Study of lung respiratory motion influence in patients undertake external beam radiotherapy

Abstract

Author(s): Yousif Abdallah*, Nouf Abuhadi, Elabbas Ebaid, Bahaeldin Atta, Abdulrahman M. Alzandi and Tariq Alqahtani

Objectives: The aim of this study is to investigate how respiration influences the motion of lung and pancreas tumours and to relate the observations to treatment procedures intended to improve dose alignment by predicting the moving tumour’s position from external breathing indicators. Methods: Breathing characteristics for five healthy subjects were observed by optically tracking the displacement of the chest and abdomen, and by measuring tidal air volume with a spirometer. Fluoroscopic imaging of five radiotherapy patients detected the motion of lung and pancreas tumours synchronously with external and internal breathing indicators. Results: The mean age of the patients in this study was 54.6+9.1 years. 70% of the patients were males and 30% were females. The external and fluoroscopic data showed a wide range of behaviour in the normal breathing pattern and its effects on the position of lung and pancreas tumours. This included transient phase shifts between two different external measures of breathing that diminished to zero over a period of minutes, modulated phase shifts between tumour and chest wall motion, and other complex phenomena. The lung tumour-motion results in this study were 4.8(0-9), 2.9(1.3-6.0), 3.8(1.7-8.2) mm for SI, AP and LR direction, respectively. Conclusion: Respiratory compensation strategies that infer tumour position from external breathing signals, including methods of beam gating and dynamic beam tracking, require three-dimensional knowledge of the tumour’s motion trajectory as well as the ability to detect and adapt to transient and continuously changing characteristics of respiratory motion during treatment

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