guided implantation. The linear accelerator is gated to irradiate the tumor only when the marker is within a given tolerance from its planned coordinates relative to the isocenter. The accuracy of the system and the additional dose due to the diagnostic X-ray were examined in a phantom, and the geometric performance of the system was evaluated in 4 patients. Results: The phantom experiment demonstrated that the geometric accuracy of the tumor-tracking system is better than 1.5 mm for moving targets up to a speed of 40 mm/s. The dose due to the diagnostic X-ray monitoring ranged from 0.01% to 1% of the target dose for a 2.0-Gy irradiation of a chest phantom. In 4 patients with lung cancer, the range of the coordinates of the tumor marker during irradiation was 2.5–5.3 mm, which would have been 9.6–38.4 mm without tracking. Conclusion: We successfully implemented and applied a tumor-tracking and gating system. The system significantly improves the accuracy of irradiation of targets in motion at the expense of an acceptable amount of diagnostic X-ray exposure.

Pulmonary microvascular responses to inhaled prostacyclin, nitric oxide, and their combination in anesthetized cats.

Using an X-ray television system on anesthetized cats, we directly measured internal diameter (ID) changes in identical small pulmonary vessels (100-1,100 microm ID) in response to inhalations of 25, 250, and 2,500 ng/kg/min aerosolized prostacyclin (PGI2), 4 and 34 ppm nitric oxide (NO), and the combination of aerosolized PGI2 and NO. We also compared ID changes during 250 ng/kg/min PGI2 inhalation both with and without an Nomega-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg I.V.) pretreatment. In the arteries, inhaled PGI2 increased 100-900 microm vessel ID in a dose-dependent manner but caused no significant, or only slight, ID increases in the vessels larger than this. The greatest ID increase ( approximately 22%) was in the 100-500 microm arteries in response to 2,500 ng/kg/min PGI2 inhalation. PGI2 also increased the ID of the veins (6-12%), but the results were not dose related. NO inhalation also resulted in non-uniform ID response patterns similar to PGI2 with no significant, or only minimal, ID increases of the arteries >900 microm. The simultaneous inhalation of 2,500 ng/kg/min PGI2 and 34 ppm NO increased the arterial ID (maximum approximately 34%) more than either drug alone and to almost the same extent as brought about by injected papaverine (2 mg/kg), a smooth muscle relaxant. Inhaled PGI2 (250 ng/kg/min) decreased pulmonary arterial pressure and increased arterial ID to nearly the same extent with or without L-NAME pretreatment. These results indicate that inhaled PGI2 and inhaled NO locally dilate 100-900 microm pulmonary arteries in a dose-dependent manner and with a similar ID response pattern, and that the combination of these drugs produces a more enhanced vasodilator effect compared to their separate effects and induces the maximum dilated states. The data also suggest that inhaled PGI2 dilates these arteries directly, rather than via secondary release of endogenous NO.

2255 Three-dimensional (3D) localization and verification of pelvic tumors using internal markers and a double-axial x-ray television system

2255 Three-dimensional (3D) localization and verification of pelvic tumors using internal markers and a double-axial x-ray television system

Vasodilator effects of adrenomedullin on small pulmonary arteries and veins in anaesthetized cats.

1. This study was conducted to determine adrenomedullin (AM) action sites in the pulmonary vascular bed and the relation between its vasodilator effects and vascular tone. Moreover, an examination was made into whether calcitonin gene-related peptide (CGRP) receptors mediate pulmonary vasodilatations induced by AM. To this end, we directly measured internal diameter (i.d.) changes in small pulmonary arteries and veins (100-1100 microns i.d.) by use of an X-ray television system on the in vivo cat lung. 2. Under control (resting vascular tone) conditions, AM injections into the left main pulmonary artery caused dose-related i.d. increases in both small arteries and veins. The mean i.d. increase of the 100-1100 microns arteries (4 +/- 1, 11 +/- 2, and 17 +/- 2% with 0.01, 0.1, and 1 nmol kg-1 AM, respectively) was significantly larger than that for the veins (1 +/- 1, 5 +/- 2, and 7 +/- 2% with 0.01, 0.1 and 1 nmol kg-1 AM, respectively) whatever the injected dose of AM. 3. When unilobar hypoxia (5% O2) had decreased the i.d. of the 100-1100 microns arteries and veins by 16 +/- 3 and 6 +/- 3%, respectively, AM (0.1 nmol kg-1) was able to induce significantly larger i.d. increases in the arteries (28 +/- 3%) and veins (11 +/- 3%) than those under control conditions. 4. The AM-induced i.d. response pattern in the serially connected pulmonary arteries was quite different from that induced by CGRP; AM caused a greater increase in smaller vessels (100-500 microns) than in larger vessels (500-1100 microns). In the case of CGRP, a greater increase was observed in the larger vessels. 5. CGRP8-37 (100 nmol kg-1, i.v., followed by a continuous infusion of 0.2 nmol kg-1 min-1) had no significant effect on the i.d. increase induced by AM (0.1 nmol kg-1) in any serial segments of the arteries and veins. 6. The results indicate that, in the cat, AM induces greater vasodilatation in small pulmonary arteries and lesser vasodilatation in small veins, the maximum dilatation being in the more peripheral arterial segment (100-500 microns). The vasodilator effect of AM was enhanced when vascular tone was elevated. The data suggest that the AM-induced pulmonary vasodilatation is not mediated by CGRP receptors but by its own specific receptor.

Inhaled nitric oxide: diameter response patterns in feline small pulmonary arteries and veins

Using an X-ray television system on the in vivo cat lung, we directly measured internal diameter (ID) changes in the small pulmonary arteries and veins (100-1,100 microns ID) in response to 5, 15, and 40 ppm nitric oxide (NO) inhalations. We also measured to what extent 40 ppm NO inhalation can attenuate large ID constrictions at the different serial segments of the small vessels due to unilobar anoxic (0% O2) exposure. Under normoxic conditions, 5-40 ppm NO inhalations significantly increased the ID of both arteries and veins less than approximately 900 microns dose dependently but caused no significant, or only slight, ID increases in the vessels larger than this, if any at all. The ID increase in the serially connected arteries was nonuniform (4-18, 8-28, and 7-35% with 5, 15, and 40 ppm NO inhalations, respectively), whereas that for the veins was relatively uniform (4-9, 6-17, and 7-18% with 5, 15, and 40 ppm NO, respectively). The maximum ID increase occurred in the 200- to 500- and 200- to 700-microns arteries in response to 5-15 and 40 ppm NO, respectively. Unilobar anoxic exposure significantly decreased the ID of the 100- to 700-microns arteries and veins, but not the ID of the other-sized vessels. The ID decrease in the serially connected arteries was nonuniform (13-29%) but relatively uniform in the veins (8-12%). The maximum ID decrease occurred in the 200- to 300-microns arteries. However, adding 40 ppm NO to the lobe completely eradicated the ID decreases at all segments of the arteries and veins and, instead, caused significant ID increase (11-21%) in the arteries and (10-12%) in the veins. The data indicate that, according to dosage, 5-40 ppm NO inhalations cause selective dilation of approximately 100- to 900-microns pulmonary arteries and veins, particularly the 200- to 700-microns arteries. During anoxic exposure, the vasodilator effect of NO is preserved and can completely reverse the marked pulmonary vasoconstriction.

第24回日本総合健診医学会学術大会講演抄録集 X線テレビの維持・管理

第24回日本総合健診医学会学術大会講演抄録集 X線テレビの維持・管理

Diameter and flow velocity changes of feline small pulmonary vessels in response to sympathetic nerve stimulation.

Using an X-ray television system, we measured directly changes in the internal diameter (ID), flow velocity, and volume flow of the small pulmonary vessels (100-500 microns ID) in response to electrical sympathetic nerve stimulation (SNS) in anaesthetized cats before and after adrenergic receptor blockade. Flow velocity was obtained by measuring the distance that the leading edge of the contrast medium moved per 0.1 s in the small arteries. Volume flow was obtained from the product of flow velocity and cross-sectional area calculated from the ID of the small arteries. SNS was accomplished with 10- to 15-V square-wave pulses of 2-ms duration at 20-30 Hz for 20-s periods. In response to SNS, arterial ID decreased significantly by 8-13% in the 200- to 500-microns vessels but not in the 100- to 200-microns vessels. In the veins, on the other hand, there was no significant ID decrease in any of the 100- to 500-microns vessels. After alpha-receptor blockade (phentolamine, 2 mg/kg i.v.), there were significant ID increases (4-9%) in the 100- to 500-microns arteries in response to SNS, the maximum increases being in the 100- to 200-microns arteries. After beta-blockade (propranolol, 2 mg/kg i.v.), the ID decrease due to SNS in the 200- to 500-microns arteries was enhanced (24-27%) and, in addition, the 100- to 200-microns arteries exhibited a significant ID decrease (18%). Combined alpha- and beta-blockade completely abolished the ID decrease due to SNS. In the veins, on the other hand, no ID change occurred even after alpha- or beta-blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta-Adrenergic mechanisms attenuated hypoxic pulmonary vasoconstriction during systemic hypoxia in cats.

In this study, we examined how locally mediated hypoxic pulmonary vasoconstriction is modulated by autonomic nervous system activation during global alveolar hypoxia (GAH) accompanied by systemic hypoxemia. Using an X-ray television system on the in vivo cat lung, we measured changes in the internal diameter (ID) during GAH and regional alveolar hypoxia (RAH) without systemic hypoxemia in identical small pulmonary arteries and veins (100-600 microns ID). We also analyzed the effects of the autonomic nervous system blockade on the hypoxic ID changes. During GAH the ID of the arteries reduced by 5 +/- 1 and 3 +/- 1% with 10 and 5% O2 inhalations, respectively, whereas during RAH the arterial ID reduced by 12 +/- 1 and 18 +/- 1% with 10 and 5% O2 inhalations, respectively. The magnitude of the ID reduction was significantly smaller during GAH than during RAH. After pretreatment with propranolol, however, GAH induced large ID reductions (16 +/- 1 and 23 +/- 1% with 10 and 5% O2 inhalations) with patterns very similar to those seen during RAH. Phentolamine and atropine had no effect on the response during GAH. The ID reductions during RAH, on the other hand, were unaffected by all the blockers. The results indicate that, in the cat, alveolar hypoxia per se acts locally to constrict the small pulmonary vessels and that the hypoxic vasoconstriction is attenuated by a beta-receptor-mediated vasodilator effect during GAH with systemic hypoxemia. In addition, we found that, after adrenalectomy plus ganglion blockade with hexamethonium bromide, the GAH-induced ID reduction with 5% O2 inhalation was enhanced from 3 to 19%.(ABSTRACT TRUNCATED AT 250 WORDS)

143. ルーチン検査対応 I. I. -DR 透視検査システムの開発(装置・器具 DSA 他)

143. ルーチン検査対応 I. I. -DR 透視検査システムの開発(装置・器具 DSA 他)

Selective and tone-dependent vasodilation of arterial segment in rabbit and feline pulmonary microcirculation in response to ANP.

Using an X-ray television system, we directly measured the changes in internal diameter (ID; 100-600 microns) of small pulmonary arteries and veins in response to intravenous infusion of atrial natriuretic peptide (ANP) in anesthetized rabbits and cats. Under physiological conditions, ANP (0.01-1 micrograms/(kg.min) for 3 min) increased the ID of the small arteries in a dose-dependent manner by 4-9% and by 6-14% in the rabbit and cat, respectively. The maximum increase in ID occurred in the 400-600 microns arteries. In the small veins, however, the peptide had no significant effects on the ID. To simultaneously investigate the ANP-induced responses of pulmonary vessels with different vascular tone in a given lung region, we embolized a part of the rabbit pulmonary vascular tree with micro-beads (80-100 microns diameter) and measured ID responses to ANP (1 microgram/(kg.min) for 3 min) in the embolized vessels with elevated tone and the nonembolized vessels with baseline tone. In the embolized arteries, which had constricted by 31%, ANP induced 27% increase in ID, while in the nonembolized arteries it caused 8% increase in ID. This indicated that in the small arteries, the vasodilator activity of ANP is greatly enhanced under the conditions of elevated vascular tone. In the small veins, however, no significant vasodilation occurred even under the elevated-tone conditions. We concluded that ANP dilates the arterial segments in the rabbit and cat pulmonary microcirculation selectively and in a dose-dependent manner. Furthermore, the pulmonary vasodilator effect of ANP was dependent on the pulmonary vascular tone.