Application Of Active Breathing Control And Dosimetric Analysis For Non-small Cell Lung Cancer

The lung tumors can show significant respiration-induced motion, which is differed variously among patients. To ensure sufficient target dose coverage, IM and SM should be added to the CTV to make up the PTV. Therefore, using a PTV including more surrounding tissue may either increase the NTCP or result in limitation of dose escalation. The technique of ABC can control the tumor mobility to reduce the margin, which may increase the TCP and decrease the NTCP. This study was designed to image, plan, and delivery of radiotherapy for patients with NSCLC using ABC, and to evaluate the geometric and dosimetric benefits and the clinical impact.Five patients with NSCLC were selected to performed 4D-CT and ABC-CT scanning, and 4 patients were irradiated using the ABC technique. The 4 patients were tolerated well with ABC except one patient. The movement of diaphragm was 13.0±4.1mm with FB, however, it decreased to 3.5±0.9mm (intrafraction) and 3.9±1.7mm (interfraction) with ABC. Though the GTVs differed slightly, the PTVs differed significantly, which is 241.6±22.1cm3, 172.7±16.7cm3, and 184.0±10.3cm3 in PTVFB, PTV4D, and PTVABC respectively. The lung's V20 was 22.6%, 19.9%, and 19.0% in FB, 4D, and ABC plan respectively.Radiotherapy using ABC for patients with NSCLC is feasible, with reduced diaphragm movement. The interfraction reproducibility is inferior to intrafraction reproducibility. Compared with FB plan, the ABC plan could reduce the target volumes and decrease the irradiation dose to lung, however, the difference is negligible in comparison to 4D plan.