Can SGRT be a Substitute for Plan Verification Procedure?

Abstract

Verification of plan (VP) has been part of our pre-treatment workflow for treatment isocenter verification. Currently, our center uses simulator for VP procedure for all our patients before the treatment. We would like to investigate if SGRT could be a good substitute for VP procedure to simplify our pre-treatment workflow. In Group A (A-c, A-t, A-a), 20 patients of each treatment site (cranial, thorax and abdomen) were selected randomly. Patients did not go through VP procedure. During the first fraction of treatment, the therapists were guided by SGRT system (Vision RT, UK) and aligned the patient to 3mm and 1°using a standard region of interest (ROI). First CBCT was taken as a reference to customize the ROI for better suitability. Next, the patient was re-aligned to 1mm and 1°using the new ROI. Second CBCT was acquired, and 6 degrees of freedoms shifts were recorded. In Group B (B-c, B-t, B-a), 20 patients of each treatment site (cranial, thorax and abdominal) that were assigned for VP over the same period as Group A patients. Group B patients were aligned based on the skin markings drawn during VP procedure. CBCTs were taken at the first fraction of treatment and shifts were recorded. A total of 60 CBCT images were analyzed for each group of patients. The absolute mean and standard deviations were shown in Table 1. The results indicated that Group A is superior, if not comparable, to Group B. Table 1: The absolute mean and standard deviations of first fraction of CBCT positioning errors for Group A and B patients. With appropriate ROI, SGRT is a good or superior substitute for plan verification procedure. Localization verification can be done during day one of treatment which ease the pre-treatment workflow to both patients and clinical team. Analysis of customized ROI will be further studied in the future.