ABSTRACT
We design and analyse a flexible non-contact electromagnetic sensor for monitoring breathing. This paper presents the sensor design and the theoretical model for the expected sensitivity from which we optimize design components. The primary application of this device is in non-invasive sleep monitoring and it has the potential to be useful for detection of both adult and infant apnea. The conductivity changes of the lungs during breathing are monitored by inducing eddy currents within them. The sensor consists of a small coil that acts as both a transmitter and a receiver. The theoretical sensitivity of the sensor to breathing changes is calculated and corresponds within the assumptions of the model to the measured results.
Subject(s)
Electromagnetic Phenomena , Respiratory Function Tests/instrumentation , Respiratory Mechanics/physiology , Telemetry/instrumentation , Transducers , Equipment Design , Equipment Failure Analysis , Reproducibility of Results , Respiratory Function Tests/methods , Sensitivity and SpecificityABSTRACT
Calibrated C-arm fluoroscopy is used for a variety of medical procedures where objects and anatomical structures need to be located in space. Calibration is often based on imaging a grid of fiducial markers and using the C-arm image's geometrical measurements (radius and center) together with the positions of the markers. An on-line technique is developed to automatically locate the fiducial markers and validated on 97 images. The success rate of the detection algorithm is 96.28% with an average error of 0.46 mm and a standard deviation of 0.32 mm.
Subject(s)
Fluoroscopy/instrumentation , Fluoroscopy/methods , Radiographic Image Interpretation, Computer-Assisted/methods , Algorithms , Automation , Brachytherapy , Calibration , Computers , Humans , Models, Theoretical , Radiographic Image Enhancement/methods , Radiotherapy Planning, Computer-Assisted/methods , Radiotherapy, Computer-Assisted/methods , SoftwareABSTRACT
Materials for solid photoacoustic breast phantoms, based on poly(vinyl alcohol) hydrogels, are presented. Phantoms intended for use in photoacoustics must possess both optical and acoustic properties of tissue. To realize the optical properties of tissue, one approach was to optimize the number of freezing and thawing cycles of aqueous poly(vinyl alcohol) solutions, a procedure which increases the turbidity of the gel while rigidifying it. The second approach concentrated on forming a clear matrix of the rigid poly(vinyl alcohol) gel without any scattering, so that appropriate amounts of optical scatterers could be added at the time of formation, to tune the optical properties as per requirement. The relevant optical and acoustic properties of such samples were measured to be close to the average properties of human breast tissue. Tumour simulating gel samples of suitable absorption coefficient were created by adding appropriate quantities of dye at the time of formation; the samples were then cut into spheres. A breast phantom embedded with such 'tumours' was developed for studying the applicability of photoacoustics in mammography.
