Ex) Article Title, Author, Keywords
Ex) Article Title, Author, Keywords
Korean Journal of Medical Physics 2016; 27(3): 111-116
Published online September 30, 2016
Copyright © Korean Society of Medical Physics.
Kyung Hwan Chang, Yunseo Ji, Jungwon Kwak, Sung Woo Kim, Chiyoung Jeong, Byungchul Cho, Jin-hong Park, Sang Min Yoon, Seung Do Ahn, Sang-wook Lee
This study is to evaluate the dosimetric impact of dosimetric leaf gap (DLG) and transmission factor (TF) at different measurement depths and field sizes for high definition multileaf collimator (HD MLC). Consequently, its clinical implication on dose calculation of treatment planning system was also investigated for pancreas stereotactic body radiation therapy (SBRT). The TF and DLG were measured at various depths (5, 8, 10, 12, and 15 cm) and field sizes (6×6, 8×8, and 10×10 cm2) for various energies (6 MV, 6 MV FFF, 10 MV, 10 MV flattening filter free [FFF], and 15 MV). Fifteen pancreatic SBRT cases were enrolled in the study. For each case, the dose distribution was recomputed using a reconfigured beam model of which TF and DLG was the closest to the patient geometry, and then compared to the original plan using the results of dose-volume histograms (DVH). For 10 MV FFF photon beam, its maximum difference between 2 cm and 15 cm was within 0.9% and it is increased by 0.05% from 6×6 cm2 to 10×10 cm2 for depth of 15 cm. For 10 MV FFF photon beam, the difference in DLG between the depth of 5 cm and 15 cm is within 0.005 cm for all field sizes and its maximum difference between field size of 6×6 cm2 and 10×10 cm2 is 0.0025 cm at depth of 8 cm. TF and DLG values were dependent on the depth and field size. However, the dosimetric difference between the original and recomputed doses were found to be within an acceptable range (<0.5%). In conclusion, current beam modeling using single TF and DLG values is enough for accurate dose calculation.
KeywordsHDMLC, Dosimetric leaf gap (DLG), MLC transmission factor, Stereotactic body radiation therapy (SBRT), Pancreas
pISSN 2508-4445
eISSN 2508-4453
Formerly ISSN 1226-5829
Frequency: Quarterly