[en] In this work, a calibration curve was obtained to be used in experimental dosimetry studies for the treatment of keloids and skin cancers using high dose rate brachytherapy. With future impacts being related to improving the evaluation of radiotherapy plans by the multidisciplinary team. Due to the effects of radiotherapy being dose dependent, the best way to evaluate the result of a treatment is to ensure that the prescribed dose was absorbed by the patient. With the results in hand, it is possible to evaluate the radiotherapy treatment protocols used, increase the effectiveness of treatments, and improve the expected results

[en] Starch is a polysaccharide formed by the union of α-glucose molecules of amylose and amylopectin, and is stored in different plant organs. It has been used as an important ingredient in the food and non-food industries, with diverse applications due to its low cost and biodegradability. To expand its use, modifications to natural starch have been studied to make it suitable for each specific application. A processing technique that can be used to modify materials is exposure to high doses of gamma radiation. Starch has already been subjected to gamma irradiation in previous studies, but usually at low doses (below 100 kGy). In order to increase knowledge about the effect of gamma radiation on starch structure, samples of natural starch (Starch), waxy starch (WX) and cationic waxy starch (WX Cat) were irradiated with 500 kGy. The samples were irradiated in the Gamma Irradiation Laboratory of the Center for the Development of Nuclear Technology (CDTN), which has a panoramic irradiator equipped with a Cobalt-60 source. The materials were evaluated before and after irradiation through the techniques of Fourier-transform infrared spectroscopy (Ftir), Scanning electron microscope (Sem) and thermal gravimetric analysis (TGA). Lugol's iodine test was performed to qualitatively evaluate the relationship between amylose and amylopectin in the samples. The Ftir made it possible to characterize and compare the starches studied. Sem analysis demonstrated the effects of irradiation on starch morphology. The TGA results indicate an increase in residue in the irradiated samples, which may be related to the formation of radiation-induced cross-links. Lugol's iodine test showed that the prevalence of amylopectin in the composition of waxy starches was maintained. (author)

[en] Brachytherapy is a modality of radiotherapy that uses radioactive sources positioned inside tumors or at a short distance from them. The applicators that lead the source of radiation to the tumor must undergo strict quality control and dosimetry. The objective of this work is to make dosimetric evaluation and attenuation properties of an applicator developed for the treatment of skin lesions. The applicator consisting of 15 synthetic material spheres was designed and developed. The material was evaluated to study its composition and theoretical attenuation to gamma radiation. For this, the technique of Fourier-transform infrared spectroscopy (Ftir) and thermal gravimetric analysis (TGA) were used. The dosimetric evaluation was performed using an Ir-192 source from an HDR equipment, Gafchromic™ EBT3 radiochromic films, Gammex® 457 solid water phantom and an applicator. OncentraBrachy 3D version 4.3 was used. To read the films, an Epson Expression®10000-XL scanner and ImageJ and Origin® software were used for data acquisition and processing. The irradiations were performed with a dose of 500 c Gy on the surface of the applicator as prescribed for the treatment of skin lesions. The material of the spheres with a density close to that of water was identified. The applied dose distribution was evaluated in a length of 10 cm. It was possible to observe that the dose value in the center of the applicator corresponded to the prescribed dose of 500 c Gy. This demonstrates that the applicator does not interfere with the prescribed dose to be delivered to superficial lesions. (author)