A multi-centric evaluation of self-learning GAN based pseudo-CT generation software for low field pelvic magnetic resonance imaging

Purpose/objectivesAn artificial intelligence-based pseudo-CT from low-field MR images is proposed and clinically evaluated to unlock the full potential of MRI-guided adaptive radiotherapy for pelvic cancer care.Materials and methodIn collaboration with TheraPanacea (TheraPanacea, Paris, France) a pseudo-CT AI-model was generated using end-to-end ensembled self-supervised GANs endowed with cycle consistency using data from 350 pairs of weakly aligned data of pelvis planning CTs and TrueFisp-(0.35T)MRIs. The image accuracy of the generated pCT were evaluated using a retrospective cohort involving 20 test cases coming from eight different institutions (US: 2, EU: 5, AS: 1) and different CT vendors. Reconstruction performance was assessed using the organs at risk used for treatment. Concerning the dosimetric evaluation, twenty-nine prostate cancer patients treated on the low field MR-Linac (ViewRay) at Montpellier Cancer Institute were selected. Planning CTs were non-rigidly registered to the MRIs for each patient. Treatment plans were optimized on the planning CT with a clinical TPS fulfilling all clinical criteria and recalculated on the warped CT (wCT) and the pCT. Three different algorithms were used: AAA, AcurosXB and MonteCarlo. Dose distributions were compared using the global gamma passing rates and dose metrics.ResultsThe observed average scaled (between maximum and minimum HU values of the CT) difference between the pCT and the planning CT was 33.20 with significant discrepancies across organs. Femoral heads were the most reliably reconstructed (4.51 and 4.77) while anal canal and rectum were the less precise ones (63.08 and 53.13). Mean gamma passing rates for 1%1mm, 2%/2mm, and 3%/3mm tolerance criteria and 10% threshold were greater than 96%, 99% and 99%, respectively, regardless the algorithm used. Dose metrics analysis showed a good agreement between the pCT and the wCT. The mean relative difference were within 1% for the target volumes (CTV and PTV) and 2% for the OARs.ConclusionThis study demonstrated the feasibility of generating clinically acceptable an artificial intelligence-based pseudo CT for low field MR in pelvis with consistent image accuracy and dosimetric results

Hugo Chávez: una década en el poder

Una década de Hugo Chávez Frías y su proyecto político en Venezuela trajo consigo un cambio de paradigmas que llama la atención de la sociedad en general. Este libro es el resultado del esfuerzo conjunto de un grupo de académicos de distintas nacionalidades que desde sus líneas de investigación realizan análisis que le brindan al lector elementos para comprender de manera global lo que significa una década de gobierno del Presidente Chávez en Venezuela.Este libro es el resultado del esfuerzo conjunto de un grupo de académicos de distintas nacionalidades que desde sus líneas de investigación realizan análisis que le brindan al lector elementos para comprender de manera global lo que significa una década de gobierno del Presidente Chávez en Venezuela

Un balance de la seguridad alimentaria y nutricional en Venezuela 2000-2020

Venezuela está atravesando procesos de decrecimiento económico lo que profundiza la crisis alimentaria y aumenta la violencia. Venezuela está viviendo la mayor crisis institucional, social, económica, política, moral, cultural de su historia, lo que incluye la pérdida de su capital humano por motivos de la emigración masiva y forzosa habida en los últimos años y también por la violencia, inseguridad ciudadana, por el incremento de la desigualdad social y la destrucción del Estado de Derecho. La crisis venezolana es una crisis de carácter multidimensional, la más profunda, compleja y larga de su historia moderna cuyas causas tienen que ver con la erosión continua de la institucionalidad, la pérdida progresiva de los valores democráticos, con el desdibujamiento del Estado y con el auge de un populismo autocrático que viola constantemente los principales derechos humanos. Ello sucede sin que en el país haya habido desastres naturales o conflictos bélicos. Los diversos programas sociales dirigidos a la soberanía alimentaria implementados durante las dos últimas décadas estuvieron atados a la volatilidad de los precios petroleros. Por otra parte, presentan un descuido extremo en cuanto a la calidad institucional de su gestión, se caracterizan por una acrecentada tendencia hacia la inefectividad y un agravamiento de la desprofesionalización de la administración pública. Ausencia de planificación y de evaluación desnudan las grandes y graves limitaciones de la gran mayoría de estos programas. Hoy en día el país está sumido en una crisis humanitaria compleja que ya lleva 5 años sin perspectivas claras de progreso.Venezuela is going through a process of economic decline, which is deepening the food crisis and increasing violence. Venezuela is experiencing the greatest institutional, social, economic, political, moral and cultural crisis in its history, which includes the loss of its human capital due to massive and forced emigration in recent years, as well as violence, citizen insecurity, increased social inequality and the destruction of the rule of law. The Venezuelan crisis is a multidimensional crisis, the deepest, most complex and longest in its modern history, the causes of which have to do with the continuous erosion of institutions, the progressive loss of democratic values, the blurring of the state and the rise of an autocratic populism that constantly violates the main human rights. This is happening without any natural disasters or armed conflicts in the country. The various social programs aimed at food sovereignty implemented over the last two decades have been tied to the volatility of oil prices. On the other hand, they show extreme neglect in terms of the institutional quality of their management and are characterized by an increased tendency towards ineffectiveness and a worsening of the de-professionalization of public administration. The absence of planning and evaluation reveal the great and serious limitations of the vast majority of these programs. The country is currently in the midst of a complex humanitarian crisis that has been going on for five years with no clear prospects for progress