Experiencia argentina en la etapa final de erradicación de la polio: cambio de vacuna oral trivalente a bivalente / Argentinian experience to finish polio eradication: switch from trivalent to bivalent oral poliovirus vaccine

Entre el 17 de abril y el 1 de mayo de 2016, 155 países en todo el mundo cambiaron el uso de la vacuna oral trivalente, que protege contra los tres tipos de poliovirus (1, 2 y 3), por la vacuna oral bivalente, que protege contra los poliovirus tipo 1 y 3. Este cambio señala el mayor esfuerzocoordinado globalmente en la historia de las vacunas. En Argentina se realizó el pasado 29 de abril, con una intensa planificación previa y una posterior validación.

To evaluate the accuracy of dynamic versus static IMRT delivery using portal dosimetry.

INTRODUCTION: To evaluate the delivery accuracy of dynamic (DMLC) and static (SMLC) intensity modulated radiation therapy (IMRT) techniques using portal dosimetry (PD) in Varian Eclipse Treatment Planning System. MATERIALS AND METHODS: Seven DMLC IMRT Head and Neck plans were retrospectively generated for the study using SMLC mode at 20, 10 and 5 levels of intensity (SMLC20, SMLC10, SMLC5). Dosimetric verifications performed by PD on a total of 107 fields were evaluated using the gamma index (maximum (γmax), average (γavg), percentage of points with (γ%) ≤ 1). The images were acquired at a source-detector distance of 100 cm at gantry zero degree and also at clinically planned gantry angles. RESULTS: For both modes, measurements are within acceptable criteria. (γ%) ≤ 1 improves by increasing SMLC levels (+3.4 % from SMLC5 to SMLC20, p < 0.001) and using DMLC (+3.9 % and +0.6 % compared to SMLC5 and SMLC20, respectively, p < 0.001). Also (γmax) parameter improves significantly by increasing SMLC levels (+22 % from SMLC5 to SMLC20) and using DMLC (+34 % and +16 % compared to SMLC5 and SMLC20, respectively). The effect of the gantry rotation influences the delivery accuracy by up to -7 % (p < 0.05). The effect of leaves travelling direction was almost negligible (1 %). CONCLUSIONS: A good agreement between calculated and measured fluences was obtained for DMLC and SMLC techniques at higher intensity levels; however, DMLC delivery ensures the best reproduction of computed fluence maps. The gantry rotation influences the delivery accuracy in particular for SMLC modes at lower intensity levels.

The impact of computed tomography slice thickness on the assessment of stereotactic, 3D conformal and intensity-modulated radiotherapy of brain tumors.

PURPOSE: To evaluate radiotherapy treatment planning accuracy by varying computed tomography (CT) slice thickness and tumor size. METHODS: CT datasets from patients with primary brain disease and metastatic brain disease were selected. Tumor volumes ranging from about 2.5 to 100 cc and CT scan at different slice thicknesses (1, 2, 4, 6 and 10 mm) were used to perform treatment planning (1-, 2-, 4-, 6- and 10-CT, respectively). For any slice thickness, a conformity index (CI) referring to 100, 98, 95 and 90 % isodoses and tumor size was computed. All the CI and volumes obtained were compared to evaluate the impact of CT slice thickness on treatment plans. RESULTS: The smallest volumes reduce significantly if defined on 1-CT with respect to 4- and 6-CT, while the CT slice thickness does not affect target definition for the largest volumes. The mean CI for all the considered isodoses and CT slice thickness shows no statistical differences when 1-CT is compared to 2-CT. Comparing the mean CI of 1- with 4-CT and 1- with 6-CT, statistical differences appear only for the smallest volumes with respect to 100, 98 and 95 % isodoses-the CI for 90 % isodose being not statistically significant for all the considered PTVs. CONCLUSIONS: The accuracy of radiotherapy tumor volume definition depends on CT slice thickness. To achieve a better tumor definition and dose coverage, 1- and 2-CT would be suitable for small targets, while 4- and 6-CT are suitable for the other volumes.

Planning target volume assessment in lung tumors during 3D conformal radiotherapy by means of an aSi electronic portal imaging device in cine mode.

PURPOSE: The major uncertainties in treating lung cancer are the repositioning errors and respiratory lung tumor motion. Typically, margins are added to the clinical target volume (CTV) to obtain a planning target volume (PTV) allowing the accommodation of such uncertainties. We want to test a new technique to assess the adequacy of the chosen PTV using an aSi electronic portal imaging device (EPID). METHODS: Four patients affected by lung cancer and treated by radical 3D conformal radiotherapy (3DRT) were studied. During treatment the EPID was used in cine mode acquisition: acquired images were used to the aim. RESULTS AND CONCLUSIONS: Treatment monitoring with an EPID in cine mode is shown to be a clinically feasible and useful tool.

[Endemic corridors: a useful tool for the epidemiological surveillance of influenza]. / Corredores endémicos: una herramienta útil para la vigilancia epidemiológica de la influenza.

Epidemiological surveillance provides updated information about health problems which allows for the establishment of health policy guidelines. The methods for detecting the epidemic frequency of disease require the systematic collection of data on the occurrence of specific diseases. Influenza has cyclic seasonal peaks and its endemic baseline rates are useful for identifying outbreaks: the comparison between baseline and current data supplies epidemiological evidence related to an ongoing outbreak. The upper and lower incidence curves were traced for the data referring to IA detection in the nasopharyngeal aspirates from children hospitalized for acute lower respiratory tract infection from 1996 to 2002. The arithmetic mean and the 95% confidence interval for upper and lower limits of weekly incidence were calculated. The highest incidence was observed between weeks 25 and 32. When analyzing the prepared endemic corridor, it was observed that the highest detection in 2003 occurred between weeks 19 and 25, whereas two peaks occurred in 2004, the first starting at week 20, at a lower level than the normal epidemic peak, and the second at week 26.

Corredores endémicos: Una herramienta útil para la vigilancia epidemiológica de la influenza / Endemic corridors: a useful tool for the epidemiological surveillance of influenza

La vigilancia epidemiológica provee información actualizada y oportuna sobre los problemas de salud y sus condicionantes, lo que permite definir acciones de prevención y control. Para la detección de epidemias es útil disponer de corredores endémicos, que indican el número de casos esperados para un cuadro infeccioso en un momento determinado. Con datos de la sección Microbiología del Hospital de Niños "Dr. Pedro de Elizalde" acerca de pacientes internados con diagnóstico de infección respiratoria aguda baja (IRAB) entre el 1/1/96 y el 31/12/2002 se confeccionaron los corredores para influenza A (IA) por semanas epidemiológicas, correspondientes a un período de siete años. En ese período se internaron 10.473 niños con diagnóstico de IRAB y se identificó IA en 411 aspirados nasofaríngeos. Se calcularon la media y el intervalo de confianza de 95% para los límites superior e inferior de incidencia en períodos semanales, y se encontró que el pico estacional ocurre entre las semanas 25 y 32. Al analizar los datos del año 2003, se observó que el pico se produjo antes, entre las semanas 19 y 25, y con valores muy por encima de los esperados para esas semanas. En 2004 aparecen 2 picos, el primero en la semana 20 y sin superar los valores de fluctuación de la parte central de la curva, y el segundo en la semana 26.

Epidemiological surveillance provides updated information about health problems which allows for the establishment of health policy guidelines. The methods for detecting the epidemic frequency of disease require the systematic collection of data on the occurrence of specific diseases. Influenza has cyclic seasonal peaks and its endemic baseline rates are useful for identifying outbreaks: the comparison between baseline and current data supplies epidemiological evidence related to an ongoing outbreak. The upper and lower incidence curves were traced for the data referring to IA detection in the nasopharyngeal aspirates from children hospitalized for acute lower respiratory tract infection from 1996 to 2002. The arithmetic mean and the 95% confidence interval for upper and lower limits of weekly incidence were calculated. The highest incidence was observed between weeks 25 and 32. When analyzing the prepared endemic corridor, it was observed that the highest detection in 2003 occurred between weeks 19 and 25, whereas two peaks occurred in 2004 , the first starting at week 20, at a lower level than the normal epidemic peak, and the second at week 26.

[Meningococcal meningitis:descriptive study of 76 cases in a pediatric hospital]. / Meningitis meningocócica: estudio descriptivo de 76 casos en un hospital pediátrico.

BACKGROUND: One of the principal causes of bacterial meningitis (BM) in children older than one month is Neisseria meningitidis (Nm). A quick diagnosis and an immediate treatment are considered essential for a good outcome. We propose this study with the purpose of evaluating the clinical and epidemiological characteristics of the patients with BM caused by Nm and analyzing the effect on the presentation and incidence of sequelae and/or complications of the time elapsed since the starting of symptoms and the beginning of the treatment. METHODS: We performed a retrospective analysis of the clinical registers of 76 patients diagnosed as BM caused by Nm entered in the Hospital de Pediatria Pedro de Elizalde, Buenos Aires, Argentina, during the years 1992 and 1993. We investigated age, sex, date of entrance, first symptoms, biochemistry of cerebrospinal fluid (CSF), nutritional status, convulsions and/or complications, length of internation and conditions at discharge. Processing was done with Epi-info 5.0. Differences between qualitative variables were analyzed with chi 2 and differences between means with z-test. RESULTS: Boys were majority; fever was the most frequent initial symptom; petechiae were less frequently found, specially among infants. 79% of the patients had CSF of purulent characteristics; 32.9% of the patients had complications during their evolution; its incidence raised up to 48% in infants. Lethality was 1.3%, 6.5% of the children had sequelae at the moment of discharge. The average time of internment was 13 days. There were no significant differences when different groups were compared according to their prior evolution time. CONCLUSIONS: 1) Petechiae and vomits were significantly less frequent in infants; 2) the incidence of complications was significantly higher in this last group; 3) no greater incidence of complications or sequelae was observed in patients whose previous period of evolution was longer than 48 hours; 4) in all groups of age we found insidious forms of starting, and 5) there were patients with CSF of normal biochemical characteristics in all groups considered independently of the time of evolution elapsed.