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We used sections of the Visible Human Project to construct a cranial model for use in the study of shooting injuries in forensic practice with a common information support (PC) at our disposal. The sections were applied on a grid model formed by the intersection of several orthogonal planes in space (Figure 1).
A wire frame of planes intersecting each other in the space at various heights was first made; the a texture made by DMSV, corresponding to a virtual anatomical section, was applied to each of them. The model was then finished in the wire frame and studied to define the anatomical correspondence of the structures and then the cardinal sections. For ease of use of the model, we prepared a database to store all the sections, according to the three axes of the space; each time, in the representation of the shooting injury, the significant ones are selected for representation in 3-D. For a realistic representation of the case subject to a forensic-medical investigation it was necessary to normalise the model to the morphological characteristics of the cranium affected by shooting injury. Compared to the traditional measurements adopted in forensic pathology, to use the model the distance from the craniometric punt nearest to the meridian and to the parallel intersecting each other in the injury has to be determined for each hole. This was achieved by using the following parameters: a) for bone structures, cranial measurements between the various craniometric points and related indices; b) the facial thickness of the cutaneous and subcutaneous integuments according to the Rhine and Moore Tables (Table 1).
The measurements thus obtained in each case were entered on the sections of the model, which was than adapted by using a photographic retouching program. On the model adapted to the case in point, we reproduced the shooting injures found during the autopsy, proceeding as follows: a) digitalisation of the photos of the entry and exit holes; b) normalisation of the relative measurements with those found on the corpse; c) virtual reconstruction of the trajectory described by the ballistic agent, by means of a cylinder with no base; d) positioning of the entry and exit holes on the cutis and the cranial theca, according to analytical geometry procedures, on the descriptive sections of the model in the space. The cylinder representing the path was created by starting with a standard model available in a CAD and adapting its basic circumference to the calibre of he bullet, if available, or to the dimensions of the entry hole hole. The cylinder height (length of the path) is set as standard and adapted later when the final graph obtained by rendering is produced. This operation is used to check the correspondence of the path (assumed as a straight line for intra-somatic routes not diverted by secondary impacts) with the entry and exit holes positioned according to the procedures described above. By way of example we show two cases of application of the project to an uxoricide, with points of view of the path both on the cutaneous and osseous plane (Figure 2, Figure 3, and Figure 4), and a suicide with emphasisation of the entry hole (Figure 5). This graphic processing make it possible: a) to obtain a three-dimensional representation of the intracranial path and the anatomical structures affected; b) to determine the spatial orientation of the path.. The procedure is carried out using tools and methodologies that are inexpensive, compared to imaging diagnosis procedures, and readily available hardware and software products. At present the developments of the project are: a) extension of the model to the whole human body (expected to be achieved by next October); b) animation of the model and insertion in the related crime scene by the use of an ad hoc software, initially on mainframe and later adapted to PC (if possible): this part of the project is in the preliminary feasibility study phase.
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