Patricia S. Kaiker

Head impact response - skull deformation and angular accelerations

The response of the head to impact was investigated using live anesthetized and post-mortem Rhesus monkeys and repressurized cadavers. The stationary test subject was struck by a guided moving impactor. The impactor striking surface was fitted with padding to vary the contact force-time characteristics. The experimental technique used a nine-accelerometer system rigidly mounted on the head to measure head motion, transducers placed at specific points below the skull to record epidural pressure, repressurization of both the vascular and cerebral spinal systems of the cadaver model, and high-speed cineradiography of selected test subjects. The results of the tests demonstrate the potential importance of skull deformation and angular acceleration on the injury produced in the live Rhesus and the damage produced in both the post-mortem Rhesus and the cadaver as a result of impact. Language: en

Use of quadruped models in thoraco-abdominal biomechanics research

Pigs and dogs have become common models of human thoraco-abdominal impact response. This paper summarizes a comparative analysis of the dog and pig to the live human accomplished through a series of necropsies performed on pigs and dogs. The results are summarized below. Emphasis is placed on specific aspects which are felt to be important for impact biomechanics. In particular, emphasis is placed upon the effect of tethering structures because of their potential in explaining mechanisms of injury for specific types of trauma such as aortic and certain liver injuries. Some aspects of tethering in the pig and dog are significantly different from that of the live human so care should be taken when using these animals in thoraco-abdominal biomechanics experiments.

Photogrammetric Techniques Using High Speed Cineradiography

A high speed 16 mm cineradiographic system originally developed at the University of Michigan Transportation Research Institute (UMTRI) for use in biomechanics research has been undergoing continuous upgrading in capability. In addition to changes in the structural aspect of the cineradiography, improvements have been made in the procedures used to obtain better image quality, as well as in the methods for interpretation of the digitized results. The current improvements in the system include (1) filtering of the x-ray source before penetration of the subject to increase image contrast and to protect the image tube; (2) hypersensitization of the film to increase its effective speed; (3) development of a neutral density radio-contrast medium for outlining anatomic structure without using the vascular system; and (4) development of procedures for obtaining analytic information about motion of nonrigid anatomic structures from digitized film. This system now consists of cameras that view a 50 mm (2 in.) diameter output of a P-11 phosphor of a high gain, four-stage magnetically focused image intensifier tube, gated on and off synchronously with the motion picture camera shutter. A lens optically couples the input photocathode of the image tube to an x-ray fluorescent (rare earth) screen image produced by a smoothed dc x-ray generator of a conventional type. The system is capable of looking at a large variety of anatomic structures under a wide range of dynamic loading conditions.

Photogrammetric Techniques Using High-Speed Cineradiography

A high-speed 16-mm cineradiographic system previously developed at the University of Michigan Transportation Research Institute for use in biomechanics research has been undergoing a continuous upgrading in capability. In addition to changes in the structural aspect of the cineradiography, improvements have been made in the procedures used to obtain better image quality as well as methods for interpretation of the digitized results. The current improvements in the system include: 1) filtering the X-ray source before penetration of the subject to increase image contrast as well as to protect the image tube; 2) pre-processing of the film to increase its effective speed; 3) development of a neutral density radio-contrast media for outlining anatomical structure without using the vascular system; and 4) development of procedures for obtaining analytical information about motion of non-rigid anatomical structures from digitized film. This system now consists of either a 35-mm Photosonics 4B, a 16-mm Photosonics 1B, or a 16-mm Milliken which views a 50-mm (2-inch) diameter output of a P-11 phosphor of a high gain, four-stage magnetically focused image intensifier tube, gated on and off synchronously with the motion picture camera shutter. A lens optically couples the input photocathode of the image tube to an X-ray fluorescent (rare earth) screen image produced by a smoothed DC X-ray generator of a conventional type. The system is capable of looking at a large spectrum of anatomical structures under a wide range of dynamic loading conditions.