AIM:To compare the volumetric-modulated arc therapy AT plans ith conventional sliding indo intensity-modulated radiotherapy c-I RT plans in esophageal cancer EC . METHODS:Tenty patients ith EC ere selected, including ...AIM:To compare the volumetric-modulated arc therapy AT plans ith conventional sliding indo intensity-modulated radiotherapy c-I RT plans in esophageal cancer EC . METHODS:Tenty patients ith EC ere selected, including 5 cases located in the cervical, the upper, the middle and the lo er thorax, respectively. Five plans ere generated ith the eclipse planning system:three using c-IMRT with 5 fields (5F), 7 fields (7F) and 9 fields (9F), and two using VMAT with a single arc 1A and double arcs 2A . The treatment plans ere designed to deliver a dose of 60 Gy to the plan-ning target volume Tith the same constrains in a 2.0 Gy daily fraction, 5 d a eek. lans ere normalized to 95% of the T that received 100% of the prescribed dose. We examined the dose-volume histogram parameters of T and the organs at risk OAR such as lungs, spinal cord and heart. onitor units U and normal tissue complication probability NTC of OAR ere also reported. RESULTS:Both c-I RT and AT plans resulted in abundant dose coverage of T for EC of different locations. The dose conformity to T as improved as the number of field in c-IMRT or rotating arc in VMAT as increased. The doses to T and OAR in AT plans ere not statistically different in comparison ith c-I RT plans, ith the follo ing exceptions:in cervical and upper thoracic EC, the conformity index CI as higher in VMAT (1A 0.78 and 2A 0.8) than in c-IMRT (5F 0.62, 7F 0.66 and 9F 0.73) and homogeneity was slightly better in c-IMRT (7F 1.09 and 9F 1.07) than in VMAT (1A 1.1 and 2A 1.09). Lung V30 was lower in VMAT (1A 12.52 and 2A 12.29) than in c-IMRT (7F 14.35 and 9F 14.81). The humeral head doses were significantly increased in AT as against c-I RT. In the middle and lower thoracic EC, CI in VMAT (1A 0.76 and 2A 0.74) was higher than in c-IMRT (5F 0.63 Gy and 7F 0.67 Gy), and homogeneity was almost similar bet een AT and c-I RT. 20 2A 21.49 Gy vs 7F 24.59 Gy and 9F 24.16 Gy) and V30 (2A 9.73 Gy vs 5F 12.61 Gy, 7F 11.5 Gy and 9F 11.37 Gy) of lungs in AT ere lo er than in c-I RT, but lo doses to lungs (V5 and V10) were increased. V30 (1A 48.12 Gy vs 5F 59.2 Gy, 7F 58.59 Gy and 9F 57.2 Gy), V40 and 50 of heart in AT as lo er than in c-I RT. Us in AT plans ere significantly reduced in comparison ith c-I RT, maximum doses to the spinal cord and mean doses of lungs ere similar bet een the t o techniques. NTC of spinal cord as 0 for all cases. NTC of lungs and heart in AT ere lo er than inc-I RT. The advantage of AT plan as enhanced by doubling the arc. CONCLUSION:Compared ith c-I RT, AT, especially the 2A, slightly improves the OAR dose sparing, such as lungs and heart, and reduces NTC and U ith a better T coverage.展开更多
基金Supported by The National Natural Science Foundation of China, No. 30870738
文摘AIM:To compare the volumetric-modulated arc therapy AT plans ith conventional sliding indo intensity-modulated radiotherapy c-I RT plans in esophageal cancer EC . METHODS:Tenty patients ith EC ere selected, including 5 cases located in the cervical, the upper, the middle and the lo er thorax, respectively. Five plans ere generated ith the eclipse planning system:three using c-IMRT with 5 fields (5F), 7 fields (7F) and 9 fields (9F), and two using VMAT with a single arc 1A and double arcs 2A . The treatment plans ere designed to deliver a dose of 60 Gy to the plan-ning target volume Tith the same constrains in a 2.0 Gy daily fraction, 5 d a eek. lans ere normalized to 95% of the T that received 100% of the prescribed dose. We examined the dose-volume histogram parameters of T and the organs at risk OAR such as lungs, spinal cord and heart. onitor units U and normal tissue complication probability NTC of OAR ere also reported. RESULTS:Both c-I RT and AT plans resulted in abundant dose coverage of T for EC of different locations. The dose conformity to T as improved as the number of field in c-IMRT or rotating arc in VMAT as increased. The doses to T and OAR in AT plans ere not statistically different in comparison ith c-I RT plans, ith the follo ing exceptions:in cervical and upper thoracic EC, the conformity index CI as higher in VMAT (1A 0.78 and 2A 0.8) than in c-IMRT (5F 0.62, 7F 0.66 and 9F 0.73) and homogeneity was slightly better in c-IMRT (7F 1.09 and 9F 1.07) than in VMAT (1A 1.1 and 2A 1.09). Lung V30 was lower in VMAT (1A 12.52 and 2A 12.29) than in c-IMRT (7F 14.35 and 9F 14.81). The humeral head doses were significantly increased in AT as against c-I RT. In the middle and lower thoracic EC, CI in VMAT (1A 0.76 and 2A 0.74) was higher than in c-IMRT (5F 0.63 Gy and 7F 0.67 Gy), and homogeneity was almost similar bet een AT and c-I RT. 20 2A 21.49 Gy vs 7F 24.59 Gy and 9F 24.16 Gy) and V30 (2A 9.73 Gy vs 5F 12.61 Gy, 7F 11.5 Gy and 9F 11.37 Gy) of lungs in AT ere lo er than in c-I RT, but lo doses to lungs (V5 and V10) were increased. V30 (1A 48.12 Gy vs 5F 59.2 Gy, 7F 58.59 Gy and 9F 57.2 Gy), V40 and 50 of heart in AT as lo er than in c-I RT. Us in AT plans ere significantly reduced in comparison ith c-I RT, maximum doses to the spinal cord and mean doses of lungs ere similar bet een the t o techniques. NTC of spinal cord as 0 for all cases. NTC of lungs and heart in AT ere lo er than inc-I RT. The advantage of AT plan as enhanced by doubling the arc. CONCLUSION:Compared ith c-I RT, AT, especially the 2A, slightly improves the OAR dose sparing, such as lungs and heart, and reduces NTC and U ith a better T coverage.
