2024-03-28T17:37:57Zhttps://bibdigital.epn.edu.ec/oai/requestoai:bibdigital.epn.edu.ec:15000/187592019-04-08T03:42:50Zcom_15000_18757com_15000_7554com_15000_7553com_15000_1col_15000_18758
Molineros Salgado, Carlos Daniel
2017-09-04T14:10:12Z
2017-09-04T14:10:12Z
2017-09-04
Molineros Salgado, C. D. (2017). Estudio de la relación entre la distribución espacial de la actividad de iodo 131 y la distribución de intensidades en la imagen SPECT/CT correspondiente. 80 hojas. Quito : EPN.
T-MVE/0596/CD 8147
http://bibdigital.epn.edu.ec/handle/15000/18759
In this work, all the processes related to the formation of the image of a NEMA/IEC phantom with a Siemens Simbia Intevo Excel SPECT/CT scanner were simulated using Monte Carlo simulations. Based on these simulations a method that allows the determination of the tridimensional distribution of the activity inside the phantom from on its SPECT/CT images was developed. The first simulated process was the emission of photons from the voxelized phantom filled with known activites of iodine-131, the detection of this photons in the gamma camera’s detector crystals, and the image production. The projections obtained were corrected, reconstructed and fused to the tomographic images. The method developed was validated with an experimental setup equivalent to the simulated one. In the experiment each container in the phantom was loaded with 131I so that the activities were known for each image acquisition. From the comparison between the simulation and the experiment, it was concluded that the method developed is suitable for activities lower than 2mCi contained in volumes greater than the machine’s resolution volume (1800mm3), in these conditions the method has a estimation error lower that 10 %.
spa
openAccess
MEDICINA NUCLEAR
METODOS MONTECARLO
FISICA MEDICA
Estudio de la relación entre la distribución espacial de la actividad de iodo 131 y la distribución de intensidades en la imagen SPECT/CT correspondiente
masterThesis
oai:bibdigital.epn.edu.ec:15000/194902019-04-08T01:38:59Zcom_15000_18757com_15000_7554com_15000_7553com_15000_1col_15000_18758
Pallaroso Yela, Mayra Alejandra
2018-06-25T22:14:48Z
2018-06-25T22:14:48Z
2018-06-25
Pallaroso Yela, M. A. (2018). Efecto del material de contraste en las distribuciones de dosis asociadas a la braquiterapia de alta tasa con Iridio-192 para tratamientos del cáncer cérvico-uterino. 73 hojas. Quito : EPN.
T-MVE/0681/CD 8888
http://bibdigital.epn.edu.ec/handle/15000/19490
The effect in the doses distributions associated to cervical-uterine cancer treatments with high dose rate brachytherapy with Iridium-192 produced by the contrast material was quantified. This was done by the calculation of doses with the Acuros algorithm implemented in the Brachyvision planning system. For the calculations the CT numbers (Hounsfield units) associated with the electronic density of the bladder with different concentrations of contrast were identified which were from 0 % (0 HU, equivalent to water) to 10 % (316.18 ± 94 HU) and 236 points around the implant were located, 41 of which were inside the bladder. For each of these points the deviation of the dose was calculated in the presence of contrast in the bladder with respect to the dose in the presence of water. For 500 HU, the deviations were up to 0.10 % for points outside the bladder and up to 2.21 % for points within the bladder. For the optimum concentration for imaging of 8 %, the absorbed dose in a volume of 2 cm3 of the bladder, would be up to 0.44 % higher dose than dose for water. The increment in absorbed dose lies within the tolerances established in radiotherapy.
spa
openAccess
DOSIMETRÍA
FÍSICA
RADIACIONES IONIZANTES
Efecto del material de contraste en las distribuciones de dosis asociadas a la braquiterapia de alta tasa con Iridio-192 para tratamientos del cáncer cérvico-uterino
masterThesis
oai:bibdigital.epn.edu.ec:15000/200922019-04-08T11:14:30Zcom_15000_18757com_15000_7554com_15000_7553com_15000_1col_15000_18758
García Navas, Jorge Humberto
2019-02-27T15:02:16Z
2019-02-27T15:02:16Z
2019-01-02
García Navas, J. H. (2019). Evaluación del deterioro de la calidad del tomógrafo Siemens Emotion 6 del Hospital SOLCA Núcleo-Quito y su influencia en las dosis y calidad de imagen. 64 hojas. Quito : EPN.
T-MVE/0730/CD 9561
http://bibdigital.epn.edu.ec/handle/15000/20092
In this study, the dose variation and the image quality of the Siemens Emotion 6 computed tomograph during the life time of the X-ray tube was evaluated. For this, five clinical protocols for both adult and pediatric patients were studied. The evolution of the doses in the center of a CTDI phantom, the modulation transfer function (MTF) and the noise power spectrum (NPS) in the ACR phantom was studied, the latter is a measurement of the image quality and we found that, with 95% of confidence, it does not exist correlation between dose and time neither between time and the image parameters. The X ray tube state was monitored with the evaluation of the beam characteristics, that is, the measurement of the hemyreductive layer (HVL) decreased a maximum of 0.158 mmAl for 110 kV and 0.267 mmAl for 130 kV, in agreement of the tolerance limits of the quality control protocols in tomography, the distribution of the kerma in air along both the rotation axis of the tomograph and the transverse axis during the study is less than 8% with respect to the mean value. Therefore, the normal deterioration of the equipment during the life time of the X ray tube will not significantly afect the medical diagnosis.
spa
openAccess
TOMOGRAFÍA COMPUTARIZADA
TRANSFERENCIA DE MODULACIÓN
Evaluación del deterioro de la calidad del tomógrafo Siemens Emotion 6 del Hospital SOLCA Núcleo-Quito y su influencia en las dosis y calidad de imagen
masterThesis