Alan M. Jacobs

Implementing an automatic control system for dynamic radiography

The basic detection system used for dynamic radiography is reviewed. Some practical factors are discussed in the application of dynamic radiography to the mapping of epicardial motion in canines. A fluoroscopic aiming technique is described for hitting specific points on the cardiac silhouette. The development and design of an automatic control system for dynamic radiography is covered. This system accomplishes automatic detector scanning to the proper depth, as well as calibration of the output signal. This output displays the surface position in millimetres. Some results from canine studies are discussed.ZusammenfassungDas für dynamische Radiographie verwendete grundlegende Aufdeckungs-system wird besprochen. Einige praktische Faktoren bei der Anwendung von dynamischer Radiographie auf die Abbildung epikardialer Bewegung bei Hunden werden diskutiert. Es wird ein fluoroskopisches Zielverfahren zum Treffen spezifischer Punkte auf der Herz-Silhoutette beschrieben. Die Entwicklung und Konstruktion eines automatischen Regelsystems für DRG wird eingeschlossen. Dieses System erzielt automatische Detektorabtastung auf die richtige Tiefe, wie auch Kalibrierung des Ausgangssignals. Dieser Ausgang zeigt die Oberflächenlage in mm an. Einige Resultate aus Untersuchungen an Hunden werden besprochen.SommaireLe système de détection de base utilisé en radiographie dynamique est passé en revue. On étudie certains facteurs d’ordre pratique intervenant dans l’application de la radiographie dynamique au tracé du mouvement épicardiaque chez les chiens. On expose une technique de visée fluoroscopique pour atteindre des points particuliers de la silhouette cardiaque. La mise au point et la conception d’un système de réglage automatique en radiographie dynamique sont traitées. Ce système permet une détection par balayage automatique à la profondeur voulue ainsi que l’étalonnage du signal de sortie. Le signal de sortie permet de montrer la position en millimètre de la surface. Certains résultats obtenus par des études sur des chiens sont évalués.

Dynamic Radiography A New Imaging Technique Using Penetrating Radiation

One of the authors (ESK) and his students (Refs. 1-4) have, for several years, investigated system dynamics information contained in the gamma ray field emerging from an operating nuclear reactor core. Early experiments were directed along the lines of obtaining the sys-tem transfer function (frequency response). Either a driven perturbation or the natural noise generated in a neutron chain reaction represented the input to the system. The emerging gamma rays represented the system output. In later experiments, two highly collimated detectors were used to respond to the gamma rays generated in two narrow, intersecting channels through the reactor core. As with the earlier experiments, either a driven perturbation or natural noise phenomena can be used as dynamic system input. Selectivity in gamma ray energy detection and correlation of the two detector outputs yield information regarding the fission rate in the volume of intersection of the two channels under surveilance provided that the input process correlation is of dimensions on the order of (or smaller than) the volume of intersection.

Dynamic Radiography An Evaluation of Cardiac Motion by the Analysis of Scattered Radiation During Fluoroscopy

A non-invasive technique, utilizing scattered radiation, has been developed to monitor and measure the motion of the epicardial surface during fluoroscopy. A number of dogs were studied using a monitoring device which consists of an X-Ray beam collimator, collimated sodium iodide dectetors and their associated electronics. The detector signals are computer processed to obtain frequency fingerprints of epicardial motion that may, in the future, indicate the condition of the myocardium.

Dynamic Radiography: A New Technique For Epicardial Imaging*

A new radiographic system has been developed for use in mapping three-dimensional epicardial motion. The new radiograph consists of an array of detectors arranged such that they monitor 1 cm strip of scattering photons along a contour across the cardiac surface. Synthesis of the detector data permits immediate display of the beating cardiac contour on a CRT screen for observation and analysis. The entire radiographic system is under microprocessor control. Location of the cardiac surface and initial cardiac contour display is possible within ten seconds of a scans initiation. The system has been carefully validated on mechanical models. Studies with anesthetized canines demonstrate the new radiograph in a physiological environment. Eventual clinical use is expected to provide the physician with accurate data on ventricular function at patient costs and radiation dose rates lower than those of other available techniques.

Neutron diffraction intensities from vibrating double-crystal systems

Abstract Thermal neutron diffraction has been studied using single and double quartz crystal systems vibrating in the compressional and flexure modes. A spectral shift has been noted for a vibrating crystal resulting in an increase in most probably diffracted neutron wavelength from 2.2 A to 2.9 A. Double crystal diffraction was found to yield a 95% survival of once diffracted neutrons in the second diffraction, but with a large beam angular divergence. Large amplitude flexure mode studies produced a 30% reduction in diffracted intensity and no measurable effect on beam divergence.

On The Use Of Gamma Ray Images For The Determination Of Human Body Segment Mass Parameters

Studies of the mechanics of motion of the human body have developed to the point where accurate determination of body segment parameters is essential. However, little data has been available on body parameters such as mass, center of mass, and moment of inertia of the major body segments.

Nonintrusive Transaxial Tomography Technique For Velocity Profile Measurement

In industrial diagnostics, direct imaging of dynamic variables is often as important as frame sequences of configuration and composition static distributions. There have been only a few studies presented on the application of transverse axial tomography techniques to the direct development of dynamic images. In this paper, a new nonintrusive transaxial tomography method for the measurement of three-dimensional fluid velocity profiles is suggested. The technique employs the sensing of the transit time of a physical signature which is carried by the fluid. This signature is detected at locations marginal to the fluid flow region and thus usually is represented by a configuration convolution over a region of the flow. Since time of fluid transit is the variable which is imaged, the technique is labelled Transit Time Transaxial Tomography. To aid in development of the idea of the method, it is progressively detailed for the special case of a radioactive nucleus decay signature and a fluid flow meter concept which could be applied to a nuclear power plant. Generalization of the ideas are then presented in the conclusion of the work.

Radiation imaging: an interesting utilization of nuclear engineering methodology

Using well-established nuclear engineering methods, an interesting new radiation imaging technique has been developed. Scattered neutrons and photons have been found to carry detailed information about the dynamics of the internal structure of an opaque object. Employing coded apertures and systems of collimators, scattered radiation fields have been examined to determine the extent and quality of the image information carried on these fields. A medical application of the results of this research has shown that movements of the myocardial surface can be detailed for diagnostic purposes. The success of this research effort substantiates the belief that nuclear engineering educational groups should more fully explore their own potential for growth and contribution in neighboring disciplines. (auth)