Tomograph for applications in the area of Pharmaceutical Sciences

Abstract

The Computed Tomography (CT) by transmission of x-rays or gamma became possible to view the interior of objects, without the need to open them physically. This technique was originally developed for the analysis and diagnosis of the human body, however, its use outside the medical field, in the non-destructive evaluation of materials, has increased. CT is a technique for obtaining images of sections of objects by measuring the intensity of transmitted radiation in different directions. The major contribution provided by a CT image is its ability to distinguish regions with different attenuation coefficients or densities and thereby separate superimposed structures, which in the most cases would not be visible, if it was made only a conventional radiography. CT is a powerful tool used in nondestructive physical tests and can be used, in principle, in any area of science. In the 90's, more precisely in 1997, after approval of the aid FAPESP (Proc. No. 97/06576-7), it was created the Laboratory of Applied Nuclear Physics of Uniso (LAFINAU). Among the many studies conducted since 1997, which brought more challenges for us was the design, construction and test of a system for generating tomographic images, called the Mini Computerized Tomograph of Uniso (MTCU). This equipment operates with a single detector of NaI(Tl) and uses radiation from a radioactive source of 241Am, i.e., is a scanner of 1st generation. The construction of this device enabled the group to gain experience in this area and develop a range of tools used in computed tomography, since part of the data acquisition programs until the routines necessary for the reconstruction of tomographic images. This scanner worked perfectly, but being a 1st generation device, took too long to generate a tomographic image of a plane of the object and it had low spatial resolution and in density. In 2005, we request new aid to FAPESP (Proc. No. 2005/04727-6) for construction of a 3rd-generation CT scanner, where the gamma-ray source of 1st generation tomograph was replaced by an X-ray source and the detector of NaI(Tl) was replaced by a line of photodiodes of silicon, containing 512 detectors, sensitive to X-rays, i.e., we build a 3rd-generation CT scanner. This scanner is installed on LAFINAU and is in full operation. With this device, the generation of a tomographic imaging was more rapid and there was a considerable gain in the quality of information (spatial resolution). However, this device, due to the detection system used (line of photodiodes), generates images of only one plane of the object at a time (image 2D). Whereas to develop cutting-edge research in any field of knowledge, we need fast, high-quality and accurate answers, thus, the obtaining of three-dimensional images (3D) of the interior of the objects are essential. Taking this into account and considering that to obtain a 3D image we need to acquire a series of 2D images, the realization of these images with the tomograph 3rd generation of Uniso is not feasible, because a 3D image with low spatial resolution, can take days or even weeks to be made. In Brazil, we are the only group that uses CT images in the study of physicochemical properties of solid dosage forms and excipients, and to have extensive experience in CT, we are requesting funds to FAPESP to purchase one tomograph of 3rd generation, capable of generating three-dimensional tomographic images. The acquisition of this equipment will enable our group to conduct cutting-edge research in the field of pharmaceutical sciences. (AU)