Volumetric modulated arc therapy for nasopharyngeal carcinoma patients with poor compliance: setup error and expansion margin of target volume / 中华放射肿瘤学杂志

Objective To investigate the setup error for nasopharyngeal carcinoma (NPC) patients with poor compliance using kV cone-beam computed tomography,and to calculate the expansion margin from the clinical target volume (CTV) to planning target volume (PTV).Methods In 45 NPC patients from 2013 to 2015,the setup error,95％ confidence interval (CI)-1 for random error,and PTV-1 value were calculated.Moreover,in 16 NPC patients with poor compliance based on five verifications (random error not within 95％ CI-1),the setup error,95％ CI-2 for random error,and PTV-2 value were calculated.For the 16 special patients,PTV-1 and PTV-1 combined with PTV-2 were used to develop the plan-1 and plan-2,respectively.The dosimetric difference between plan-1 and plan-2 was evaluated.Results Both PTV-1 and PTV-2 had the largest expansion margin in the y direction.The CTV of plan-1 could not meet the requirement of the prescription dose after the setup error was introduced.Compared with plan-1,the V95％ and D95 values for the CTV of plan-2 were increased by 6.26％ and 4.43％,respectively.The D01 value was significantly larger in plan-2 than in plan-1 (P=0.005),which,however,met the clinical requirement.Conclusions In patients with poor compliance,the dose to target volume can be effectively elevated and the normal tissue can be spared from damage when PTV-1 combined with PTV-2 is selected as expansion margin.

Knock-down of miR-221 and miR-222 in the radiosensitization of breast cancer cells / 中华放射肿瘤学杂志

cells, the expression of PTEN was up-regulated while pAkt down-regulated. Conclusions AS-miR-221 and AS-miR-222 may enhance the radiosensitivity of MCF-7 breast cancer cells by up-regulating the expression of PTEN.

Movement of pulmonary lesion and diaphragm in stereotactic radiotherapy for lung cancers / 中华放射肿瘤学杂志

Objective To study the range of movement of pulmonary lesion and diaphragm in stereotactic radiotherapy for lung cancers. Methods We measured the range of movement in 48 lung cancer patients. The movement at different locations of the lung varied. The change in tumor volume from the reconstructed three dimensional (3D) images during respiration as measured by a respiratory simulator was observed. Results The movement was smaller in upper parts of lung in the X and Y directions (0.2?0.06)～(0.20?0.11 )?cm. The movement of the lower field of lung was larger than that of the upper fields (0.31?0.10)～(0.36?0.10)?cm. This is due to the heart and aortic pulsation. However, the movement was the largest in the Z direction (0.9? 0.45 )～(0.93?0.46)?cm. Moreover, if the time of computed tomography (CT) scan for each slice of lung tissue was equal to or longer than the interval of a breathing cycle, the tumor information was not lost. The reconstructed 3D images involved all the movements. The size of reconstructed 3D images changed inversely with the breathing movement. Conclusions The affection of breathing movement in lung cancer is chiefly in the Z direction. If the time of CT scan is equal to or longer than the interval of a breathing cycle, the reconstructed 3D images will encompass all the information of the tumor and its movement, showing the gross tumor volume (GTV) which does not need any safety margin. If the time of CT is shorter than the breathing cycle like the spiral CT, the reconstructed 3D image can not show the range of tumor movement.