TY - JOUR
T1 - Volumetric modulated arc therapy for nasopharyngeal carcinoma
T2 - A dosimetric comparison with TomoTherapy and step-and-shoot IMRT
AU - Lu, Szu Huai
AU - Cheng, Jason Chia Hsien
AU - Kuo, Sung Hsin
AU - Lee, Jason Jeun Shenn
AU - Chen, Liang Hsin
AU - Wu, Jian Kuen
AU - Chen, Yu Hsuan
AU - Chen, Wan Yu
AU - Wen, Shu Yu
AU - Chong, Fok Ching
AU - Wu, Chien Jang
AU - Wang, Chun Wei
N1 - Funding Information:
This work was supported by the National Taiwan University Hospital (grant numbers: NTUH.099-1475 , NTUH.100-1758 ).
PY - 2012/9
Y1 - 2012/9
N2 - Purpose: Volumetric modulated arc therapy (VMAT), a novel technique, employs a linear accelerator to conduct dynamic modulation rotation radiotherapy. The goal of this study was to compare VMAT with helical tomotherapy (HT) and step-and-shoot intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) patients with regard to the sparing effect on organs at risk (OARs), dosimetric quality, and efficiency of delivery. Materials and methods: Twenty patients with NPC treated by HT were re-planned by VMAT (two arcs) and IMRT (7-9 fields) for dosimetric comparison. The target area received three dose levels (70, 60, and 54 Gy) in 33 fractions using simultaneous integrated boosts technique. The Philips Pinnacle Planning System 9.0 was adopted to design VMAT, using SmartArc as the planning algorithm. For a fair comparison, the planning target volume (PTV) coverage of the 3 plans was normalized to the same level. Dosimetric comparisons between VMAT, HT, and IMRT plans were analyzed to evaluate (1) coverage, homogeneity, and conformity of PTV, (2) sparing of OARs, (3) delivery time, and (4) monitor units (MUs). Results: The VMAT, HT, and IMRT plans had similar PTV coverage with an average of 96%. There was no significant difference between VMAT and HT in homogeneity, while the homogeneity indices of VMAT (1.06) and HT (1.06) were better than IMRT plans (1.07, p < 0.05). HT plans provided a better conformity index (1.17) than VMAT (1.28, p = 0.01) and IMRT (1.36, p = 0.02). When compared with IMRT, VMAT and HT had a better sparing effect on brain stem and spinal cord (p < 0.05). The effect of parotid sparing was similar between VMAT (mean = 26.3 Gy) and HT (mean = 27.5 Gy), but better than IMRT (mean = 31.3 Gy, p < 0.01). The delivery time per fraction for VMAT (5.7 min) were much lower than for HT (9.5 min, p < 0.01) and IMRT (9.2 min, p < 0.01). Conclusions: Our results indicate that VMAT provides better sparing of normal tissue, homogeneity, and conformity than IMRT, and shorter delivery time than HT.
AB - Purpose: Volumetric modulated arc therapy (VMAT), a novel technique, employs a linear accelerator to conduct dynamic modulation rotation radiotherapy. The goal of this study was to compare VMAT with helical tomotherapy (HT) and step-and-shoot intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) patients with regard to the sparing effect on organs at risk (OARs), dosimetric quality, and efficiency of delivery. Materials and methods: Twenty patients with NPC treated by HT were re-planned by VMAT (two arcs) and IMRT (7-9 fields) for dosimetric comparison. The target area received three dose levels (70, 60, and 54 Gy) in 33 fractions using simultaneous integrated boosts technique. The Philips Pinnacle Planning System 9.0 was adopted to design VMAT, using SmartArc as the planning algorithm. For a fair comparison, the planning target volume (PTV) coverage of the 3 plans was normalized to the same level. Dosimetric comparisons between VMAT, HT, and IMRT plans were analyzed to evaluate (1) coverage, homogeneity, and conformity of PTV, (2) sparing of OARs, (3) delivery time, and (4) monitor units (MUs). Results: The VMAT, HT, and IMRT plans had similar PTV coverage with an average of 96%. There was no significant difference between VMAT and HT in homogeneity, while the homogeneity indices of VMAT (1.06) and HT (1.06) were better than IMRT plans (1.07, p < 0.05). HT plans provided a better conformity index (1.17) than VMAT (1.28, p = 0.01) and IMRT (1.36, p = 0.02). When compared with IMRT, VMAT and HT had a better sparing effect on brain stem and spinal cord (p < 0.05). The effect of parotid sparing was similar between VMAT (mean = 26.3 Gy) and HT (mean = 27.5 Gy), but better than IMRT (mean = 31.3 Gy, p < 0.01). The delivery time per fraction for VMAT (5.7 min) were much lower than for HT (9.5 min, p < 0.01) and IMRT (9.2 min, p < 0.01). Conclusions: Our results indicate that VMAT provides better sparing of normal tissue, homogeneity, and conformity than IMRT, and shorter delivery time than HT.
KW - Intensity-modulated radiation therapy
KW - Nasopharyngeal carcinoma
KW - TomoTherapy
KW - Volumetric modulated arc therapy
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U2 - 10.1016/j.radonc.2011.11.017
DO - 10.1016/j.radonc.2011.11.017
M3 - Article
C2 - 22236614
AN - SCOPUS:84867069998
SN - 0167-8140
VL - 104
SP - 324
EP - 330
JO - Radiotherapy and Oncology
JF - Radiotherapy and Oncology
IS - 3
ER -