RESUMEN
Purpose: The addition of interstitial (IS) needles to intra-cavitary (IC) brachytherapy applicators is associated with improved outcomes in locally advanced cervical cancers involving parametrial tumor extensions. The purpose of this work was to validate a clinical workflow involving 3D-printed caps for a commercial IC split ring applicator that enable using IS needle trajectories tailored to each treatment. Material and methods: A dedicated software module was developed in this work allowing users to design patient-specific IS caps without knowledge of computer-aided design (CAD) software. This software module was integrated to 3D Brachy, a commercial software developed by Adaptiiv Medical Technologies Inc. For validation of the workflow, CAD models of ground truth caps with five IS needle trajectories were designed with Fusion 360™, 3D-printed, assembled with a split ring applicator, and CT-scanned with radio-opaque markers. 3D Brachy was then applied to generate a replica based on trajectories reconstructed from the radio-opaque markers. A comparison between ground truth and replicated IS needle trajectories was done using intersection points with planes at the level of the cervix (z = 0 cm) and a representative needle depth (z = 3 cm). Results: Prototypes of interstitial caps 3D-printed in both BioMed Amber and BioMed Clear SLA resins were tested to be functional both pre- and post-sterilization for IS needles with obliquity angles ≤ 45°. Distance-to-agreement at z = 0 cm and 3 cm as well as deviations in pitch and yaw angles of the five IS needle trajectories were found to have mean values of 3.3 ±2.1 mm, 7.3 ±2.0 mm, 2.9° ±2.3°, and 7.0° ±7.0°, respectively. Conclusions: The clinical workflow for image-guided adaptive cervical cancer brachytherapy using the Montreal split ring applicator was validated.
RESUMEN
AIM: Accurate preoperative staging is essential in determining optimal therapeutic procedures and planning for individual patients. Advances in imaging technology have raised interest in the potential role of positron emission tomography-computed tomography (PET-CT) examination for staging of rectal cancer. The primary end point of the study was the correct classification of the tumor node-metastases (TNM) tumor stage using whole-body PET-CT examination. METHODS: This prospective study was performed from October 2011 to October 2012. Patients with histopathological diagnosis of rectal cancer after biopsy underwent PET-CT before surgical treatment and TNM staging. Twenty patients who fulfilled inclusion criteria were included in the study. All of the patients were operated and histopathology served as the standard of reference. RESULTS: There was no statistical significance in T staging comparing PET-CT and histopathological staging, according to the Monte Carlo simulation (p=.066). Also, there was no statistical significance between two methods in mesorectal fascia involvement analysis (p=1). There was statistical difference between PET-CT and histopathological staging. Sensitivity of the PET-CT for N staging was 86.7% and it was higher than for the histopathology. Two patients showed liver metastases. CONCLUSION: Positron emission tomography-computed tomography examination could play an important role in the initial staging for the rectal cancer. Good patient selection for preoperative chemoradiotherapy ensures survival benefit. Avoidance of unnecessary therapeutic procedures allows an acceptable quality of patient's life.
