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Introducción: En el tratamiento del Cáncer Cervico Uterino la braquiterapia (BQT) con planificación tridimensional (3D) está altamente extendida, aunque por su costo otros centros utilizan BQT con planificación bidimensional (2D). Es importante establecer si el beneficio que se obtiene con BQT en 3 D, en la protección a los órganos de riesgo, es un factor determinante para el cambio hacia esta nueva tecnología. El objetivo del estudio es comparar las dosis en ambos tipos de BQT en los órganos adyacentes al útero como el colon y vejiga. Métodos: El presente estudio descriptivo, incluye pacientes con diagnóstico de cáncer de cuello uterino que recibieron BQT en el período comprendido de enero 2015 a diciembre 2018, en el servicio Radioterapia del Hospital Solón Espinosa Ayala, Quito-Ecuador. Las variables fueron la dosis recibida con planificaciones en 2D y 3D. Se obtuvo histogramas dosis volumen de los órganos de riesgo: recto y vejiga. Se comparan los promedios con T de Student. Resultados: Participaron 44 casos, de 50.6 ±13.8 años de edad. En estadío clínico IIB 24 casos (55 %). La dosis prescrita de BQT en el grupo fue de 683.6 ±27 cGY. El tipo de aplicador usado fue en la gran mayoría AyT de 5 mm en 34 casos (77 %). La mayoría de los tratamientos consistieron en terapias de 4 sesiones 32 casos (73 %), con 117 implantes para BQT. La dosis planificada en vejiga en 2D fue 5.5 Gy, versus 5.1 Gy en 3D, P= 0.01. La dosis planificada en recto en 2D fue 2.8 Gy; versus 3.0 Gy en 3D P= 0.06. Conclusión: La planificación en 3D reduce significativamente 0.4 Gy la dosis irradiada a vejiga. En el caso del recto la dosis la dosis no produce cambios estadísticos respecto a planificación en 2D.

Introduction: In the treatment of Uterine Cervical Cancer brachytherapy (BQT) with three-dimensional planning (3D) is highly widespread, although for its cost other centers use BQT with two-dimensional planning (2D). It is important to establish if the benefit obtained with BQT in 3 D, in the protection of risk organs, is a determining factor for the change towards this new technology. The aim of the study is to compare the doses in both types of BQT in the organs adjacent to the uterus such as the colon and bladder. Methods: The present descriptive study includes patients diagnosed with cervical cancer who received BQT in the period from January 2015 to December 2018, in the Radiotherapy service of the Hospital Solón Espinosa Ayala, Quito-Ecuador. The variables were the dose received with 2D and 3D plans. Histograms were obtained volume volume of the organs at risk: rectum and bladder. The averages are compared with Student's T. Results: There were 44 cases, of 50.6 ± 13.8 years of age. In clinical stage IIB 24 cases (55%). The prescribed dose of BQT in the group was 683.6 ± 27 cGY. The type of applicator used was in the great majority AyT of 5 mm in 34 cases (77%). The majority of treatments consisted of therapies of 4 sessions 32 cases (73%), with 117 implants for BQT. The planned dose in 2D bladder was 5.5 Gy, versus 5.1 Gy in 3D, P = 0.01. The planned dose in rectum in 2D was 2.8 Gy; versus 3.0 Gy in 3D P = 0.06). Conclusion: 3D planning significantly reduces 0.4 Gy the dose irradiated to the bladder. In the case of the rectum, the dose does not produce statistical changes with respect to 2D planning.

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The International Atomic Energy Agency (IAEA) through the International Action Plan on Radiation Protection of Patients and the International Commission on Radiological Protection have for some time carried out important efforts to assure that in the medical applications of the ionising radiations, the optimisation of radiological protection of patients is fundamental, to such a point that the IAEA includes it directly as a requirement for these practices (in its International Basic Safety Standards for Protection against Ionising Radiation and for the Safety of Radiation Sources (BSS)-GSR Part 1, 2011). For this reason, among the objectives of Regional Project RLA/9/057 and Regional Project RLA/9/067, the intention was to establish the dose references in conventional radiology for Latin America, for the purposes of determining whether these doses comply with the requirements of the BSS and to tend to improve practices, in order to minimise the dose received by the patients.

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