other Radiobiology Radiobiology یادداشت فنی Technical Note <div style="text-align: justify;">Background: To investigate the maximum distance from lesions to the single-isocenter that can ensure the accuracy of dose delivery for single-isocenter/two-lesions intensity modulated radiotherapy (IMRT) lung stereotactic body radiation therapy (SBRT). Materials and Methods: We employed a lung phantom made of acrylic material. Sixteen gross tumor volumes (GTVs) of the same shape and size were delineated on the CT images. The single-isocenter was placed on the center of the first GTV (GTV1). Six GTV centers were located at left and were 2-7 cm away from the single-isocenter. Nine GTV centers were in the 45&deg; direction and were 2-10 cm away from the single-isocenter. Plans were created for the first planning target volume (PTV1) and other fifteen PTVs separately with the same isocenter. Compass was used to verify the treatment plans. &gamma; analysis was carried out with criteria of 2% / 2 mm. The passing rate shall over than 90%. If the passing rate of &gamma; analysis was lower than 90%, two-isocenter plan was created and carried out &gamma; analysis as well. Results: According to the &gamma; analysis, when the distance from lesions to the single-isocenter was more than 6cm, both in the horizontal or 45&deg; direction, the passing rate was lower than 90%. Based on &gamma; analysis, two-isocenter plans were created. After verification, the passing rate was higher than 90%. Conclusions: The maximum distance of using single-isocenter to treat multiple lung lesions is 5 cm. The result provides a reference for our center and other centers when using this technique to treat multiple lung lesions.</div> Multiple lung lesions, single-isocenter, SBRT, dose accuracy. 241 244 http://ijrr.com/browse.php?a_code=A-10-2188-89&slc_lang=other&sid=1 Y. Shao 7900319475328460020947 7900319475328460020947 No Institute of Modern Physics, Fudan University, Shanghai, 200433 China H. Chen 7900319475328460020948 7900319475328460020948 No Institute of Modern Physics, Fudan University, Shanghai, 200433 China H. Wang 7900319475328460020949 7900319475328460020949 No Institute of Modern Physics, Fudan University, Shanghai, 200433 China Y. Cheng 7900319475328460020950 7900319475328460020950 No Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 20030, China Z. Zhu 7900319475328460020951 7900319475328460020951 No Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 20030, China W. Zhuo 7900319475328460020952 7900319475328460020952 No Institute of Radiation Medicine, Fudan University, Shanghai, 20032, China Q. Kong 7900319475328460020953 7900319475328460020953 No Institute of Modern Physics, Fudan University, Shanghai, 200433 China Z. Xu xzyong12vip@sina.com 7900319475328460020954 7900319475328460020954 Yes Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 20030, China