Author/Authors :
Shao, Y Institute of Modern Physics - Fudan University, Shanghai, China - Department of Radiation Oncology - Shanghai Chest Hospital - Shanghai Jiao Tong University, Shanghai, China , Chen, H Institute of Modern Physics - Fudan University, Shanghai, China - Department of Radiation Oncology - Shanghai Chest Hospital - Shanghai Jiao Tong University, Shanghai, China , Wang, H Institute of Modern Physics - Fudan University, Shanghai, China - Department of Radiation Oncology - Shanghai Chest Hospital - Shanghai Jiao Tong University, Shanghai, China , Cheng, Y Department of Radiation Oncology - Shanghai Chest Hospital - Shanghai Jiao Tong University, Shanghai, China , Zhu, Z Department of Radiation Oncology - Shanghai Chest Hospital - Shanghai Jiao Tong University, Shanghai, China , Zhuo, W Institute of Radiation Medicine - Fudan University - Shanghai, China , Kong, Q Institute of Modern Physics - Fudan University, Shanghai, China , Xu, Z Department of Radiation Oncology - Shanghai Chest Hospital - Shanghai Jiao Tong University, Shanghai, China
Abstract :
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° 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. γ analysis was carried out with criteria of 2% / 2 mm. The passing
rate shall over than 90%. If the passing rate of γ analysis was lower than 90%,
two-isocenter plan was created and carried out γ analysis as well. Results: According
to the γ analysis, when the distance from lesions to the single-isocenter was more
than 6cm, both in the horizontal or 45° direction, the passing rate was lower than 90%.
Based on γ analysis, two-isocenter plans were created. After verification, the passing
rate was higher than 90%. Conclusions: The maximum distance of using singleisocenter
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.
Keywords :
Multiple lung lesions , single-isocenter , SBRT , dose accuracy
