INVESTIGADORES
TIRAO German Alfredo
congresos y reuniones científicas
Título:
X-ray microtomography on birds: The access to an inadvertent world
Autor/es:
C.P. TAMBUSSI; G. TIRAO; F.J. DEGRANGE
Reunión:
Congreso; XIV Latin American Seminary of Analysis by X-ray Techniques ? SARX; 2014
Resumen:
The cranial cavity of birds
is almost completely filled by the brain, so the internal surface of the cranial
bones closely reflects brain anatomy including the blood vessel and nerves. 3D
models obtained from the CTs of skulls can be built for qualitative (cognitive,
sensory or ecological abilities) and quantitative (overall brain sizes or
particular brain areas) analysis. Conventional Hospital CT has been used quite extensively
to examine skeletal character and some soft tissues in bird [1 2] . However, it
is not possible to obtain good models of small specimens or deep details of
small structures such as the inner ear. X-ray microtomography opens the doors
to a completely empty space of knowledge so far. In Argentina, obtaining micro
CT is possible at National University of Córdoba. The x-ray micro-CT equipment
was entirely developed by researchers of Grupo de Espectroscopía Atómica y
Nuclear (GEAN) at Facultad de Matemática, Astronomía y Física (FaMAF). This
equipment allows to obtain 2D and 3D images up to 20 cm x 20 cm with
resolutions of 194 mm. It is also possible to maximize the quality of the images from the control
of main parameters involved in the image acquisition: conformation of the X-ray
beam (spatial and spectral distribution), counting statistics, number of projections,
relative position of the sample and detector. To evaluate the potential differences
of the models obtained with one or other equipment, specimens of Guira Cucko
(skull length 60mm) were scanned into two apparatus and virtual 3D models were
made with the same software (Materialise Mimics) and protocol. The model of the
micro-CT ( ~238 slices) allowed visualization of the dorsal parts of the brain
(wulst associated with proprioceptive abilities), the vascular system
(carotids), the cephalic nerves, pituitary and inner ear. From the latter it is
possible to calculate hearing capabilities. In the model constructed from the
conventional CT (~89 slices), these structures are no discernable. The
information obtained is valuable not only to better understand the animal
biology but to establish patterns of change and evolutionary rates in a
comparative context. Ultimately, the use of high resolution scanners has enormous
applications in biology and paleobiology.