Objective To study corrective method for displacement in the procedure of electronic portal imaging device (EPID)-based intensity-modulated radiotherapy dose valuation by studying the relative mechanical displacement of different vendor EPID (aS1000,Varian; aS500,Varian; iViewGT,Elekta).Methods A 5 cm × 5 cm field was set up to acquire portal images for three kinds of EPID,then a in house software was used to analysis the portal images.The relative displacement was acquired via analyzing a series of comparation between center positions of gantry angle ranging from 0° to 360° and gantry angle at 0°.Results In the lateral direction,the maximum relative displacement of EPID with aS1000,S500 and iViewGT were (-0.23 ±0.17) mm,(2.94±0.17) mm and (0.35 ±0.09) mm,respectively.In the longitude direction,the displacements were (-4.16 ± 0.20) mm,(-4.15 ± 0.25) mm and (-1.66 ±0.11) mm,respectively.As to longitude direction,the displacements could be well fitted with the usage of quadruplicate empiric function.Conclusions There is a significant difference at the aspect of relative displacement between different vendors EPID at different gantry angles.And the displacement in the longitude direction is obviously larger than in the lateral direction.The relative displacement should be corrected when applying EPID to the intensity-modulated radiotherapy dose verification at different gantry angles.

Objective     To explore the timing and safety of limited-period lung cancer surgery in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Methods     Clinical data of of patients infected with COVID-19 undergoing lung cancer surgery (an observation group) in the Department of Thoracic Surgery of Guangdong Provincial People's Hospital, the Department of Thoracic Surgery of General Hospital of Southern Theater Command of PLA, and the Department of Cardiothoracic Surgery of the First Affiliated Hospital of Guangdong Pharmaceutical University from December 2022 to January 2023 were retrospectively analyzed and compared with patients who underwent surgery during the same period but were not infected with COVID-19 (a control group), to explore the impact of COVID-19 infection on lung cancer surgery. Results     We finally included 110 patients with 73 patients in the observation group (28 males and 45 females at age of 52.62±12.80 years) and 37 patients in the control group (22 males and 15 females at age of 56.84±11.14 years). The average operation time of the observation group was longer than that of the control group, and the incidence of anhelation was higher than that of the control group (P<0.05). There were no statistcal differences in blood loss, length of hospital stay, moderate or above fever rate, degree of cough and chest pain, or blood routine between the two groups. Conclusion    It is safe and feasible to perform lung cancer surgery early after recovery for COVID-19 patients with lung cancer.