Development of a Breathing Monitor and Training System, And the Analysis of Methods of Training Patients to Regulate their Breathing when Undergoing Radiotherapy for Lung cancer
Purpose: Advanced radiotherapy treatments for Non-Small-Cell Lung Cancer (NSCLC) rely on conforming the radiation dose to the tumour geometry as tightly as possible; this increases the probability of killing the tumour cells while simultaneously reducing the radiation dose to nearby tissues and to organs at risk, subsequently reducing normal tissue reactions. Unfortunately, patient breathing is likely to compromise the method during implementation, as the breathing motion causes the tumour to move periodically out of the path of the radiation beam, while normal, healthy tissue periodically moves into the line of the beam. The aim of this project is to establish a simple breath-monitoring system which is inexpensive, easy to use and patient friendly; this could be achieved by developing a device that is considered to be non-invasive, and which also does not rely on connections to the treatment machine; it is based on a simple instrumented belt using strain-gauges which monitor the chest-to-wall motion during the breathing cycle. Methods and Materials: A total of fifty volunteers participated in this study. Three methods of breathing were used: free-breathing, audio-prompted breathing and visual feedback breathing, with synthesised breathing as the ‘ideal’ pattern. The breathing monitor was used in order to investigate the difference between various training regimes for helping subjects to modify their breathing patterns into a desirable pattern. Results: The results show that audio prompting — the method most commonly used in the clinic to date — was the least effective of the methods tested, resulting in large amplitude and phase variations compared to the other methods. Visual feedback (not currently used) is demonstrated as being far superior in regulating a subject’s breathing: this method produces far tighter control over both the amplitude and phase of the breathing pattern in comparison to any other method investigated. Conclusions: It is concluded that the current methods of regulating breathing in patients undergoing radiotherapy for lung tumours are inappropriate, and that a far better approach would be to use visual feedback.
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