Implementation of the In-house Developed Wireless Visual Coaching System for Respiratory-Gated Stereotactic Body Radiotherapy in Liver Cancer Patient

Introduction

Stereotatic body radiotherapy on liver relies on real time position management (RPM) to monitor breathing motion. Regular and consistent breathing pattern is the key factor to achieve an accurate treatment delivery. The implementation of visual coaching system in SBRT liver patients during imaging and radiotherapy can link up the recognition for patient to reproduce a regular and consistence breathing motion. Meanwhile, it minimizes the dosimetric impact caused by irregular respiratory motion and maximizes the treatment efficiency in respiratory-gated liver tumour.

Objectives

To evaluate the in-house cost-efficient visual coaching system in respiratory-gated radiotherapy liver cancer patient.

Methodology

Six patients with SBRT liver were recruited in this study. 60 sets of respiratory breathing patterns under visual coaching display were compared with ten previously treated liver cancer patients without visual coaching display. The time engaged in training, CT, verification, and treatment were compared and evaluated. Patient was initially arranged to attend a training session. He/she was asked to lie on the same treatment set up and breath normally as usual. Real-time positioning management system was used to record the breathing period and breathing amplitude. After that, in-house wireless visual display was mounted on couch for patient to visualize his/her own breathing pattern under coaching. The breathing parameters were recorded again, and analysis was made for selecting the gating or free-breathing technique. During CT and radiotherapy session, those parameters were recorded again to evaluate the reproducibility of breathing pattern. All the patients were positioned by X-ray and treatment were performed within our planned breathing pattern.

Results & Outcome

The time used to acquire CT imaging of each patient was significantly reduced by 30% and consistency for CT planning was enhanced as well. With the consultation session and visual coaching display, the treatment failure rate due to the anatomical changes was significantly decreased from 25% to 10%. The usage of kilo-Voltage on-board imaging for patient positioning was reduced from an average of 5 to 3.1 times per treatment session. A more consistent and reproducible breathing pattern could be obtained with less imaging dose induced to patient.