TY - JOUR
T1 - To evaluate the accuracy of dynamic versus static IMRT delivery using portal dosimetry
AU - Clemente, S.
AU - Caivano, R.
AU - Cozzolino, M.
AU - Califano, G.
AU - Chiumento, C.
AU - Fiorentino, A.
AU - Fusco, V.
PY - 2014/2
Y1 - 2014/2
N2 - Introduction: To evaluate the delivery accuracy of dynamic (DMLC) and static (SMLC) intensity modulated radiation therapy (IMRT) techniques using portal dosimetry (PD) in Varian Eclipse Treatment Planning System. Materials and methods: Seven DMLC IMRT Head and Neck plans were retrospectively generated for the study using SMLC mode at 20, 10 and 5 levels of intensity (SMLC20, SMLC10, SMLC5). Dosimetric verifications performed by PD on a total of 107 fields were evaluated using the gamma index (maximum γ max, average γ avg, percentage of points with γ % ≤ 1). The images were acquired at a source-detector distance of 100 cm at gantry zero degree and also at clinically planned gantry angles. Results: For both modes, measurements are within acceptable criteria. γ % ≤ 1 improves by increasing SMLC levels (+3.4 % from SMLC5 to SMLC20, p <0.001) and using DMLC (+3.9 % and +0.6 % compared to SMLC5 and SMLC20, respectively, p <0.001). Also γ max parameter improves significantly by increasing SMLC levels (+22 % from SMLC5 to SMLC20) and using DMLC (+34 % and +16 % compared to SMLC5 and SMLC20, respectively). The effect of the gantry rotation influences the delivery accuracy by up to -7 % (p <0.05). The effect of leaves travelling direction was almost negligible (1 %). Conclusions: A good agreement between calculated and measured fluences was obtained for DMLC and SMLC techniques at higher intensity levels; however, DMLC delivery ensures the best reproduction of computed fluence maps. The gantry rotation influences the delivery accuracy in particular for SMLC modes at lower intensity levels.
AB - Introduction: To evaluate the delivery accuracy of dynamic (DMLC) and static (SMLC) intensity modulated radiation therapy (IMRT) techniques using portal dosimetry (PD) in Varian Eclipse Treatment Planning System. Materials and methods: Seven DMLC IMRT Head and Neck plans were retrospectively generated for the study using SMLC mode at 20, 10 and 5 levels of intensity (SMLC20, SMLC10, SMLC5). Dosimetric verifications performed by PD on a total of 107 fields were evaluated using the gamma index (maximum γ max, average γ avg, percentage of points with γ % ≤ 1). The images were acquired at a source-detector distance of 100 cm at gantry zero degree and also at clinically planned gantry angles. Results: For both modes, measurements are within acceptable criteria. γ % ≤ 1 improves by increasing SMLC levels (+3.4 % from SMLC5 to SMLC20, p <0.001) and using DMLC (+3.9 % and +0.6 % compared to SMLC5 and SMLC20, respectively, p <0.001). Also γ max parameter improves significantly by increasing SMLC levels (+22 % from SMLC5 to SMLC20) and using DMLC (+34 % and +16 % compared to SMLC5 and SMLC20, respectively). The effect of the gantry rotation influences the delivery accuracy by up to -7 % (p <0.05). The effect of leaves travelling direction was almost negligible (1 %). Conclusions: A good agreement between calculated and measured fluences was obtained for DMLC and SMLC techniques at higher intensity levels; however, DMLC delivery ensures the best reproduction of computed fluence maps. The gantry rotation influences the delivery accuracy in particular for SMLC modes at lower intensity levels.
KW - Delivery accuracy
KW - DMLC
KW - Portal dosimetry (PD)
KW - SMLC
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U2 - 10.1007/s12094-013-1065-6
DO - 10.1007/s12094-013-1065-6
M3 - Article
C2 - 23793811
AN - SCOPUS:84893798541
VL - 16
SP - 208
EP - 212
JO - Clinical and Translational Oncology
JF - Clinical and Translational Oncology
SN - 1699-048X
IS - 2
ER -