Penetration performance of protective materials from crossbow attack: a preliminary study.

Crossbow-related injuries resulting in serious and mortal consequences have increased in recent years, and although significant research exists for both injury and fatality on the human body, limited data exists on the lethality of the bolt and the failure modes of protective materials. This paper concerns itself with the experimental validation of four differing crossbow bolt geometries, their effects on material failure and potentially lethality. During this study, four different types of crossbow bolt geometries were tested against two protection mechanisms that differed in mechanical properties, geometry, mass and size. The results show that at 67 ms-1, ogive, field and combo tips do not provide lethal effect at 10-m range, whilst a broadhead tip will perforate both the para-aramid and a reinforced area of polycarbonate material consisting of two 3-mm plates at 63-66 ms-1. Although perforation was apparent with a more honed tip geometry, the chain mail layering within the para-aramid protection and friction caused by polycarbonate petalling on the arrow body reduced the velocity enough to demonstrate the materials under test are effective at withstanding crossbow attack. Subsequent calculation of the maximum velocity that arrows could achieve if fired from the crossbow within this study shows results close to the overmatch value of each material and therefore a requirement to advance the knowledge in this field to influence the development of more effective armour protection mechanisms.

Fabricación de modelos anatómicos articulares para formación en intervencionismo ecoguiado / Anatomic joint models for eco-guided interventionism training manufacture

Introducción: El intervencionismo ecoguiado ha supuesto un cambio en la forma en que los especialistas de medicina física y rehabilitación se enfrentan al dolor musculoesquelético y a otros problemas como la espasticidad. La implantación de las unidades de intervencionismo ecoguiado mejora los resultados de los tratamientos mínimamente invasivos, habituales en la práctica clínica de nuestra especialidad. El mayor inconveniente de esta práctica es la larga curva de aprendizaje y la dificultad para llevar a cabo prácticas durante los cursos de formación. Objetivo: Desarrollar un sistema de fantomas que permita la práctica de intervencionismo en modelos anatómicos acortando los tiempos de aprendizaje y mejorando la certeza al alcanzar el objetivo de la práctica intervencionista. Métodos: Se describe el método de fabricación de modelos tridimensionales de articulaciones a partir de imágenes obtenidas de tomografía axial computarizada, y su inclusión posterior en moldes realizados con gelatina alimenticia, que permiten obtener unos fantomas similares a modelos articulares reales que posibilitan su estudio mediante técnicas de ecografía y la práctica del intervencionismo ecoguiado. Conclusión: Los modelos articulares tridimensionales con gelatina alimenticia son útiles en la práctica y aprendizaje de las técnicas de intervencionismo ecoguiado articular.(AU)

Introduction: Eco-guided interventionism has changed the way Physical Medicine and Rehabilitation specialists deal with musculoskeletal pain and other problems such as spasticity. The implementation of the Eco-Guided Intervention Units improves the results of the usual minimally invasive treatments in our speciality's clinical practice. The biggest drawback of this practice is the long learning curve and the difficulty of practice during training courses. Objective: To develop a system of phantoms that allow the practice of interventionism in anatomical models by shortening learning times and improving certainty by achieving the objective of interventionist practice. Methods: Describes the method of manufacturing three-dimensional models of joints with images obtained from computerized axial tomography, and their subsequent inclusion in gelatin's made molds, which allow to obtain phantoms, similar to real joint models, that allow to study using ultrasound techniques, and the practice of eco-guided interventionism. Conclusion: Three-dimensional joint models made with gelatin are useful in the practice and learning of joint eco-guided interventionism techniques.(AU)

[Anatomic joint models for eco-guided interventionism training manufacture]. / Fabricación de modelos anatómicos articulares para formación en intervencionismo ecoguiado.

INTRODUCTION: Eco-guided interventionism has changed the way Physical Medicine and Rehabilitation specialists deal with musculoskeletal pain and other problems such as spasticity. The implementation of the Eco-Guided Intervention Units improves the results of the usual minimally invasive treatments in our speciality's clinical practice. The biggest drawback of this practice is the long learning curve and the difficulty of practice during training courses. OBJECTIVE: To develop a system of phantoms that allow the practice of interventionism in anatomical models by shortening learning times and improving certainty by achieving the objective of interventionist practice. METHODS: Describes the method of manufacturing three-dimensional models of joints with images obtained from computerized axial tomography, and their subsequent inclusion in gelatin's made molds, which allow to obtain phantoms, similar to real joint models, that allow to study using ultrasound techniques, and the practice of eco-guided interventionism. CONCLUSION: Three-dimensional joint models made with gelatin are useful in the practice and learning of joint eco-guided interventionism techniques.

Cardiac Tissue-Mimicking Ballistic Gel Phantom for Ultrasound Imaging in Clinical and Research Applications.

Ballistic gel was investigated as a tissue-mimicking material in an anthropomorphic cardiac phantom for ultrasound imaging. The gel was tested for its acoustic properties and its compatibility with conventional plastics molding techniques. Speed of sound and attenuation were evaluated in the range 2-12 MHz. The speed of sound was 1537 ± 39 m/s, close to typical values for cardiac tissue (∼1576 m/s). The attenuation coefficient was 1.07 dB/cm·MHz, within the range of values previously reported for cardiac tissue (0.81-1.81 dB/cm·MHz). A cardiac model based on human anatomy was developed using established image segmentation processes and conventional plastic molding techniques. Key anatomic features were observed, captured and identified in the model using an intracardiac ultrasound imaging system. These favorable results along with the material's durability and processes that allow for repetitive production of detailed whole-heart models at low cost are promising. There are numerous applications for geometrically complex phantoms in research, training, device development and clinical use.

Comparison of Spinal Needle Deflection in a Ballistic Gel Model.

BACKGROUND: Percutaneous diagnostic and therapeutic procedures are commonly used in the treatment of spinal pain. The success of these procedures depends on the accuracy of needle placement, which is influenced by needle size and shape. OBJECTIVES: The purpose of this study is to examine and quantify the deviation of commonly used spinal needles based on needle tip design and gauge, using a ballistic gel tissue simulant. MATERIALS AND METHODS: Six needles commonly used in spinal procedures (Quincke, Short Bevel, Chiba, Tuohy, Hustead, Whitacre) were selected for use in this study. Ballistic gel samples were made in molds of two depths, 40mm and 80 mm. Each needle was mounted in a drill press to ensure an accurate needle trajectory. Distance of deflection was recorded for each needle. RESULTS: In comparing the mean deflection of 22 gauge needles of all types at 80 mm of depth, deflection was greatest among beveled needles [Short Bevel (9.96 ± 0.77 mm), Quincke (8.89 ± 0.17 mm), Chiba (7.71 ± 1.16 mm)], moderate among epidural needles [Tuohy (7.64 ± 0.16 mm) and least among the pencil-point needles [Whitacre (0.73 ± 0.34 mm)]. Increased gauge (25 g) led to a significant increase in deflection among beveled needles. The direction of deflection was away from the bevel with Quincke, Chiba and Short Beveled needles and toward the bevel of the Tuohy and Hustead needles. Deflection of the Whitacre pencil-point needle was minimal. CONCLUSIONS: There is clinical utility in knowing the relative deflection of various needle tips. When a procedure requires a needle to be steered around obstacles, or along non-collinear targets, the predictable and large amount of deflection obtained through use of a beveled spinal needle may prove beneficial.

A contribution to the discussion on the safety of air weapons.

Firearms legislation in the UK stems from the Firearms Act 1968 with its definition of a firearm as a lethal barrelled weapon of any description. The Act allows certain exceptions to be held without licence, most notably air weapons although these are limited by The Firearms (Dangerous Air Weapons) Rules 1969 and related regulations to below 12ft lb (16.3J) for air rifles and below 6ft lb (8.1J) for air pistols. Despite this there are occasional fatalities, typically 1 or 2 each year in the UK, from legally owned air weapons. In the USA there are over 20,000 visits each year to emergency departments due to injuries from air weapons and paintball guns. Despite this, limited research appears to have been carried out into the safety of air weapons and the present study tries to address this. Fresh samples of animal tissue were obtained from an abattoir or butcher and were embedded in ballistic gelatin. Pig heart, lung, liver and shoulder were used. By firing pellets into gelatin alone and into the combination of the gelatin and animal tissue it was possible to compare gelatin as a model for these tissues. The depth of penetration was similar but the residual track appeared to remain more open in the animal tissue. Pellets penetrated completely through the organ, with total penetration of gelatin and organ being typically around 10-15cm. Samples of pig, cow and chicken skin were placed in contact with the gelatin or embedded in the gelatin to simulate the effect of skin on penetration into a body. Chicken skin had no effect, pig skin stopped the pellet and cow skin was perforated by the pellet. If cow skin was embedded in the gelatin there was little effect on the total amount of penetration, but cow skin on the front surface of the gelatin reduced penetration by about 30%. Computed tomography was used to examine the pellet track and to calculate the volume of damage produced. However, due to the similar densities of gelatin and organ a technique had to be developed to differentiate phases. A barium salt paste was applied to outer surfaces and iodine solution or barium nitrate solution containing red food colouring was injected into the pellet track to enhance the contrast of the track. The track through the gelatin tended to enclose itself whereas the track through the organ remained more open, presumably due to the inhomogeneity of the fibrous nature of the tissue. Pellets were also fired at construction materials (wood, plasterboard and brick) and computed tomography used to determine the volume of damage created. Pellets perforated single layers of wood and plasterboard and would embed in a second layer. However, if the two layers were in contact the pellet did not penetrate the first layer. An air rifle pellet could therefore perforate house construction materials, although the resultant kinetic energy would be low and further damage would be limited. Some of the possible physical parameters are discussed that might help predict the degree of damage caused, but from this study it is not possible to define a limit which could be proposed as safe.