Reduction of Applicator Displacement in MR/CT-Guided Cervical Cancer High-Dose-Rate Brachytherapy By the Use of Patient Hover Transport System

Abstract

To quantify the reduction of relative displacement between the implanted intracavitary applicator and the patient, thanks to the use of a hover transport device during the patient transports between the imaging table and the treatment table. The displacement of the applicator inside the patient was measured by comparing the distance between the tip of the tandem and the pubic bone on x-ray radiography images taken before and after moving patient to MR/CT imaging. Displacements were evaluated for 27 fractions of treatment using hover transport and 185 fractions of treatment using manual transport. The mean applicator displacement is 3.41 mm (95% CI: [2.96, 3.97]) for manual transport fractions and 2.27 mm (95% CI: [1.71, 2.97]) for hover transport fractions. The reduction of applicator displacements for fractions using hover transport is statistically significant, compared to the manual transport method (p-value = 0.0086). The use of hover transport reduced the percentage of fractions with displacements greater than 5 mm from 22.70% to 7.40%. The displacement frequencies for the hover and manual transport methods are summarized in Table 1 below.Abstract 3746; Table 1Displacement Frequencies for Hover and Manual Transport MethodsDisplacement RangeHover Transport MethodManual Transport Method< 3mm74.1%59.5%3-5mm18.5%17.8%5-10mm7.4%18.9%> 10 mm0%3.8% Open table in a new tab This study indicates that the hover transport device is effectively reducing displacement between tandem and patient during patient transports, and therefore improving the accuracy of dosimetry in HDR treatment planning and delivery.