The application of active respiratory gating technology in lung cancer radiotherapy

Objective: The technology of ABC ( Active Breathing Control) was used in breath-holding time in order to improve the accuracy of radiotherapy for lung cancer patients, and the influence of respiratory movement on diaphragm motion was analyzed and evaluated, in addition the feasibility and limitation of ABC was also assessed. Methods: 15 lung cancer patients were selected for the training of ABC, at the beginning of the training, let the patients practice breath-holding by themselves at home: the practice time is 30 minutes a day, one week practice, therefore the patients slowly adapted to the new breath-holding time, which is more than 40 seconds. In the CT scan and reset simulation, the images of ABC and FB( Free Breathing) were collected respectively; At the same time of precise radiation treatment, the error values between the CT images by using ABC system and the images of the real-time scans were collected. Results: The breath-holding time of the 15 patients were more than 40 seconds, and their average breath-holding time achieved 58.3 seconds, it is longer than that of the patients before training by 24.9 seconds. The diaphragm motion is reduced by 16.76mm than that of the free breathing. In the precise radiotherapy by using ABC, the average errors of left and right, head and feet , front and back were 0.29mm, 0.51mm, 0.49mm; After the bed displacement, the average errors were 0.08cm,0.18cm,0.15 cm. Conclusions: After using ABC system in the precise radiotherapy, the average error range of left and right, head and feet , front and back was within 2mm, and the respiratory diaphragm motion was smaller than before, so the radiation effect became more accurate, and this provided more protection for the patients.