Dosimetric advantages of respiratory gating technique in stereotactic radiotherapy of lung tumors
Objective To explore the advantages of respiratory gating technique in the target area and dosimetry of stereotactic radiotherapy(SBRT)for lung tumors.Methods 20 patients with primary or metastatic lung cancer treated at the radiotherapy center of the First Affiliated Hospital of Anhui Medical University were selected.All of them underwent 4D-CT scanning,and the scanning data were processed to obtain a total of 10 time-phase CT images.Two treatment plans were developed:a 30%to 70%time-phase respiratory gating plan and a full time-phase general radiotherapy plan.The internal target volume(ITV),planned target volume(PTV),target dose,volume,mean lung dose(MLD),V5,V20,V30,cardiac Dmax,spinal cord Dmax,esophageal Dmax and proximal bronchial tree Dmax were compared between the two plans.Results Compared with conventional radiotherapy plan,the ITV and PTV in respiratory gated plan was significantly smaller(P<0.05).The bilateral lung volume,MLD,V5,V20 and V30 under the respiratory gating technique plan were all significantly lower than those under the conventional radiotherapy plan(P<0.05).Subgroup analysis of lung metastases also re-vealed that all relevant dosimetric parameters of lungs under respiratory gating plan were smaller than those under the conventional ra-diotherapy plan(P<0.05).Conclusion Respiratory gating technology can be applied to stereotactic radiotherapy for early-stage non-small-cell lung cancer and lung metastases,significantly reducing the volume of the target area and normal tissue irradiation doses,and serves as an effective local treatment option for patients with lung metastases.
lung tumorrespiratory gating techniquestereotactic body radiation therapy4D-CT
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