Evaluación de Errores de Posicionamiento en los 6 Grados de Libertad en Pacientes con Cáncer de próstata tratados con radioterapia

Objectives: To determine the magnitude of the positioning errors in the 6 degrees of freedom and calculate the Margin to CTV for an adapted protocol in patients with early and locally advanced prostate cancer in a reference center in Colombia. Methods: A prospective observational study was performed in 61 prostate cancer patients treated with radiotherapy at the Javeriano Oncology Center of the San Ignacio University Hospital during 2018, with volumetric X-ray imaging during the first 3 days of treatment obtaining a average in translational and rotational errors. Subsequently, weekly images were taken. In addition, the calculation of the margin to the PTV and variations in bladder and rectum during the treatment was performed. Results: A total of 508 images were recorded during the 8 weeks of treatment, translational and rotational errors had a behavior around zero without significant differences even in patients with BMI > = 25. The margin to the PTV was also calculated between 5 and 8 mm, in terms of bladder and rectum measurements, no statistically significant differences were found in the images acquired during radiotherapy. Conclusions: According to the data found in this study, an adequate reproducibility in a patient with prostate cancer can be found using the method of rigid registration of the pelvic bone anatomy, averaging the first 3 images and subsequently with weekly images, in centers with high patient demand guaranteeing adequate treatment accuracy.